The curious case of low-protein diets

https://knowablemagazine.org/content/article/living-world/2026/low-protein-diet-animals-live-longer

by curmudgeon22 • 2 months ago

51 23 2 months ago

I don't know. Is there really a signal here when it comes to humans? It seems most of the arguments come from one study? Would be interesting to hear those here at HN that are smarter than me comment on this one.

derbOac• 2 months ago

I don't think I'm smarter than anyone here but I think I've read about this before; I don't think it's just one study.

There's also an emerging literature suggesting that deficits in specific amino acids are a kind of mammalian signal to start burning fat, which might also be related. Cysteine is one, which might also explain why plant-based diets are healthier all other things being equal, because plant proteins tend to be lower relatively in cysteine. So it might not be proteins in general whose restriction results in longevity increases, just cysteine-rich proteins.

For example:

https://www.nature.com/articles/s41586-025-08996-y

https://www.nature.com/articles/s42255-025-01297-8

bitshiftfaced• 1 month ago

I don't know about smartness, but the Mediterranean diet might be one signal. It's comparably low protein and has strong evidence for longevity.

edelbitter• 2 months ago

all these data come from nonhuman lab animals

Though what I have see so far is far from everything that could be learned from these surprisingly-humanlike mammals. Still need more research on timing. Maybe protein metabolism is not that different from the better studied methods of derailing glucose metabolism. Maybe the damage is set and done after any prolonged phase of inappropriate diet, and later minor adjustments in consumption have very little additional effect, after controlling for weight and caloric intake.

Maybe all humans need to do is watch their protein intake until puberty.. and then only 60 years later, as failing to retain muscle strength becomes more likely to kill them than any detrimental effect of excessive protein intake.

scythe• 2 months ago

Think of the body like a car, suggests Clemence Blouet, a neuroendocrinologist at the University of Cambridge in the UK. You can drive fast, using lots of fuel and putting wear and tear on the auto. Or you can stick to a gentle 15 miles per hour, and the car lasts longer. Living in a high-protein or high-calorie fast lane, she muses, could lead to the accumulation of those pro-aging oxygen radicals. Protein, in particular, also turns on systems that promote growth as well as aging. Restricting the diet could mean fewer of those damaging radicals and less pro-aging actions, keeping the body in smoothly working order for longer.

The implications here for quality of life are pessimistic. Also, the "extension" in the study is about 10%, but driving responsibly can make your car last many times longer.

miltran• 2 months ago

Radicals, i think mostly caused by high carbohydrates, ie Advanced Glycation End Products (AGEs) which probably mainly are generated by overconsumotion of carbohydrates.

You can have a keto/carnivore diet which, will minimize AGEs, is the meat/protein actually bad for you? (Assuming you avoid the std diet carb overconsumption ofc)

notabee• 2 months ago

I think that fasting-mimicking diets are a way to potentially get some of these benefits through occasionally engaging these "slower speed" repair mechanisms without permanently living with bare minimum protein intake. But I also think that at this point so far we've seen fat, sugar, and then all carbohydrates villainized. I don't think that excessive protein is going to turn out to be a good idea either and it will likely also have its turn as villain, especially after all of these new high protein fad foods that are still highly processed junk run their course. People just need to balance their damn nutrients and eat whole foods. There aren't many real shortcuts to health, but we're just desperate to find them due to time poor societies obsessed with hyper-optimization.

storus• 2 months ago

So people are pushed to their limits at work, but a university neuroendocrinologist suggests living a relaxing life that would require blander diet. What a wonderful solution!

sublinear2• 2 months ago

Protein dominates the grocery shelves: Protein chips. Protein cookies. Protein water.

Yeah and most of it is incomplete plant protein missing amino acids.

Protein restriction, Phillips says, is a sort of “lite” version of a more well-known longevity hack — caloric restriction.

I'm confused by this since protein is much lower calorie than fat or carbs.

dahinds• 2 months ago

protein and carbohydrate are both 4 calories per gram?

sublinear2• 2 months ago

Protein serving size is generally lower than carbs in a typical meal. It's not that simple.

cavisne• 2 months ago

When you include the thermic effect of food protein is closer to 3 calories per gram. Ie it burns about a calorie to digest a gram of protein

kuerbel• 2 months ago

Yeah and most of it is incomplete plant protein missing amino acids.

Common misconception. Soybean, quinoa, buckwheat provide all essential amino acids in good proportions

almost all plant proteins contain all nine essential amino acids, just in lower proportions.

gblargg• 2 months ago

https://archive.is/c8Pep (avoid the popups)

paulpauper• 2 months ago

I don't think it matters much. People are not mice. The vast majority of people will not overconsume or under-consume protein. There is a huge range where people are eating enough protein.

fireflash38• 2 months ago

I imagine it goes over about as well as trying to get people to be more vegetarian.

Protein has become pretty tightly associated in culture with healthy.

odyssey7• 2 months ago

Maybe more so with fitness than with health. People generally think of Mediterranean diets as healthy but not as a looksmaxxing linchpin.

supertroop• 1 month ago

And with dude bro culture. It’s yet another wedge issue.

jonplackett• 2 months ago

Does this translate to humans though? At the least it should be tested with something living longer than a few years.

Mice have a very short window to reproduce compared to humans so n optimisation to live longer in absence of sufficient protein makes more sense.

We’re optimising quite different I would assume.

llm_nerd• 2 months ago

Aside from the normal disclaimer that studies in mice often aren't applicable to human, their low protein diet was a calorie reduced diet, and indeed the outcome of the LPHC group was statistically the same as the calorie-reduced diet.

In the LPHC they significantly bulked up the food with non-digestible cellulose, and the net effect was that they were basically testing calorie reduced diets twice.

We already know that a calorie deficit extends lifespan in mice, and I'm not sure what this adds.

"Protein dominates the grocery shelves"

This claim is insane. Like fully disconnected from reality.

Simple carbs and fats dominate grocery shelves. Yes, they try to upsell you on high protein alternatives as premium priced products, but about 80% of the space in a grocery store are flours / corns / oils / sugars mixed into thousands of different products.

m463• 2 months ago

We know calorie-restricted diets extend life. Are they saying that protein might be the underlying cause, or is their experiment just a hidden calorie-restricted diet?

vannevar• 2 months ago

I don't think that any study on the benefits of protein intake is meaingful if it does not also take into account exercise. The effect of a protein-only diet on a largely sedentary animal that lives in a small cage is likely to be very different than the effect on a human who exercises regularly.

Rastonbury• 1 month ago

not much point if u live to 90 but your muscles have atrophyed and u can barely move about

The curious case of low-protein diets

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