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Fasting ramps up metabolism

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Science Daily has an article  "Fasting ramps up human metabolism, study shows" at  https://www.sciencedaily.com/releases/2019/01/190131113934.htm

"going without food may also boost human metabolic activity, generate antioxidants, and help reverse some effects of aging."

"results revealed 44 metabolites, including 30 that were previously unrecognized, that increased universally among subjects between 1.5- to 60-fold within just 58 hours of fasting."

" various metabolites whose quantities decline with age, including three known as leucine, isoleucine, and ophthalmic acid. In fasting individuals, these metabolites increase in level"

"authors suggest that these antioxidative effects may stand as the body's principal response to fasting, as starvation can foster a dangerously oxidative internal environment.  ... fasting might boost production of several age-related metabolites, abundant in young people, but depleted in old."

 

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I was watching a video that also mentioned fasting increases metabolism which I thought was an error until I actually looked into it...

 

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If you look across species, fast metabolism is not necessarily negatively associated with longevity, same for body temperature. Sometimes people explain mice being short lived on grounds of fast metabolism. But that doesn't hold for all species. For example, birds have generally very fast metabolism, huge rate of energy use (they eat a lot!), and high body temperature, yet can be very long lived (see: various parrot species that can live longer than humans). Furthermore, the size rule also does not apply perfectly. Certain whale species (mammals) certainly live longer than humans (as do sharks, not mammals), but elephants don't. At the other end, smaller species certainly can live longer than humans: birds (parrots again), reptiles, crustaceans etc. - all quite small and longer lived than humans. In birds, even tiny species like hummingbirds which are some of the tiniest creatures, have an unbelievable metabolic rate (a record, I believe), and live much longer (8 years) than f.ex. mice which are comparatively much larger with not as fast metabolism. Even for rodents, size is not determinative - see mole rats (30 years).  

So there certainly are physiological examples of organisms large and small living long on a fast metabolism, running hot, with huge energy turnover. 

There is no contradiction between faster metabolism even during fasting and longer lifespan - biology is full of examples.

Here's an interesting article on birds:

https://lafeber.com/pet-birds/birds-live-long/

They get plaque (atherosclerosis), heart, lungs and kidney problems just like humans, arthritis, cataracts, gout, cancer etc. - and weirdly enough are considered *senior* at relatively young ages (30 or so), but go on to live to 120 or whatnot - so imagine you're an old man at 30 but go on to live to 120. Weird.

Edited by TomBAvoider
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2 hours ago, TomBAvoider said:

If you look across species, fast metabolism is not necessarily negatively associated with longevity, same for body temperature. Sometimes people explain mice being short lived on grounds of fast metabolism. But that doesn't hold for all species. For example, birds have generally very fast metabolism, huge rate of energy use (they eat a lot!), and high body temperature, yet can be very long lived (see: various parrot species that can live longer than humans). Furthermore, the size rule also does not apply perfectly. Certain whale species (mammals) certainly live longer than humans (as do sharks, not mammals), but elephants don't. At the other end, smaller species certainly can live longer than humans: birds (parrots again), reptiles, crustaceans etc. - all quite small and longer lived than humans. In birds, even tiny species like hummingbirds which are some of the tiniest creatures, have an unbelievable metabolic rate (a record, I believe), and live much longer (8 years) than f.ex. mice which are comparatively much larger with not as fast metabolism. Even for rodents, size is not determinative - see mole rats (30 years). 

Hi Tom!

Michael Rae has noted that cross species comparison is not a good idea -- comparisons should be made with members of the same species.

So the list of examples that you give above might not give much, if any, useful information as to whether or not a faster metabolism might be associated with a shorter lifespan.

My guess for the case of humans:  faster metabolic rate might be associated with being "naturally thin" -- having a low BMI even when eating ad lib -- and that this might not necessarily be a good thing with respect to longevity.

Whatever one's RMR, IMO either CRON or IF should be a huge boost for healthspan and possibly lifespan.

  --  Saul

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"Boost you metabolism" doesn't even mean anything.  It does not increase TDEE.  That's what most people mean by "boost your metabolism."  Does it result in the creation of more metabolites? Sure, I absolutely believe that anything that increases autophagy should.  But that doesn't mean what 99.999% of the population thinks "boosts your metabolism" means.

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