Hunger prolongs life | Science and life

We often hear that hunger – or rather, moderation in food – slows down aging and prolongs life. There is a ton of research on exactly how fast diets work: they suppress background inflammation, stimulate cellular autophagy to rid cells of unnecessary junk, increase the accuracy of gene reading, and so on and so forth.

But in an article in Science employees University of Michigan It’s not about hunger, it’s about feeling hungry. What does hunger tell us? About the fact that tissues and organs do not have enough energy, and also about the lack of certain substances – they do not go into the energy furnace, but are needed in certain cellular processes. Thus, it is known that in animals and insects, the feeling of hunger occurs when there is a lack of amino acids leucine, isoleucine and valine (due to the general features of the chemical structure, they are called amino acids with branched side chains or amino acids with a branching chain). Animals and insects that lack leucine, isoleucine and valine tend to eat more proteins; at the same time, the lack of only three branched-chain amino acids prolongs life – we wrote about this two years ago.

The researchers experimented with fruit flies that were kept on a diet with varying levels of leucine, isoleucine, and valine. There were no calorie restrictions. Flies that were on a diet low in BCAAs ate even more calories than flies on a diet high in BCAAs. That is, the former constantly experienced more hunger than the latter, ate more than the latter, and at the same time they still lived longer.

But then, in different flies, they began to artificially stimulate those neurons that were associated with the feeling of hunger and which worked more actively on a low-amino acid diet. Flies, naturally, began to eat more, and regardless of the diet. However, they also live longer. That is, the stimulation of “hungry neurons” alone, the feeling of hunger alone, was enough to prolong life. From this we can conclude that the lack of branched-chain amino acids affects not so much the metabolism as the “hungry neurons”, and these neurons already affect the metabolism and other things that affect aging and life expectancy.

The researchers were able to find out that low levels of leucine, isoleucine and valine affect the chemical modifications of histone proteins. Histones serve as DNA packers, and depending on how they pack a particular piece of DNA, the information on it will be available or not available for reading. Chemical modification of histones is one of the ways of epigenetic regulation of gene activity. Modifications on them may look different depending on the circumstances. In one case, the pattern of modifications corresponds to the desire to eat more food, but life expectancy does not increase. And in another case, as it happens with a shortage of branched-chain amino acids, the pattern of modifications on histones is different, and the flies not only eat a lot, but also live longer.

In general, how exactly the epigenetic regulation of genes in “hungry neurons” is related to lifespan remains to be seen. So far, we see that the feeling of hunger itself can be very useful, regardless of the calories eaten (although, of course, calories also play a role, only in a different way – from the side of metabolism). As far as the “fly” results can be extended to humans, it will become clear over time, after all, our eating habits and food centers in the brain are arranged differently than those of Drosophila.