Blog - The Eating Academy | Peter Attia, M.D.

Is a low fat diet best for weight loss?

Is a low fat diet best for weight loss?
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I know many of you are awaiting Part II of the mini-series on ketosis, but I’d like to digress briefly to comment on a study published last week, which a number of you have asked about.

In this study, by Hooper et al., titled Effect of reducing total fat intake on bodyweight: systematic review and meta-analysis of randomised controlled trials and cohort studies, the authors take aim at addressing one of the most important questions underpinning our current epidemic of obesity and, by extension, its related diseases: Is there a preferred dietary intervention that can lead to a long term reduction in body fat?

To address this important question the authors conducted an exhaustive meta-analysis of 33 randomized controlled trials (RCTs) and 10 cohort studies in which patients were treated with a low-fat diet for outcomes beyond weight reduction. For example, they examined studies which treated women at risk for breast cancer (e.g., due to abnormal mammography) with a low-fat diet to test if the diet reduced their likelihood of progressing to breast cancer.  Or studies where subjects at risk for heart disease (e.g., due to biomarkers or a strong family history) were randomized to a low-fat diet versus a standard diet to examine the impact on biomarkers for heart disease.

Before getting into the details of this analysis I’d like to reiterate a point I made in a previous post. James Yang, one of my mentors when I was in medical school and again in fellowship, always reiterated, “a hundred sow’s ears makes not a pearl necklace” when talking about meta-analyses.  Stated another way, Dr. Samuel Shapiro, a distinguished professor in Cape Town, South Africa, made this comment on meta-analyses:

“As a matter of logic, it is fallacious to argue that a series of inadequate studies taken together cancel out their inadequacies.”

In other words, a meta-analysis, no matter how large, no matter how elaborate in statistical tools, no matter how erudite in authorship, can be no better than the sum of its parts. To quote a good friend of mine, James Lambright, the former Chief Investment Officer of the TARP program, a meta-analysis “is somewhat analogous to ratings agencies looking at a huge pile of mortgages and concluding that collectively they deserve an ‘A’ rating, without noticing that the underlying mortgages might all be lousy.”  Nice.  A meta-analysis is basically a CDO. Some good…many not.

A close analysis of the 33 randomized controlled studies included in this systematic review reveals a common trend in most, though not all, of them. (I’ve not looked at the 10 cohort studies for the obvious reason – we will never glean cause and effect from such studies.)

The studies, almost without exception, followed a pretty typical pattern.  The subjects were divided into two (sometimes more) groups and randomized into a treatment arm (or arms) and a control arm.  Here is a typical example of how the investigators interact with the subjects in the treatment and control arms:

Treatment arm: Patients received individualized and/or group counseling to reduce fat intake and increase consumption of fruits and vegetables on a weekly and then monthly basis, often with cooking classes, behavioral interventions, and newsletters. In some trials, the counseling intervention for the low-fat diet arm included weekly or monthly calls from a study dietitian to troubleshoot dietary challenges.

Control arm: Patients received no, or very little, dietary counseling or interventions. Controls were simply instructed to consume their standard diet for the duration of the study.

To my counting, about 99.2% of the nearly 74,000 subjects (all but about 600 subjects) across the 33 RCTs examined were subjected to this treatment bias, referred to more specifically as performance bias. (Yes, this required actually reading — very quickly — each of the studies used in this analysis.)

According to the Cochrane methodology, the gold standard for research methodology, “performance bias refers to systematic differences between groups in the care that is provided, or in exposure to factors other than the interventions of interest. Randomisation of subjects and even blinding the investigators does not eliminate this (performance) bias.”

(I include this last comment about blinding because the BMJ study authors list the absence of blinding as a potential weakness of their study, though they don’t mention performance bias.)

In other words, it is not clear if the pooled effects observed in this meta-analysis reflect the low-fat dietary intervention, the counseling effect, or some combination of both.

Let me illustrate with an example.  Assume you’re one of the subjects in the treatment group.  Upon enrollment in the study, you undergo a lengthy assessment with a study dietician, where you provide a 5-day log of everything you’ve been eating for evaluation.  You are given hours of counseling on how to avoid dietary fat.  You are provided with menus and recipes to cook low-fat (and presumably healthy) dishes. Every few weeks you meet alone (or in group with other subjects in the low-fat arm) to receive additional support and counseling.  Every month a study dietitian calls you to answer any questions you might have and to provide encouragement.

Does anyone think this intervention, regardless of what you’re being prescribed to eat, does not make a difference? If the guidance of the Cochrane group isn’t enough, I can absolutely attest to this from my experience working with people.  We all benefit from encouragement, and the encouragement we get has an effect beyond the dietary composition.

This suggests a slightly different conclusion than that proposed by Hooper et al. Rather than concluding that lower total fat intake leads to small but statistically significant and clinically meaningful, sustained reductions in body weight in adults, it seems a more accurate conclusion would be that lower total fat intake, coupled to an intensive counseling and support regimen, leads to small but statistically significant and clinically meaningful, sustained reductions in body weight in adults compared to a standard diet without counseling and support.

Because the counseling effect could have other unintended effects, (for example, consumption of less sugar, fewer highly refined or processed foods, or more exercise), we can’t be sure what caused the measured effect.

The best studies in this space normalize for intervention effect across all treatment arms.  This way the investigators have some way of assessing the impact of the actual intervention in question – the diet.

A couple of other oddities about this study

If you really wanted to understand the impact of a low-fat diet on weight loss (or some better marker of actual fat loss), it seems that actually looking at trials where this was being tested might be a better place to look. There is no shortage of such trials out there, including the work of Gardner, Foster, Ludwig, Dashti, Shai, and others.  The advantage of looking at diet studies include:

  1. They usually remove the performance bias I described above.  Typically (though not always) in these studies all subjects are given the same support and dietary counseling.
  2. Such studies are statistically powered to detect meaningful differences in the outcome or endpoint of interest – fat loss (or some proxy of it).

I’ve written before about the difference between statistical significance and statistical power, so I won’t repeat the explanation.  But, I’d like to point out the problem of looking at endpoints that were not powered.  The largest study included in this BMJ meta-analysis was the Women’s Heath Initiative (WHI), a study of nearly 50,000 post-menopausal women.  The WHI, which I talked about at length in the presentation in this post, tested a low-fat dietary intervention over an average follow-up of nearly 6 years. The study was powered to detect hard outcomes like cancer incidence, heart attacks, and death.  That’s why the study was so large.  But when a study is this large, it’s actually quite easy to find statistical significance in any number of parameters, even if they are not clinically significant or relevant.  Look at Table 3 from the JAMA report of the WHI:

JAMA table 3

You’ll notice that in waist circumference, for example, some of the subsets showed a statistically significant difference.  Overall (bottom right section of table) the control (normal fat) group increased their waist circumference over the study from 89 cm to 90.4 cm, while the low-fat intervention group increased from 89 to 90.1 cm, a difference of 3 mm, which achieved a p-value of 0.04.   While this is statistically significant (and therefore included in the BMJ paper as a study for consideration), it’s not really clinically significant.  In fact, it’s not clear if any of the statistical differences in the WHI are clinically significant.  Waist-to-hip measurements didn’t change, which of all the anthropometric changes is probably the most relevant to consider (absent actual body composition data).

Interesting side-note: both the treatment and intervention group lost a bit of weight, yet both groups saw an increase in BMI, suggesting they got shorter over the duration of the study. Furthermore, despite scrutinizing this table and the paper for longer than I care to admit, I cannot for the life of me explain the arithmetic. The authors logically define “change” as the difference between follow-up and baseline.  However, examination of this table reveals the arithmetic to be incorrect more often than it is correct.  Some instances may be attributable to rounding errors and significant figures, but many are not. It is possible drop-out accounts for this, I suppose.

My micro point

Notwithstanding the fact that the WHI suffered from performance bias:

“Women assigned to the control group received a copy of the Dietary Guidelines for Americans as well as other diet- and health-related educational materials, but otherwise had no contact with study dietitians. In contrast, women randomized to dietary intervention were assigned to groups of 8 to 15 participants for a series of sessions structured to promote dietary and behavioral changes that would result in reducing total dietary fat to 20% and increasing intake of vegetables and fruit to 5 or more servings and grains (whole grains encouraged) to 6 or more servings daily.”

The differences observed, despite this bias, were statistically significant because of the sample size, but were not clinically significant.

My macro point

A meta-analysis based on studies like this is not the best way to answer the question at hand.  Sadly, I suspect, most providers (e.g., physicians, dietitians, nutritionists) may not appreciate this given how the media reports on this kind of publication.

 

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About the Author:

Peter Attia, M.D., is the co-founder and President of the Nutrition Science Initiative (NuSI), a non-profit based in San Diego, CA. He received his B.Sc. from Queen's University in Canada and his M.D. from Stanford Medical School in California. After his surgical residency in general surgery at Johns Hopkins he worked as a consultant at McKinsey & Company. He founded NuSI with scientific journalist Gary Taubes in 2012.

Discussion

  1. Joy  December 18, 2012

    For many years I frequented a weight loss centre. The goal was ketosis and I always lost weight.
    I would receive injections of vit B6 and B12. It seemed to help with energy.
    Now I am following the diet at home, it is a very, low calorie diet. Low in calories, fat and carbs.

    Do you have any thoughts onthe injectable vitamins and their role in ketosis?

    Thank you
    Joy

    (reply)
    • Peter Attia  December 18, 2012

      Not sure how much of a role the injections play, if any. May be true, true, and unrelated, as the saying goes.

  2. Sarah  December 18, 2012

    Hi Peter,

    Just wanted to say i really enjoy your blog. I have been in nutritional Ketosis for about 8 week, prior to that i was following low carb paleo. However making the common mistakes of too much protein and too little fat. i am testing my blood ketones daily and must say i have great energy and no hunger. I actually have to remind myself to eat.

    I am still finding my performance when exercising is not as good as it use to be, however i figure this will just take time. i have started taking bone broth, which has been great from my low blood pressure and light headedness.

    Keep up the great work. Would be great if you came to Australia for a presentation!

    (reply)
    • Peter Attia  December 18, 2012

      Thank you, Sarah. I haven’t been to Australia since 2009, but it sure was amazing. I actually got to see Pearl Jam in concert twice in one trip! Once in Sydney and once in Perth. The best part, despite being there for over 2 weeks, and doing business in 6 cities, I got to swim in a 50 meter pool every single day I was there…You know they’re doing something right in a country when that’s the case.

  3. George @ the High Fat Hep C Diet  December 18, 2012

    Sadly, this was reported in the NZ papers as “low fat diets effective for weight loss” and I’m sure was seen by many as a counterblast to recent Taubesist-Lustigist propaganda successes in these parts.

    (reply)
  4. Stipetic  December 18, 2012

    “As a matter of logic, it is fallacious to argue that a series of inadequate studies taken together cancel out their inadequacies.”

    Or in truck driver speak, “Garbage in, garbage out.” Another study for the nutritional study dump site, which, over the last 50 years, has been filling up rather rapidly. And, oh, the stench!

    Thanks for doing the legwork. Now, if we could direct a few journalists your way.

    (reply)
    • Peter Attia  December 18, 2012

      Yes, that’s certainly a more direct way to say it.

  5. FrankG  December 18, 2012

    I’m not sure if there is a more pressing need for better studies, or better interpretation of the existing ones!

    The biggest lesson for me reading GC,BC was that I no longer blindly accept the word of “experts” no matter what authority they claim. I want to see evidence that will stand up to scrutiny.

    BTW I am no completely clear if the mixed metaphor was intentional or not? I’ve heard of “casting pearls befroe swine” (a biblical reference) and “making a silk purse out of a sow’s ear” :-)

    (reply)
    • Peter Attia  December 18, 2012

      It’s just what I used to call a “pure Yang-ism” … classic, and it sure made the point (at least to me!)

  6. lockard  December 18, 2012

    great points here- it should cause us to stop and wonder how much “sound” science is out there. But at that rate there are always so many variables at what point is is possible to truly test a theory? You can’t lock 2 big enough groups up and then only change one thing (like fat content) and keep them looked up long enough to see real data. Most of these studies only use people who still have to make their own choices and then self report, which could let to people cheating and not telling. Who could you get “real” data?

    (reply)
  7. Richard Shaffner  December 18, 2012

    Peter,

    Thank you for clarifying this and other studies, for all of us. I have enjoyed your blog posts and videos immensely. With your story as added motivation, I’m losing weight, getting in better shape, and feeling great!

    In your videos and blogs, you’ve pointed out that protein creates less of an insulin response than carbs, but that it can depend on what else is eaten, what kind of protein it is, and how much it is. I’ve seen studies on Pubmed that seem to provide conflicting results (that protein alone, and protein with carbs, can cause a significant increases in blood glucose and the insulin response).

    I suspect you could write a long answer to clarify this issue for us. That would be nice, of course, but I know you’re busy and have many priorities. Can you give us a summary version, about the insulin response from eating protein and the effect that may have on weight loss for those of us who are still insulin-resistant?

    Thanks!

    Richard

    (reply)
    • Peter Attia  December 18, 2012

      You’re right, Richard. The quality and preparation of the protein plays a huge role. For example, hydrolyzed whey protein probably kicks up more of an insulin fuss than, say, a bowl of rice. But the story is much more nuanced than just the insulin response. It’s more about what that insulin response drives (e.g., protein synthesis vs. impedance of lipolysis).

  8. Alla Danilkovitch  December 18, 2012

    Dear Peter and other participants of this blog,
    Desperately need your advice. I am a long distance runner, mostly marathons. I believe that I am very “carb tolerant” (49 yo,16.6% body fat, 5’6”, ~125 Lb, now running ~3:30 marathons, best 3:13), but my scientific nature pushed me to try low carb diet. The main goal is to see how switching to fat as a fuel will affect my sport performance. I am at week 5. Main problem: cannot tolerate running paces that were easy for me on carbs.
    My ketones are dramatically dropping after workouts, and glucose is going up. Also, I have another observation that my resting heart rate is high: it was 45-48 on carbs, and now it is 55-58!
    My theory is that I have fast increase in catecholamines to any stress inducers including running. This leads to fast release of glucose from liver (HGO), and then insulin is up and my fat oxydation is completely blocked. So, I cannot utilize fat and don’t have enough carbs to support my running. Also, catechoamines are known to incsease perceived exertion. I have the same response to other exercises, but I can tolerate better.
    For example, yeasterday I did hot yoga (Bikram, 90 min, 105 F). Ketone before -1.3; after -0.2!
    In general, my ketones are at the low end of ketosis, especially in the morning. I eat 85% fat, 30-40 g carbs, very moderate protein. Sodium intake is good. I do have a lot of positive effects: fast recovery post-workouts, not hungry, sustain level of energy, good mental concentration. I don’t want to give up, and I am not sure that I just need to wait longer and everything will be fine. Trying to be proactive. I need to start training for Boston marathon, but right now I cannot handle my training paces. Tomorrow I will have my annual medical exam. Any advices for lab tests? Thx a lot. Hope that together we will be able to solve this problem. I am sure that other people may experience the same.

    (reply)
    • Joshua  December 18, 2012

      I had similar issues when switching over to a ketogenic diet, especially on my longer road rides (30+ miles). Personally, I try not to eat any carbs going into the workout (I do carbs PWO), just electrolytes and a cup of coffee for a little caffeine. This seems to prime my body for metabolizing ketones the best, and during the ride I drink a mixture of water, electrolytes and Superstarch, which seems to keep my body mostly in ketosis while also adequately supplying glucose to my muscles. Since adding the Superstarch I have seen significant improvements, you should give it a try and see what you think. Good Luck!

    • Bobby  December 18, 2012

      Peter: I found Alla’s question quite interesting since I have experienced similar issues. I wonder if you can shed any light on what we are doing wrong or missing. Or does Ketosis not work for many of us?

    • Peter Attia  December 19, 2012

      Very difficult to address in a quick response. I have no idea what’s going on, but I would need a lot of data to sort out a few hypotheses. Hopefully subsequent post on ketosis may shed some light.

    • Hemming  December 19, 2012

      FWIW, I’ve had sort of the same response after 5 weeks. It has taken me more like 10 weeks to feel really good on a ketogenic diet. I can only say that I’m now feel the improvements in endurance and strength almost daily. I think you should keep it, make sure to get adequate protein – not too much not too little. Give it some more weeks and I think you’ll be able to perform at the same level again.

    • Diana Attuso  February 5, 2013

      Alla,
      I’m wondering if you have read “The Art and Science of Low Carbohydrate Performance”? http://www.amazon.com/The-Art-Science-Carbohydrate-Performance/dp/0983490716/
      I believe this book was written to specifically address your concerns…

      Good luck!

    • Ray  June 25, 2014

      A lot to swallow there…….I’d say at 5 weeks, it is too early to determine your maximum benefit of becoming a true fat burner. All other data does not really matter much. This is a big change for the body. Keep on doing what you are doing…get the super starch for 2+hr runs. Keep documenting.

  9. Troy Wynn  December 18, 2012

    These are smart people organizing this type of analysis. They too know what you know about the flaws, yet this rubbish get’s published, and promoted in the media “as low fat is a good thing for your health.” Why???

    (reply)
    • Joshua  December 18, 2012

      The media are lagging indicators, not leading. The conventional wisdom is “lowfat = good”, and until that conventional wisdom is upset by thought leaders, the media will keep spouting it.

      As for the people doing these meta-analyses, it’s all about the funding. For whatever reason, low-fat studies are still getting more funding than high-fat studies.

    • Peter Attia  December 18, 2012

      Have you read “Mistakes Were Made (But not by me)” by Carol Tavris?

    • Diana Attuso  February 5, 2013

      You ever heard of “confirmation bias”?

  10. Birgit  December 18, 2012

    Peter,
    I also see the difficulty of doing a tightly controlled study. Speaking as a non-scientist I’m curious how useful it would be to do a “meta-analysis” of many n=1 experiments as the one that you do and that Jimmy Moore and many others are currently doing. If there were a place (possibly online) to collect success stories/blogs in a summary version that are done by fairly meticulous people like yourself I suspect that the total evidence would be very significant, even though not true “science”.
    I am thinking of the possibility of including evidence in as diverse areas as ketogenic diets for weight loss, cancer treatment, epilepsy treatment, heart disease etc.

    Birgit

    (reply)
    • Peter Attia  December 18, 2012

      As you know, I’m a huge believer in “n of 1″ stuff, but I’m not sure it’s a reliable way to do science.

    • KevinF  December 18, 2012

      Among the pitfalls here, there would clearly be a massive selection bias that would undermine any meta analysis. You’d only be sampling a certain type of person: a super-motivated person who adopted a low carb diet, who was HAPPY enough with it to stick with it, is motivated enough to get special tests and report them online, who probably is or was overweight (hence adoption of the diet), who very likely has reason to be concerned with heart disease and diabetes (hence discovering this world in the first place). In short you’d be sampling a bunch of fat, carb-sensitive, insulin resistant but motivated and compliant people who read blogs (like me!).

    • Birgit  December 19, 2012

      Ha,ha, great explanation Kevin, that makes sense, and of course you are right. So I guess all of us who are doing these self-experiments will have to just continue doing them and sharing the results so that more people will give it a try. :)

  11. Joshua  December 18, 2012

    The first thing that jumped out at me was this sentence “For example, they examined studies which treated women at risk for breast cancer “.

    I have to think that if you take one group of at-risk people and tell them that they can affect their outcome by changing their lifestyle, they are going to have better outcomes that the group that is told “good luck!”

    Hmmm. I think I just regurgitated what you already said. Ahh well.

    (reply)
  12. Thanesh Rajandran  December 18, 2012

    Peter,

    One of the main reasons I read your blog is the valuable insight you drop on developing one’s critical thinking (the other reason is how you discuss things starting with first principles, just like how Feynman would think). This post is an excellent demonstration of that. Unfortunately, to enumerate on such matter leads to lengthiness of your post, which turns off many people, an issue I sadly see no way around.

    On another note, I would like to share with you an article that perhaps brilliantly illustrate another common trap buried in many scientific papers:
    http://www.americanscientist.org/issues/id.15964,y.2013,no.1,content.true,page.1,css.print/issue.aspx

    (reply)
    • Peter Attia  December 18, 2012

      Thanesh, this is a fantastic article. Thanks very much for sharing. Completely agree!

  13. Jim Cote  December 18, 2012

    Peter,

    Someone recently showed this article to me so I can now forward something intelligent back. I’m amazed at people sending me articles to explain how I’m dieting incorrectly. I started on a ketogenic diet back in April and have gone from a 42″ waist to a 34″ waist.

    Your work has been a tremendous help and has provided much appreciated encouragement. As it is the season, do you have a list of preferred charities for donations in your honor?

    Thank you.

    (reply)
    • Peter Attia  December 18, 2012

      Sadly, Jim, I’m pretty sure not one person who sent you this actually read the paper, let alone one of the papers that went into the meta-analysis.

    • Edward  December 19, 2012

      Donate to NuSI. It is the single best thing you can do to promote real research by real scientists.

  14. Exceptionally Brash  December 18, 2012

    Very interesting hearing your take on this study. My ears perked up when I heard that this study included no studies that tried to study weight loss. It reminded me of that great streetlight joke, “Why are you searching for your wallet here, sir?”

    It would have been more interesting and even out some of the performance bias if they had also included several of the many wonderful studies with do-nothing SAD as the control and a high-fat diet studied as a way to reduce all ills. (OK, this is sort of another sad joke.)

    Now as for your photos, clearly the high-fat pig parts came before the fat-free pearls, a good move indeed!

    And speaking of performance bias, what would you call that bias that all LC’ers have to face when they are constantly taunted by well-meaning friends and medical professionals. For the LC diet to be successful, there has to be a very high level of “activation energy” input to counteract all that talk of “dangerous fad diets” while the low-fat folks get their brownie points issued immediately. Does overt hostility to one’s diet choices supply some hormetic effect to weight loss?

    (reply)
    • Peter Attia  December 20, 2012

      Hmmm. Not sure that represents a formal “bias” in the technical sense, but you’re absolutely correct this is an issue.

  15. CU  December 18, 2012

    According to the study “Meta-analysis of data from the trials suggested that diets lower in total fat were associated with lower relative body weight (by 1.6 kg, 95% confidence interval ?2.0 to ?1.2 kg, I2=75%, 57?735 participants).”

    1.6kg lower weight is pathetic. You could lose that on a trip to the can.

    (reply)
    • jake3_14  December 19, 2012

      If you can lose 1.6kg/3.5lb in a bathroom session, I think you’d need immediate medical attention.

  16. Sean  December 19, 2012

    Peter,
    I also want to thank you for sharing your empirically based insight on calling out the research community on their bluffs (yes, more than one).
    How are the medical experts (clinicians) expected to properly address the clinically significant cause-and-effect data concerning our obesity epidemic, when the ‘evidence’ is fraught with misdirection and disguise?
    Let alone convince the laymen (the public) of the efficacy, reliability or ‘trustworthiness’ of those findings?
    Can you blame the public for being utterly confused and skeptical?
    *sigh*
    So much time is wasted.

    (I’m a budding professional trying to make sense of the ‘garbage’)

    (reply)
    • Peter Attia  December 19, 2012

      Sean, this is what keeps me up at night. This is why I do what I do. We can do better than this and the excuse that it’s too tough or too expensive to do and report on research appropriately is no longer acceptable.

  17. Ben  December 19, 2012

    First, just wanna say thanks for the great work you do Dr. Attia. Answering so many comments like you do is going so far above and beyond, very kind of you. I finished taking notes (literally) on your ketosis part 1 article and will now begin the cholesterol articles as I await part 2. So, I have three questions, if you don’t mind.

    What’s your take on this Chris Kresser article? Don’t feel you need to read it if you haven’t already. I can’t figure out what my strategy should be on that. http://chriskresser.com/when-it-comes-to-fish-oil-more-is-not-better

    Which leads into my next question. It would be nice to have the ability to sort out the science myself. I’m taking notes on a 15ish page article called statistics for clinicians which is good so far. I also plan to read Bad Science. Do you have any other suggestions? Books, articles, textbooks?

    Any input to the ‘euphoria’ phenomena? While in ketosis, if I carb up at night with high GI carbs (roughly 150 carbs), and then revert back to ketosis, I find I can attain euphoria over the next 3 days at times. That is, I feel very happy and not anxious. After 3 or 4 days the feeling goes away and I’m prone to anxiety again, though nothing like I feel on a high carb diet.

    The middle question is the most important for me if you pick one!
    Thanks. Keep up the good work.

    (reply)
    • Peter Attia  December 22, 2012

      Ben, glad you’re enjoying the content. I’ll try to address your questions.
      1. This is an area that still has me completely stumped. I cannot make sense of this, but agree with Chris’ main point about the inability to properly study disease in the context of isolated nutrient supplementation. I’ve read most of the papers he cites here, and see his points, but some of them could also be interpreted another way. What to do? Well, I’m not sure. I do consume less than 3 gm/day of EPA and DHA (so not “high does”) and probably eat fish 1-2x per week. My RBC EPA and DHA levels are “normal,” for what that’s worth (I put “normal” in quotes because I don’t think we actually have a clue what normal is). I can absolutely speak to the dangers of too much EPA and DHA, so certainly over-doing it is an issue.
      2. Francis Bacon
      3. I’m not sure…

  18. Darryl  December 19, 2012

    http://www.nature.com/ismej/journal/vaop/ncurrent/full/ismej2012153a.html
    Gut bacteria responsibke for obesity ? Couldnt find a way to email him seperatly and i have to get back to work.

    (reply)
    • Peter Attia  December 19, 2012

      Very likely that gut bacteria play a role in MetSyn (and, by extension, obesity). The question is how does what we eat impact them? Certainly other factors do, also, such as antibiotics play a role, but the real unexplored area is the role of food on gut biota.

  19. darryl  December 19, 2012

    Looks like the study is included … did you read it and whats your opinion of it ?
    I look at it immediately said well they fed the guy non-digestible carbs .. which equals low carbs … which is what you called a variable right?
    So id like you to dig onto this a little as i cannot make heads nor tail of what exactly they are saying.

    (reply)
  20. Alex Li  December 20, 2012

    Hi,

    What tools I need to measure ketosis and where I can get them? Thank you.

    (reply)
  21. Colleen  December 20, 2012

    Peter: After reading your blog the past year, and others, when I see an article reporting on a study like this I can immediately pick it apart (without even reading your current post). . . so thank you. The study looks worthless to me, no more than if you cut out eating some crap and eat low fat, of course you will lose weight. What if you cut out crap and carbs and ate fat? If you took a segment of those 78,000 or so and put them on paleo style low carb diet, up to 100G carb per day or so, the results would be stunning, just as in our family this year, first we stopped consuming sugar (not crazy amounts, but more than one would think), and lost weight. But the dramatic results occurred after we cut out all the grains and beans and ramped up fat consumption. You would be looking at much more than a 3 pound difference! (Sadly to say with almost no exercise, that’s next year’s challenge).

    A 3-4 pound difference looks pathetic to me. Is that really clinically significant?

    Thanks for your blog, it is appreciated.

    (reply)
  22. Wade H  December 22, 2012

    Peter, I went to the WHI study of over 48,000 women that you speak about.

    Not noted in the description above of the results is the following from from that study,

    From the Comments-
    “Weight loss from baseline through the follow-up period was greatest among women who had the greatest decrease in percentage of energy from fat; the small number of women who increased percentage of energy from fat during the study showed weight increases.”

    http://jama.jamanetwork.com/article.aspx?articleid=202138

    Also not noted, is that while the WHI 7.5 year long study used the “goal” of having only 20% of calories as fat, the actual participants ended up at 29.8% of calories as fat. Hardly representative of the diets suggested by Dean Ornish and others in that crowd. I believe Ornish participants were closer to 10% of calories as fat.
    Certainly not above 15%, or in effect only half of what the results of the WHI report at 29.8% for the intervention group.

    While cleary there probably is a performance bias in the WHI study, it is interesting to note that even in the control group, the women who ate less fat also lost more weight relative to other women in the control group.

    As they put it in the abstract —
    “Weight loss was greatest among women in either group who decreased their percentage of energy from fat. ”
    We can’t attribute that to performance bias for those in the control group.

    (reply)
    • Peter Attia  December 22, 2012

      Wade, the authors of the WHI, when it was published, were basically criticized for a few things:
      1. The subjects were not compliant enough with the low fat, high grain, high F/V diet, seeing only a modest change from the control. Given the performance bias, this may suggest such an intervention is harder to follow than folks think, but also that their intervention methods were insufficient.
      2. Only post-menopausal women were included. I think this was necessary to get a homogeneous enough population to ask the question they were asking…but it does imply the lessons learned (reducing fat slightly and increasing grains and F/V slightly had no impact on health) only apply to this population.
      3. Some said the study was too short (median follow-up was 5.7 years, I believe) to “capture the benefit.” I think this is incorrect. If you can see a change in 5.7 years…I don’t think you’re seeing one.

  23. Boundless  December 22, 2012

    Most nutrition test/study data that reaches the popular press is based on comparisons within the context of a glycemic diet, gluten-bearing grains and all. This is such a “high noise” environment, that it’s wonder any signal can be measured at all – entirely apart from flawed techniques. It’s particularly amusing when the outcome they are trying to measure is being largely caused by factors they are entirely ignoring.

    I’d hazard that pretty much everything we think we know about food is going to have to be retested in a keto context. I’d be curious, for example, to see things like wine and coffee studied that way. Perhaps the cycle of see-saw headline conclusions would vanish, and there would be an unambiguous result.

    Meanwhile, we get studies that might as well conclude: “This investigation was based on two well-known scientific principles: observer bias and placebo effect. Needless to say, we got the results our sponsors were hoping for.”

    (reply)
  24. Dan  December 25, 2012

    I’ve been N-1 on what happens when you go back to a moderate SAD after having been low-carb for a while and it isn’t pretty. In about 3-4 months I’ve put on 20+lbs. Some of that is muscle (been doing a powerlifting type program up until 2 weeks ago), but most is flab. The biggest change was I started drinking microbrews again, had occasional sweets, and didn’t strictly avoid bread, rice, etc. I’m 6’4″, now around 205; so it’s not crisis time..but this drives home how easy it is for some of us to plump up and how low-carb may need to be more of a lifetime lifestyle change than a sporadic visit to keep weight under control. I have work to do in that dept; I previously viewed it as an aesthetic choice, but now seeing how my body reacts to even moderate amount of CHO, I’m moving on to seeing it as necessary if I want to be healthy later in life and avoid MetSyn..hard pill to swallow when society tells you to look the other way and you seem otherwise healthy to most..meaning, no one looks at me and thinks I’m obese or have health issues.

    FWIW- I’m a recovered endurance athlete who used to gulp carbs..and a recovered undiagnosed alcoholic who likely still has addiction issues with food/booze.

    (reply)
  25. Rex  December 27, 2012

    You wrote in material part: “I know many of you are awaiting Part II of the mini-series on ketosis . . . .”

    Yes, we are.

    (reply)
  26. Jim Small  December 27, 2012

    Interesting since a reasonable study comparing low carb with regular diets was done at Stanford FIVE years ago and showed Low Carb worked better. (New England Journal of Medicine.) Was that part of the Meta-analysis? I doubt it.

    In light of your comments, Peter, the obvious study would be to compare a low fat with a low carb group with comparable support: diet, cooking advice, encouragement, etc. You would have to have the counselors equally committed to their study arms, also; someone forced to counsel low carb who did not believe in it would unconsciously send all kinds of subtle disapproval messages. Another approach would be a crossover–force low fatters to counsel low carb and low carbers to counsel the low fat!

    For a future post, consider analyzing the various kinds of bias that can afflict us all and put them all in one place with short examples. The loss of critical thinking skills makes dummies of us all, even those with too much education like me. (MD and PhD from Duke, 1983…)

    (reply)
    • Peter Attia  December 27, 2012

      Jim, the study you’re referring to, I think, is Christopher Gardner’s Stanford “A TO Z” trial. It was excluded, along with a dozen other good trials because it was a weight loss trial. This meta-analysis only included studies that *specifically* studied anything but weight loss.

    • Jim Small  December 28, 2012

      So they did an analysis and concluded that low fat diets helped weight loss, but excluded weight loss trials. Makes sense to me…

    • Peter Attia  December 28, 2012

      My thoughts exactly.

    • Wade H  December 28, 2012

      Just a word about the Stanford A to Z study as comparing low carb vs low fat.

      Here is how the participants of the two of the 4 diets followed the intended guidelines.

      Those on the “low-carb” Atkins diet were suppose to aim for 20 – 50 grams of carbs per day.
      They began with their normal intake at 215 grams per day.
      At 8 weeks they were down to 60 grams per day. (not bad)
      At 6 months they were at 115 grams per day
      At 12 months they were at 140 grams per day

      Now look at the “low-fat” Ornish comparison group
      Their stated goal for comparison purposes was to have their fat as a percent of calories be at 10%.
      They began with their normal diet at 35% fat
      At 8 weeks, they were at 21% (more than double the study goal)
      At 6 months they were at 28%
      At 12 months they were at 31% (more than triple the study goal)

      Thus, using the Stanford A to Z study as a “comparison” of low-carb vs low-fat of the Ornish style is very misleading, unless you are really looking at compliance versus non-compliance as the key investigation point.
      The key advantage the Atkins group seemed to have had was the ease to stay closer to the study goals.
      Had each group been at, say, 90% compliance, then we could make some statments about the actual diets effectiveness.
      There are large groups of people out there doing 50 grams per day of carbs and 10% fat calories.
      Who knows how a dedicated group of each would come out after 12 months.

    • Peter Attia  December 28, 2012

      Wade, if you look at the 6-month data (or it may have been 3-month), when all the subjects were still closer to their prescription diet, the results hold.

      Furthermore, I’d make a distinction to your point. After the study was published Barry Sears (ZONE diet) was angry because the study suggested his diet wasn’t particularly useful. In fact, he looked at where the Atkins folks ended up (they basically were 40/30/30 at the end of the study) and said, “Look — they were on the ZONE diet by the end of the study and they did the best!” True, but not true. They only got there because they didn’t stay where they were guided. Same argument for Ornish. But don’t confused efficacy and effectiveness. You are talking about the latter, which is fair. But we can still learn about the former from this study, which is a very important take-away. The folks who ate more fat — regardless of diet nomenclature — did better (on average).

    • Wade H  December 29, 2012

      “But we can still learn about the former from this study, which is a very important take-away. The folks who ate more fat — regardless of diet nomenclature — did better (on average).”

      True, at the end of 12 months, those on (to some degree) the Atkins diet had lost about 10 pounds.
      Those on (to some degree) the Ornish diet lost about 5 pounds.
      However looking at the graphs in that study, Fig. 2, and the weight gain trajectory of the final 6 months, it appears that within 1 year, all the advantage of the Atkins group would disappear.
      I wish they had broken out and presented those few partipants who followed the original study goals.

    • Peter Attia  December 29, 2012

      The follow up version of this study (enrolling subjects beginning in April) will be much less ambiguous. It will be an epic study.

    • Jane  March 31, 2013

      I am looking forward to seeing the results of the efficacy trial. I have so many questions! A few:

      Is the research design for the trial beginning enrollment in April published? Online?
      Where is it being done? Which team(s)? In the depths of the obesity epidemic, such as the Deep South of the US? Children? (This epidemic could have such powerful effects on future populations, through epigenetics as well as culture.)
      Will interim results. — e.g. 3- , 6- month — be published? Revealed here or at NuSI.org?

      Again, thank you so much, Peter.
      Jane

    • Peter Attia  March 31, 2013

      All in time.

  27. Howard N  January 3, 2013

    Hi Peter ,
    Thanks for another great post.

    Someone else has probably pointed this out, but I was looking for the NuSI website and accidentally ended up at NuSci instead. At first I thought you had redesigned the NuSI website, but when I started reading, I thought I was losing my mind — the movie Forks over Knives was highly recommended!?! The book the Starch Solution was recommended!?! It only took a minute or two to realize the mistake and I went to NuSI, but how much difference one little letter can make!!

    (reply)
    • Peter Attia  January 3, 2013

      Shouldn’t take too long to figure out that’s not NuSI…

  28. James  January 3, 2013

    Hi Dr. Attia, love the blog, I’ve learned a lot and enjoy reading your posts. I know given your personal experience you have said you believe exercise is not effective in weight loss (off thread topic I’m sorry). I assume you believe that exercise induces hunger, thus the more you exercise the more you’ll eat just to keep up with your exerted energy, (i.e. your body is trying to keep you in a state of equilibrium) and you won’t necessarily gain or lose weight (except gains from lean tissue). Do you still believe this? Do you believe this holds true whether you are insulin resistant or not?

    I simply can’t wrap my head around exercise not being a useful tool in weight lose. Obviously I believe diet is the most effective way to make changes, (more so when considering how many people would routinely exercise compared to simply changing what they eat) but I don’t see how 30-45min of light-moderate aerobic exercise couldn’t be beneficial in addition to the dietary changes.

    Let’s say someone exercises at 7PM and then eats their normal HFLC meal, (assuming they had no circulating insulin whilst exercising) is it then assumed they will eat a bigger meal because they exercised, thus replacing whatever may have been lost? Will they eat more later, because of the exercise? What if they simply exercise late enough so they sleep shortly afterward, and thus they are unaware of any hunger pains associated with the exercise? Will the fact that they ate their normal scheduled meal following the exercise, satiate them from their added hunger brought on by the exercise? Hypothetically speaking, what if they simply can ignore any hunger that might be brought on by the exercise? What if not everyone is so susceptible to increased hunger or drive to eat more from exercise?

    (reply)
    • Peter Attia  January 3, 2013

      I’m on the fence. If there is a weight control effect, it’s a fraction of that you see from dietary change. The data, when really parsed out to remove intervention effects, is not compelling. But here’s my question for you: Who cares? If you love to exercise, as I do, do it for the other reasons. If you’re only exercising for weight control, I worry you’re in tenuous relationship that may end in disappointment. If you exercise for the “right” reasons (in my opinion), you’ll be a lifer and get so much more joy out of it.

  29. Brian Wellman  January 9, 2013

    Hi Peter,
    I wondered if you had any thoughts on the recent US News & World Report that came out ranking the best diets of 2012. No surprise (even if wrong) in that low-fat diets that recommended avoiding red meat made the top of the list. Meanwhile Atkins and Paleo-like diets were toward the very bottom.
    Hope all is well. Really enjoy the blog!
    Brian

    (reply)
    • Peter Attia  January 9, 2013

      Look at criteria for ranking…compliance with “formal guidelines” gets most points.

  30. Aaron  January 14, 2013

    Hi Peter –

    Thank you so much for the site. I hope you don’t mind, but I wanted to point something out that bothered me while reading the article. It seems like your goal was to discredit the study mentioned, and to raise a healthy amount of skepticism in your readers’ minds about the validity of the study’s claims. To do that you began by attacking the meta-analysis as a methodology.

    The key takeaway in the first part of the article is that meta-analyses are of dubious value because of the principles of the endeavor, regardless of the quality of their construction. If your point was to invalidate the study based on its methodology, I think you could have done more to reinforce that point. Currently, you do not provide a data-based refutation of meta-analyses, which would have strengthened your attack.

    Although I don’t mean to nit-pick, you have used meta-analysis in your JumpStartMD videos on the role of dietary fat in weight loss as a point supporting LC diets. It doesn’t follow that you would raise an attack on the meta-analysis as a methodology to detract from its validity when the conclusion of the paper is in opposition to your own views, but withhold that objection when the meta-analysis supports them.

    The reason I am writing this critique of your article is because I would prefer that you not raise the issue of the invalidity of meta-analyses unless you are going to substantially support it. I object to it because many of your readers may not have the necessary experience to form their own views on the subject. Because of the excellence of the other posts on the site, and because of your general rigor and intellectual acuity, you may have a halo-effect of acceptance that extends to even weakly supported points. Since one of your related goals is to stop the spread of bad science and to arm your readers with better tools for detecting bad science, I felt this may slightly violate your own principles.

    I still deeply appreciate the work you are doing on this site, and I hope my small critique does not offend you in any way, as that is not my intent.

    Best,
    Aaron

    (reply)
    • Peter Attia  January 15, 2013

      Thanks, Aaron. I’m not offended at all, and appreciate your comments. Though I may not have made the point clearly, this is my point: There is nothing wrong with a meta-analysis. But a meta-analysis is only as good as the sum of its parts. A meta-analysis of good studies has the potential to be good. A meta-analysis of flawed studies can not be good. In this specific cases, virtually every one of the studies suffered from a well-documented bias — a fundamental flaw that invalidates that conclusions of of the meta-analysis authors — called performance bias. It’s important to note that this does not mean the studies themselves were flawed! If the individual studies were looking to ascertain the impact of counselling + diet, then performance bias it not an issue! It’s only an issue for the meta-analysis, because of their hypothesis and what they sought to test.

      So I stand very firmly by my assertion. This meta-analysis is fundamentally flawed, specifically because it claimed to examine the role of a low fat diet (vs. a low fat diet + extensive counseling).

  31. Dan  February 4, 2013

    Hi Peter,

    How would you respond to this article?
    http://www.tcolincampbell.org/courses-resources/article/lowcarbohydrate-diets-health-advisory-health-risks/?tx_ttnews%5BbackPid%5D=76&cHash=2263a1b6e98428f898c1111fc7d14eb3

    I am inspired by your health improvements and your desire to discover what foods lead to optimum nutrition. It is something I slso try yo do but do not have the scientific or medical background.

    I am wondering what you see wrong with the article I linked to. Thanks!
    Dan

    (reply)
    • Peter Attia  February 5, 2013

      My entire blog is the response to this. CF: observational epidemiology. Read the post I wrote last year on red meat.

  32. Sherwood  February 18, 2013

    In your blog entry on “How I lost weight” you present 3 pie charts showing how your diet evolved. This post should go there, but there is no ‘comments’ section on that one.

    However my understanding of the “Typical American Diet” is that he is somewhere between chart 2 and chart 3 already, getting 40-50% of his calories from fat, and the rest as a roughly even split between protein and carbs.

    There may be merit in showing how PA’s plan is different from the TAD. Showing the TAD pie chart with carbs split into sugar, high glycemic carbs, and low glycemic carbs may make the distinction more clear.

    ***

    Another set of blogs I’d like to see: How do we measure progress if we aren’t in the position to get all these tests done. (AFAIK I don’t think that LDL-P is even available here.)

    The other issue that comes up if we are looking for heart health, weight loss, and working endurence: How to do this without going broke?

    ***

    There are several outfits, some diets, some just data companies, that you can record everything you eat on a daily basis. ( I know your attitude toward observational studies. My training was in astrophyics and geology. Our experiments are hard to budget for.) However: It would seem to me that taking participants who have made good records for a year, and enrolling them in a study, much like the framington study where you tried to nail down as many factors as possible, might yield some interesting things to check.

    ***

    (reply)
    • Peter Attia  February 18, 2013

      According to the best data available from NHANES, the average American consumes 15-16% of their calories from protein; 50-55% from carbs; the rest from fat. Formal guidelines call for more carbohydrate, less fat.

  33. Ana B.  March 1, 2013

    Dear Peter, thank you so much for the work that you have been doing in this area! I have great hope for NuSi and will continue to watch its progress. So this N of 1 is baffled about what’s been happening since I finetuned my eating habits to be consistent with the science you and Gary Taubes have so effectively presented. I started from having been on the South Beach Diet, so my labs were pretty good by then (the pedestrian ones, not the sophisticated ones you conduct), but I was always struggling against the pull of “the bad stuff.” Since committing further to (switching to , really, given what I’ve learned from you) a LCHF lifestyle, however, my labs have remained great, I feel great, with tons of energy, and I don’t struggle with “the bad stuff” at all, BUT my number weight has gone up significantly (20 lbs in 2 years) and, at least according to Ketostix, I’ve never been in ketosis (maybe that’s due to my drinking a glass of wine per night?). I am not asking for an analysis of what’s going on; I just want some ideas on what to “experiment with” to see what might be driving the weight gain (oh, I should also have said that I went from being very toned through weekly personal training sessions to almost no exercise at all due to a change in jobs). Any feedback would be appreciated.

    (reply)
    • Peter Attia  March 1, 2013

      Impossible to troubleshoot like this, but one glass of wine each night, under most circumstances, should not interfere with ketosis, if that is what you are striving for.

  34. Ana B.  March 2, 2013

    I know, so can you suggest a type of person to troubleshoot with? My current doctor is on the traiditional nutritional camp, and I’m not sure how to search/find someone withiin this nutrition belief system. Any websites/databases with lists of doctors or other types of professionals? Thank you in advance to anyone who can offer help.

    (reply)
    • Peter Attia  March 3, 2013

      Perhaps Jimmy Moore’s website for a physician, or look for a health coach who understands carb reduction?

  35. Joe  March 26, 2013

    Thank you, Peter, for this provocative and engaging website. I recently read both you and Gary Taubes and found myself extremely compelled by the evidence you have presented for ketogenic diets. I have adopted your approach and am currently down 22 pounds and I no longer experience violent swings in energy. Regarding fats: I have begun cooking with lard and was disappointed to see that commercial lard is almostnalways hydrogenated. A 13 g serving has about .5 g of trans fat. Is this within an acceptable range or should I dump the lard and opt for something else?

    (reply)
    • Peter Attia  March 27, 2013

      Not really sure. 0.5 gm is pretty small. You may wan to try coconut oil, butter, or ghee.

  36. Felicia  July 1, 2013

    Hey Peter…love your blog. I have a question. I had a biliopancreatic diversion with duodenal switch 4 years ago. They removed about 80% of my stomach and rearranged my intestines to aid in weight loss. As a result, I only absorb approximately 60% of the protein that I eat (and only about 20% of the fat that I consume!). If I weigh 70 kg and 1.5 g per kg means I should consume about 105 g of protein, would you suggest that I shoot for about 175 g of protein to account for the malabsorption? I am trying to stick to 50 carbs or less per day, but my fat has been no where near the amounts that you have been consuming. It has been at about 135 g per day. Is it essential to up the fat grams to achieve nutritional ketosis? Add in heavy cream, butter, etc. so my overall numbers go up? Thank you for your time…I appreciate all that you do.

    (reply)
  37. Dan K.  July 9, 2013

    Peter, I understand your view that a low-fat diet is not necessary for weight loss. However, I’m having difficulty finding support on your blog for the proposition that a high-fat diet is more optimal? Once someone like myself takes the first four steps you’ve recommended in the “How can I lose weight?” section on your blog, what are the reasons for increasing fat intake? And why should someone limit intake of protein?

    As a general comment, your blog has been eye-opening for me, and since first reading it only a week ago (after a friend shared your TED talk), buying Gary Taubes’s book, and adopting some of your recommendations, I have experienced noticeable improvements to my health. Many thanks for your contributions.

    (reply)
    • Peter Attia  July 10, 2013

      It’s really a function of what you’re optimizing for. I can’t really answer your question directly, Dan, without much more context. For what it’s worth, most (though not all) studies that pit fat-restricted diets versus carb-restricted diets find the latter to have superior results with respect to weight loss, BP control, and most biomarkers of disease risk. Some have found no difference, though I argue they found no difference because of poor study design which did not create sufficient dietary discrimination.

  38. Dan K.  July 18, 2013

    Hi Dr. Attia, thanks so much for your response (and recent post on fat flux). Can you explain what happens to dietary (and specifically saturated) fat consumed that is not used as energy? Is it absorbed into the body but not into the fat cells? Or possible excreted out? Perhaps I’m not articulating this question the best way, but basically I’m trying to figure out how the body processes saturated fat, and why for some people consuming more fat would be better than less.

    To provide context, I am experimenting with ketosis with the goal of losing 6-8 pounds and eliminating my constant sugar cravings (and daily highs/lows from my former high carb diet). Now my question is “to fat or not to fat,” (e.g. South Beach or Atkins). Many thanks again for your important contribution in this field!

    (reply)
    • Peter Attia  July 19, 2013

      If not used as energy, it’s stored as fat (via RE process) or shed from the body in the GI system.

  39. sergio ojas  August 11, 2013

    Hi there is another study I encountered in researching ketosis that links ketosis to cancer, called “Ketones and lactate increase cancer cell “stemness,” driving recurrence, metastasis and poor clinical outcome in breast cancer: achieving personalized medicine via Metabolo-Genomics.” http://www.ncbi.nlm.nih.gov/pubmed/21512313.
    Does this mean a ketosis diet is not effective for breast cancer patients and those at risk for breast cancer?

    Thanks

    (reply)
  40. Komal  August 21, 2013

    I was very impressed by your seminars and articles but am very confused by the contradicting ideas that you share and those from the plant-based group who are for starch and vegetable based diets with no fats and meats and seem to argue that they have a lot of science behind why that is the way to go and yours is not. Can you please make an article or a response video to that?

    (reply)
  41. Rand  August 29, 2013

    Peter,

    The following link is to an old (2002) study, but seems to validate your experience with nutritional ketosis: a carbohydrate-restricted diet resulted in a significant reduction in fat mass and a concomitant increase in lean body mass in normal-weight men. http://www.ncbi.nlm.nih.gov/pubmed/12077732

    (reply)
  42. Cathie Saines  September 19, 2013

    Excellent article Peter. I love your work and appreciate the data you share.

    To everyone’s health!

    Cathie.

    (reply)
  43. Mark  September 29, 2013

    Good artical tons of data.
    I have done the Keto diet a few times, high fat, low to no carbs. From personal experiance it works wonders. I can lose @10lb in 2-3weeks. but , you really start missing carbs with in the first few days

    (reply)
  44. Brody  September 29, 2013

    New to your blog and really enjoying the new information and perspective.
    As Michael Pollan points out in In Defense of Food, the whole idea behind these studies is pretty flawed. You put people on a low-fat diet, but you can’t change just one variable. When you lower fat, you’re increasing protein, or carbs, and then if the diet is working for some people – there is no way to determine if it’s because of the increase of protein, or maybe due to the extra fibre you’re eating (or a combination of many things.) et cetera.
    We want to simplify things down to fat = bad and ‘eat this, not that’ when food and nutrition is incredibly complex .

    (reply)
  45. hem rid  December 28, 2013

    If you really wanted to understand the impact of a low-fat diet on weight loss or some better marker of actual fat loss, it seems that actually looking at trials where this was being tested might be a better place to look.

    (reply)
  46. Erika  February 19, 2014

    I am just blown away- found you on my daily ted talk- I have had PCOS weight dramas and all the other insulin issues that go with it dismissed by Drs my entire life. I’m taking Metformin 1700mg a day, so the effect that has is great for some things, like regular ovulation, but I still do not seem able to move weight- and in recent high-stress times I put on those 10 kgs I have killed myself over the last year to loose. I need a user-manual and easy steps- talk to me like I’m 5- what book do I need to start implementing meaningful diet changes? I already cut out sugars- and fruit. The nutritionist at my diabetes clinic meetings hates me. I cook in coconut oil and she freaks out and says this is why I’m fat. Hopeful and glad to have found this blog- best wishes! E

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  47. Karen  February 22, 2014

    Peter, thank you for putting this together.
    I want to know if it’s good to add drinking tea in the diet plan. There are saying tea is a great method for weight loss, can you please check http://bestteaforweightloss.com/ and give some thoughts?
    I also point my name to the site to avoid being removed in this comment.

    Thank y ou

    (reply)
  48. Mike  June 7, 2014

    Sadly each study seems to disprove the last. Or perhaps we are just constantly learning?
    I recall thinking in Science class at College that science is by no means perfect and not at all complete, so we need to take everything we hear and learn with a grain of salt!
    Mike

    (reply)

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