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The personal blog of Peter Attia, M.D.

Why we get fat (video)


Part one of the interview I did for Open Water Source – although I talk about many topics that will interest non-swimmers and non-athletes. (View the other videos in this series.)


Open Water Source: Peter, in layman’s terms, can you describe the current debate in nutrition regarding why we get fat?

Peter Attia, MD: Sure. This is probably one of the most misunderstood concepts in all of, not just nutrition, but probably health. The current or conventional wisdom says we get fat because we eat too much or move too little. I believe that that’s actually got the cause and effect backwards. I’m obviously not alone in thinking this, but I believe that it’s the opposite. I believe that we eat too much and/or move too little because we are getting fat.

Let me illustrate that with a couple of examples. I have a three-year-old daughter. At times, she goes through phenomenal growth spurts. And when she does that, she starts eating like crazy. Other times, she eats like a bird. Is it the case that she’s growing because of how much she’s eating? Or is she eating that much because of her drive to grow? I believe, in her case, growth hormone, which is being secreted by her pituitary gland, is driving her to grow. And as a result of that, she is eating more calories than she’s expending during that period of her life.

Let me give you another example. When a woman is pregnant, she tends to go through profound periods of changes in how much she eats. And it’s not just to gain weight in the form of the fetus itself. It’s actually to put on more fat, specifically, so she can nurture that fetus. Is she gaining that weight because she’s eating so much? Or is she eating so much as a hormonal drive to gain that weight to support the fetus? Again, I think in the case of a pregnant woman, it’s pretty obvious.

I argue that obesity is the same thing. People who are obese are not obese because they’re eating too much or not moving around enough. Those things are the result of a hormone that’s driving them to do that. And in the case of obesity, I believe that hormone is insulin. Just as in the case of a child, that hormone is growth hormone.


About the Author:

Peter Attia, M.D., is a physician in private practice in NYC and CA. His practice focuses on longevity and healthspan. His clinical interests are nutrition, lipidology, endocrinology, and a few other cool things.


  1. Fiona Ritchie  February 12, 2012

    I’m really heartened to read your blog Peter. I live in the UK & I’ve battlled my weight for years. After reading Gary Taubes’ books I embarked on a low carb diet & lost over 60lbs. I felt & looked brilliant and I was happy but because of my diet being opposite to the accepted wisdom over here I came under a lot of pressure from family & friends & so I’ve allowed carbs to creep back into my diet. The result is I’ve now put back about 16lbs & I’m finding it much harder to shift although I’m trying. It’s just so good to have some further corroboration of what Gary advocates to show my family so that hopefully they will help & support me rather than trying to undermine my efforts. One thing I’d like to ask is, do you ever consume alcohol? I do enjoy wine at the week-end & I’m wondering if that is slowing things down for me. Many thanks.

    • Peter Attia  February 12, 2012

      Fiona, I appreciate your struggle, and it illustrates how much of social component goes into changing your life. I am sure this is no different that a former smoker living with their family of still-smokers. I drink a glass or two of wine per week. Low carb alcohol (like dry wine) does not really inhibit ketosis in any way, but it does not help with fat mass and dyslipidemia. It’s really about the trade-off(s) you’re willing to make.

    • Alexandra M  June 17, 2012

      A bit late to ask, but is that the Fiona Ritchie who hosts the “Thistle and Shamrock” radio program?


  2. Clarice Perkins  February 25, 2012

    I’m wondering if you can comment on how low fasting serum insulin levels need to be in order to facilitate fat burning? What is optimal?

    • Peter Attia  February 25, 2012

      Very complicated and highly variable. As a general rule, the lower the better, but if you’re asking, for example, at what serum insulin concentration does the body shift primarily to beta-oxidation, this is highly variable.

  3. GaryP  June 16, 2012

    Just noticed that the link you have above for the other 24 videos does not appear to work. It goes to the home page of your blog instead of the videos.

  4. Lianda  August 17, 2012

    I’m wondering if you have worked with people who maintain very low carb eating (and even completely gluten free), and still don’t drop weight? Also, I’ve found similar complaints in this population: heartburn when eating fats, very slow digestion, constipation, muscle cramping and excema are among the complaints I’m hearing.

    • Peter Attia  August 18, 2012

      Absolutely. The key is starting from a place of judgement, but then being willing to alter the plan if it’s not working. This assumes, of course, that the plan was well-implement. This is not a given and, actually, is more often the cause of failure than something else. But, as Christopher Gardner and David Ludwig, among others have shown us — individual variation is a legitimate issue.

  5. Dawn  December 3, 2013

    I have a 7 (turned 7 in October) year old son with a growth hormone deficiency. He was growing well and was 75th percentile on the growth chart and then something happened after he turned 4… The problem was slowly discovered and finally after testing- which he failed… He was diagnosed and has been taken growth hormones since June. I follow the Ketogenic diet. My son is on a gluten free diet- but I don’t have him on any other restrictions. What are your thoughts about growth deficiency in children? Any recommendations?
    Thank you

    • Peter Attia  December 3, 2013

      Dawn, I’m not an expert in pediatric endocrinology.

  6. garry  June 14, 2014

    dr.attia,i am a 61 yr old male I have been following the no carb diet i just saw my doctor today,my bllod pressure was ver ygood .even with meds it would still be high,he did not like the diet,but he said if I wanted to try it ,having lost another 7 lbs since only being on it for a week,i have been cutting the sugar before ,but now I am adding the fat,and carbs from leafy vegs no carbs.my blood sugar 2 hrs after eating breakfast,3 eggs spinish and mushooms was 138 he said that was good,i1 month ago it was 135 fasting,i would like any more info you can give me,thanks.

  7. Lloyd Ignacio  June 13, 2015

    I am a Type 1 diabetic and require insulin. So how does that affect losing weight? I average about 200g of carbs per day and have gained some weight after being on a low-carb, low-calorie diet.


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