Comment by Gatsky | Hacker News Reader

Comment by Gatsky | Hacker News Reader

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Just because it boosts GH doesn't mean you build muscle. Undoubtedly, fasting has positive metabolic benefits, but building lean muscle mass isn't one of them. The studies I have seen about regular fasting and muscle mass generally show loss or at best maintenance with exercise. Generally you will be catabolising muscle when you wake up from sleeping, until consuming sufficient protein. This is why body builders eat so often, and also try to have some slow release protein before sleeping.

You are right that exercise isn't a good way to lose weight, I am not talking about that at all. By magnitude of benefit I am talking about mortality/longevity/frailty, not weight loss. That's what really matters.

The relationship between body weight and hard clinical outcomes is complicated and not monotonic (obese pre-menopausal women are less likely to get breast cancer, to provide one example). Additionally, asian people suffer from the skinny-fat phenomenon, where they are not obese but have metabolically pernicious visceral fat.

The post you are responding to does not make the claim that it builds muscle, nor does it make reference to lean muscle mass... It says "preserves" muscle (comparable to "maintenance" as you suggested).

I'm not buying it. Muscles use energy even while at rest so in the case of an emergency I'm sure the body will first remove the useless consumption of unnecessary muscle mass than to start tapping the reserves.

In what world would the body prioritize consuming "unnecessary muscle mass" (the thing you need to hunt down and kill food) over fat, which is by definition energy stored for this exact scenario?

Muscle simply doesn't consume much more energy at idle than fat does but is far more useful and far less calorie-dense. A pound of muscle burns 4-6 calories per day at idle vs a pound of fat which burns 2-3 calories. Basically the same.

>In what world would the body prioritize consuming "unnecessary muscle mass" (the thing you need to hunt down and kill food) over fat, which is by definition energy stored for this exact scenario?

I would predict that the body would consume both, in a ratio that shifts from fat towards muscle as energy supplies dwindle, in an attempt to stretch the final reserves by reducing consumption.

HGH promotes breakdown of fats [1] and inhibits the breakdown of muscle [2]. Since fasting significantly increases HGH, that would all make sense.

[1] https://pubmed.ncbi.nlm.nih.gov/11086655/

[2] https://diabetesjournals.org/diabetes/article/50/1/96/10905/...

>in a ratio that shifts from fat towards muscle as energy supplies dwindle

it's in fact the other way around. The body first reduces what is not used (unused muscles) and then energy reserves.

[citation needed]

>citation needed

common sense

Try to build some muscle and get shredded... should be very easy with your methode/logic

With respect 'common sense' is frequently wrong which is why I was asking for some study, evidence, documentation etc. Along the lines of the articles I provided.

If you just want an anecdote it certainly works for this guy [1]. And he, in turn links out to a ton of studies.

To be clear at no point did I claim that fasting would grow muscle, I don't have any data to back that up. What I said was that your body will preserve muscle when fasting because muscle is useful and fat is not. This is backed up by the articles I cited indicating significant HGH increase, and articles citing the role of HGH as inhibiting the breakdown of muscle and promoting the breakdown of fat.

Your claim requires evidence.

[1] https://leangains.com/

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