Fasting & protein: the impact of fasting on muscle mass

This video clip is from Ask Me Anything (AMA) #32 — Exercise, squats, deadlifts, BFR, and TRT, originally released on February 21, 2022.

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Show Notes

The impact of fasting/calorie restriction on muscle mass and the potential tradeoffs to consider [49:45]

How do you think about the tradeoffs between calorie restriction/fasting and muscle building for a person from a longevity perspective?

• The older you are, the more important it is to emphasize anything that’s going to allow you to maintain and build strength and maintain muscle mass
• Peter is very reluctant to put an excess fasting routine in place for somebody that’s not very heavy
• That gets to the second equally important consideration, which is the big, big part of this is body composition
  • If you’re talking about somebody who’s got 35% body fat, insulin resistance, I think fasting’s a very effective tool and it’s okay that they’re going to probably lose a little bit of lean mass, because they’re probably going to lose more fat mass along the way
  • If you’re talking about somebody who’s kind of lanky, Peter would lean towards not fasting so much and if you’re going to fast do it intermittently — e.g., maybe once a quarter you do a short fast for three days 
    • But most of the time should be really focused on building

“As you get older, I think building becomes more important. The leaner you are, building becomes more important.” —Peter Attia

Importance of getting enough protein in the context of fasting/building muscle

Nick asks Peter: A lot of times people interchange the word fasting with other things. So when you said earlier you went to an excess fasting regimen, what is that? Are you talking 12 hours, 24 hours, 72 hours? How do you think about that?

• we really don’t know what’s long and what’s short for a fast, but we do know the extremes
  • For instance, we know 12 hours is not a fast and we know that five days is a fast
• Does one meal a day constitute fasting? ⇒ “I don’t think so”
  • The problem with one meal a day for most people, if they’re trying to put on muscle mass, it’s pretty darn hard to eat two grams per kilo of protein in one sitting
  • OMADs and things like that are generally going to come at the expense of muscle mass—Not because muscle protein synthesis can’t take place if you’re smart about where you target and time your exercise, but because I simply think most people are protein deficient when they do it
  • it becomes a bit of a protein sparing diet
  • Again, OMAD is a great idea if you’re overweight and insulin resistant, not a great idea if you’re lean.