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Comment by volker48 | Hacker News Reader

I feel like IF would be detrimental to maintaining muscle mass during a cut. You really want to keep a steady stream of amino acids to prevent catabolism of muscle tissue even when reducing total caloric intake. Usually you cut fat first during a cut. You want to keep carbs to fuel your workouts and you want to keep the protein flowing to prevent muscle loss.

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From my limited knowledge of human physiology .I don't think 24h is enough to trigger catabolism. You still have some fat reserves, and if you exercise/lift during the cut, you probably will even gain muscle. YMMV

Supposedly IF works badly for women because they enter catabolism more quickly than men. I think I even read a study about it - of course I can't find it now.

The word "trigger" is not really useful in this situation because catabolism is not triggered, it just means muscle breakdown is happening at a higher rate than muscle synthesis (both of which are constant). This happens under a lot of different situations, and can temporarily go back and forth a lot. You certainly enter net catabolism long before your fat reserves are depleted (else cutting would be simple: just stop eating until you're pure hard muscle).

There are ways to temporarily spike muscle synthesis, and one of them is eating a protein rich meal. This specific mechanism has a refractory period in the order of magnitude of hours. Intermittent fasting robs you of the ability to spike muscle synthesis as many times per day as you could otherwise.

This effect is not massive. Your body is pretty good at optimizing this stuff. But when you are cutting, in particular, or trying to bulk without putting on significant fact, these minor optimizations can add up.

Fat reserves won't help prevent muscle protein breakdown. The only way to help prevent muscle catabolism is by consuming protein, which if you are fasting you aren't doing. If your goal is to lose weight while maintaining as much muscle mass as possible it doesn't seem like IF would be the optimal choice for that. Its not physiologically possible to have muscle protein synthesis exceed muscle protein breakdown unless you consume protein. The body cannot produce essential amino acids and must obtain them from the diet.

That's the standard recommendation from sports nutrition texts, and I've certainly found it to be very true for myself. Over many cutting cycles as a strength athlete over the years, I always lost high ratios of muscle:fat during IF-style cuts, and augmenting with protein intake during long breaks between meals has made a tremendous difference despite my advancing age.

Well, you have to make choices at some point. If your goal is to absolutely maximize muscle gains, then fasting in general may not prove to be beneficial for this particular goal.

Or it may prove beneficial, who knows. I'm not sure if any research exists on this topic. But intuitively I agree with you, maintaining large amounts of muscular mass requires a lot of nutrient input.

There are plenty of places that advocate it during a cut, that's why for something like this only real studies can prove if it is more effective or not during a cut.

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