Fruit flies induced to become hungry end up living longer even when they eat a lot of calories.
The results of a recent study by researchers at the University of Michigan in the United States suggest that the perception of insatiable hunger alone may trigger the anti-aging effects of intermittent fasting. The animal does not need to starve.
“We sort of divorced [the life extending effects of diet restriction] of all the nutritional manipulations of the diet that researchers have worked on for many years to say are not necessary,” said physiologist Scott Pletcher.
“The perception of a lack of food is enough.”
Intermittent fasting has become a popular dietary fad in recent years, although at this point there is evidence supporting its benefits is limited And largely based on animal studies.
Work on fruit flies (Drosophila melanogaster) and rodents seems to suggest calorie restriction can extend lifespan and promote good health. But this is still just the beginning, and much more research is needed before the results can be extended to humans – eespecially since some studies have produced contradictory results, even highlighting potential dangers.
To further investigate the molecular mechanisms of fasting, the researchers behind this latest investigation once again turned to the humble fruit fly.
In the past, fruit fly studies have helped scientists identify many neural signals for hunger and satiety in the brain. These creatures split 75 percent of the same disease-related genes as us, and their metabolisms and brains bear useful similarities to those of mammals.
Branched-chain amino acids (BCAAs) are essential nutrients that appear to trigger feelings of fullness in flies when consumed. Eating more BCAAs therefore reduces their feeling of hunger.
To explore how this might impact aging, the researchers kept the fruit flies hungry by feeding them snacks low in BCAAs.
Their hunger was measured by how much food the insects consumed from a food buffet a few hours after consuming the snack.
Flies that were fed a low BCAA snack ate more food at the last buffet. They also targeted protein-rich foods rather than carbohydrate-rich foods — a sign that the flies were driven by need-based hunger, not craving.
So the researchers went straight to the source. When the team directly activated fruit fly neurons that trigger hunger responses, they found that these hunger-stimulated flies also lived longer.
“So”, Pletcher and colleagues to write“the motivational state of hunger itself, rather than the availability or energy characteristics of food, may slow aging.”
Other experiments showed that reducing BCAAs in flies’ diets also caused their hunger neurons to fashion modified support proteins called histones, which bind to DNA and help regulate gene activity. . Researchers believe these modified histones may be the link between diet, hunger responses and aging. Interesting way, previous studies have linked an increasing supply of histones to an extended lifespan.
Based on the results, the researchers believe chronic hunger could be an adaptive response, “mediated by histone protein modifications in discrete neural circuits, which slow aging.”
The findings could help explain why low BCAA diets seems to be good for our own health. Perhaps they supply the body with enough nutrients, without completely quelling the hunger signals in the brain.
Of course, this idea needs a lot more testing. A fruit fly study will not suffice.
So far, researchers are interested in determining whether the health of fruit flies is related to eating for pleasure as well as out of necessity.
The study was published in Science.