February 13, 2023

Nutritional Biochemistry

#242 – AMA #44: Peter’s historical changes in body composition with his evolving dietary, fasting, and training protocols

“Trends matter. You're treating what you see, but you're mindful of the trends.” —Peter Attia

Read Time 26 minutes

In this “Ask Me Anything” (AMA) episode, Peter reviews the last 12+ years of his DEXA scan results revealing the changes to his body composition, lean muscle mass, visceral adipose tissue, and more. He explains how his body composition and blood biomarkers were impacted by the various dietary approaches (ketosis, fasting, high protein, etc.) and training protocols (primarily endurance, primarily strength training, etc.) he has undertaken over the years. Furthermore, Peter explains his planned approach moving forward following his most recent DEXA scan in late 2022.

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We discuss:

  • DEXA scans and other methods for tracking body composition [2:30];
  • Importance of tracking data over time to see trends [10:15];
  • DEXA scans in 2011: swimming, lifting, and a carb-restricted diet [12:45];
  • DEXA scans 2012-2014 during Peter’s time on a strict ketogenic diet [18:30];
  • Blood biomarkers for evaluating metabolic health [25:15];
  • DEXA scan in 2020 after several years of regularly engaging in time-restricted feeding and prolonged fasting protocols [28:45];
  • DEXA scan in 2021: shifting focus to adding muscle, high-protein diet, and more strength training [40:00];
  • DEXA scan in early 2022: eating additional calories and adding blood flow restriction (BFR) to his workouts [44:45];
  • DEXA scan in late 2022: a dramatic change following shoulder surgery, and the impact of stress [48:30];
  • Peter’s approach moving forward following his most recent DEXA scan [59:15];
  • A rundown of the various nutritional methods of energy restriction [1:06:15];
  • Current thoughts on fasting and key takeaways [1:09:45]; and
  • More.


DEXA scans and other methods for tracking body composition [2:30]

In this conversation, Peter will review the last 12+ years of his personal DEXA results

  • See AMA #40 for more on DEXA scans and how Peter goes through results with patients
  • During the last 12 years, Peter’s nutritional and training approach has varied pretty drastically
  • For instance, growing up, his main thing was boxing – a very, very weight driven sport – Every ounce of non-essential tissue you carry into the ring is problematic


  • Back in his younger, boxing days, he relied on calipers for body composition
  • It’s not the most objective standard and it’s highly dependent on the skill of the individual doing the test
  • That said, a person who really knows what they’re doing with caliper’s is awfully good and pretty accurate

Hydrostatic testing

  • Fast forward to Peter’s thirties, he was monitoring body composition using hydrostatic testing
  • This is where you’re weighed while dry and then weighed again underwater under the conditions of full exhalation 
  • The ratio of those two weights, and the use of Archimedes’ principle, would basically allow them to deduce how much of your weight was fat
  • That turned out to be a pretty inaccurate way to go about doing things
  • For no other issue, highly dependent on basically how much air is left in your lungs at the point of exhalation

DEXA scanning

  • Late 2011, Peter switched over to DEXA scanning
  • For all intents and purposes, DEXA is the gold standard
  • It’s a type of x-ray that scans your body that effectively divides tissue into the following buckets very accurately; bone, fat, “other”
  • The “other” is mostly muscle, but of course it’s also your organs 

What DEXA is looking at:

  • It’s very good at giving total body fat because it’s very accurate at measuring fat
  • Total body fat divided by total body weight is your body fat percentage
  • Peter is adamant that his patients get DEXAs scans at least once a year

When going through the results with them, he explains basically the same four things

  • First, the least interesting metric is your body fat percentage (which is what most people care about)
  • Secondly, visceral adipose tissue (VAT), which is one of the compartments of fat that is outside of the subcutaneous stores 
    • If we’re going to put excess energy away, we want it to be in subcutaneous pockets of fat.
    • As our capacity to store fat there get stretched, we begin to spill over into other places

{end of show notes preview}

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  1. This was such a great conversation and a wonderful deep dive on Peter’s numbers throughout the years. There was one very small element that was missing for me. I was really curious to hear Peter talk about how he felt at these different stages. Does he recall when he felt the best? Completely subjective of course but would love to hear about when he felt the best and how that compared with what his numbers were. Thanks for all you do! DK

  2. Found this helpful. Thanks for sharing your experience. Got my first DEXA scheduled for tomorrow !

  3. No clue what the ressies pieces thingy is. I know reeses peanut butter cups thats all

  4. For what it is worth, I am not familiar with Reese’s Pieces. I don’t eat candy or any sweets. I haven’t had dessert in 50 years.
    However, my weakness is really good bread…especially sourdough bread.

  5. Peter mentioned his labs post his more relaxed (dietarily speaking) phase. How did CGM look during this time?

  6. Peter and Nick: First of all, it’s not pronounced “Reesey Piecey” or “ReesEEs PiecEEs”. It’s Reese’s Pieces. Both words rhyme with ceases, not feces. (I’m surprised Nick was pronouncing it wrong if he actually heard of it before. 🙂 Was everyone on that film set pronouncing it wrong too?) Secondly, did neither of you ever see the classic movie E.T.? Reese’s Pieces were E.T.’s favorite candy and were a key part in at least a couple scenes. They did a massive marketing campaign back in the early eighties with this after the movie came out. Reese’s Pieces ads were everywhere! (Maybe not in Canada? 🙂)

    Seriously, though — Great episode!

  7. Great episode. I’m wondering what additional effect Peter thinks his rapamycin protocol may have had on these outcomes.

  8. This discussion brought up the interesting detail about beta-hydroxybuterate competing with urate for excretion in the kidneys, which may be a key issue for me. I tried googling this to learn more but have not found any good resources yet. Can anyone direct me to more reading, especially regarding what a strategy might be that takes advantage of the weight loss benefits of a low carb diet and yet not elevating urate, perhaps by keeping carbs low but not low enough to enter ketosis??

  9. 71 years old, and I never heard of the Reese’s non-peanut butter candy. Also, I’ve never had one of the peanut butter cups. I like chocolate, just not attracted to the combination.

  10. A couple humorous misses: (1) When Peter says he doesn’t have a sweet tooth, he should be reminded that he has a reputation for eating discarded pie out of the trash the day after Thanksgiving. (2) When Peter says Frosted Mini Wheats are the most ridiculous cereal invented, Nick missed a callback opportunity — he could have disagreed with Peter and said, you probably won’t believe this but “Reese’s Puffs” are a breakfast cereal which is completely ridiculous.

  11. What a silly diversion the question of Reece’s Pieces took me on. I thought Nick said “reesy peicy” or something like that (which I had never heard of). So I googled it and believe it or not, there is a TikTocker named reecy peasy – bizarre and disturbing to be sure. I had heard of Reece’s Pieces, but thought they were the mini version of peanut butter cups. Had no idea there was basically a Reece’s version of M & M’s…. but then M & M’s makes a peanut butter version too!
    Good AMA, especially interesting learning about your fasting results.

  12. My Dexa actually gives LMI and ALMI, not FFMI and ALMI.
    (L=without bones, FF = with bones)
    I have to calculate FFMI myself.
    I wonder what anyone reading this gets in their report ?

    Also, my Dexa calculate body fat as a percentage of my scale weight (wich is superiori to my DEXA total mass), is it the case for everyone ?

  13. Is there a place where we can easily convert our results into Z and T-score percentiles ? The graphs aren’t the most precise.

  14. I believe the changes between 2014 and 2020 would likely be due to being scanned on two different DEXA systems. I own 19 DEXA systems. Since scanning myself on my first system in 2006 I have seen that even using the same manufacturer every DEXA we receive it gives a different body composition measurement for lean mass and fat mass. Sometimes the difference in BF% was +/-10%. Always scan yourself on the same DEXA.

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