Scientists at the University of Michigan have found that the feeling of hunger itself can cause the rejuvenating effect of fasting without the animal needing to cut calories. The research was published in the journal Science.
Previous experiments on fruit flies (Drosophila melanogaster) and rodents have shown that calorie restriction can extend lifespan and improve health. However, more research is needed before results can be generalized to humans, particularly as some experiments produce inconsistent results and even reveal potential hazards.
In a new study, scientists have found that simply feeling hungry may be enough to slow the aging process.
Branched-chain amino acids (BCAAs) are known to be essential nutrients that have been shown to cause satiety in flies. Therefore, eating less BCAAs can increase hunger. In the experiment, the scientists first fed the hungry flies low-BCAA snacks, and after a few hours they were given access to normal food. Flies given a low-BCAA snack ate more food and also preferred high-protein foods over high-carb foods; this is a sign that flies are driven by hunger rather than desire.
At the same time, the same changes were observed in flies as when the calorie content of the diet was restricted. What’s more, the scientists found that these hunger-stimulated flies also lived longer when they directly activated the fruit fly neurons that triggered the hunger response.
“Therefore, hunger itself, not the availability or energy properties of the diet, can slow aging,” the scientists concluded.
The findings may help explain why low-BCAA diets are good for our health. They can provide adequate nutrients to the body without completely suppressing hunger signals in the brain.
Of course, this idea needs much more testing, including in humans. Although fruit flies and humans share 75% of the genes associated with human disease, medical application of the scientists’ results is only possible after testing them on mammals and humans.