Caloric restriction increases lifespan but affects brain integrity in lemurs

While most experiments done until now have investigated the effect of calorie restriction, there have also been some more specific experiments.

Some experiments have obtained similar lifespan extension by protein intake restriction, not by energy intake restriction. A few other experiments have obtained the same effect by restricting only the methionine intake.

Methionine is required for the initiation of the synthesis of any protein. When it is insufficient, the rate of protein synthesis slows down everywhere in the body.

Assuming that all these experimental results are correct and that they have a more general applicability than for the few tested animals, then it appears that the lifespan extension is achieved by slowing down the rate of protein synthesis.

This might work by preventing an unnecessary recycling of the body components, which eventually accumulates defects. Nevertheless, in the case of injuries or illness, a reduced rate of protein synthesis is very undesirable.

It is likely that in big or long-lived animals the rate of protein synthesis is already diminished and close to the minimum acceptable, because such animals have lower energy intake per mass needs (even when comparing poikilotherms).

This would explain why such lifespan extension methods do not seem to work in big animals. It is likely that they have low or no effect in humans too.

It's very difficult for elderly people to build and maintain lean muscle mass because the endocrine and digestive systems become less effective with age. After about age 70, progressive muscle loss is unavoidable (at least without heavy use of performance enhancing drugs which cause other negative side effects). So, if you want to live a long life without falling down the stairs and breaking a hip when you're 80 then you need to build up some extra muscle when you're young. That means eating a relatively high protein diet (but not a caloric surplus unless you're underweight).

> Some of our lives and jobs are much simpler than we realize.

Based on the output of deep learning models, most of our lives and jobs probably don't even require sentience.

When you say "mostly optional" I assume you mean working out will drastically reduce the rate of muscle loss. Is that what you mean or are there other intervention?

Eh, that seems to be only partially true. You are forever aware of the feeling of location loss, positional unawareness. You wake up every minute, in a strange city, strange place, with strange people. Normal reaction to that is stress and panic. Which is why you get medicated against fear and stress as dementia patient.

In this case I believe it's in (confusingly named) lemurs.

Not OP, but prolonged fasting is well understood to significantly affect the immune system.

I doubt not eating for a single day while fighting a cold is going to matter though, especially if sedentary/sick in bed.

During a prolonged fast you'll be decreasing white blood cells, which doesn't seem ideal if you're already sick. But AIUI it's mainly this aspect that "reboots the immune system", and can prevent illness once feeding has resumed and the catabolism undone. Basically you get a refreshed immune system, afterwards:

“When you starve, the system tries to save energy, and one of the things it can do to save energy is to recycle a lot of the immune cells that are not needed, especially those that may be damaged,” Longo said. “What we started noticing in both our human work and animal work is that the white blood cell count goes down with prolonged fasting. Then when you re-feed, the blood cells come back. So we started thinking, well, where does it come from?” [0]

[0] https://news.usc.edu/63669/fasting-triggers-stem-cell-regene...

There are some research on mice[0] with the ketogenic diet (usually you go in ketosis state if you are fasting).

[0] -- Ketogenic diet activates protective γδ T cell responses against influenza virus infection https://www.science.org/doi/abs/10.1126/sciimmunol.aav2026

Try it with biostatistics device both ways. You will see your resting heart rate is substantially lower when you stop eating early, and this will improve your HRV and deep sleep stats.