Summary: New research indicates that the sensation of hunger itself can slow aging. Scientists found that fruit flies driven to feel hungry—either by altering diet or by stimulating specific hunger-related neurons—lived longer. The team also showed that hunger triggers changes in the brain’s epigenome that alter gene expression, feeding behavior, and lifespan.
Although the researchers caution against directly applying these results to people, they say the underlying mechanisms are likely conserved and could influence hunger drives in other species.
Key Facts:
- Feeling hungry, independent of reduced caloric intake, may contribute to slower aging, according to a study by University of Michigan researchers.
- Flies rendered hungry—either by reducing specific dietary amino acids or by activating hunger-promoting neurons—showed extended life span despite eating more overall.
- Hunger-induced changes in neuronal histone marks and the epigenome were linked to altered gene expression, feeding choices, and longevity.
Source: University of Michigan
Overview
Amid the many approaches people pursue for weight loss—from low-carb diets and intermittent fasting to surgery and medications—scientists continue to investigate how eating patterns influence health and aging. It has long been appreciated that limiting food intake can promote healthy aging across a variety of species, including some evidence in humans. This new study from the University of Michigan shifts the focus from the quantity and composition of food itself to the internal experience of hunger as a driver of lifespan effects.
Previous work had shown that even sensory cues—like the smell or taste of food—can negate the life-extending benefits of dietary restriction. Motivated by those observations, lead author Kristy Weaver, Ph.D., and principal investigator Scott Pletcher, Ph.D., and their team asked whether neural changes that drive food-seeking behavior might underlie the longevity benefits typically attributed to reduced intake.
To separate the subjective state of hunger from simple changes in diet composition or calories, the researchers used two complementary approaches in Drosophila (fruit flies). First, they modified the levels of branched-chain amino acids (BCAAs) in a small test food and later allowed the flies to choose freely from a buffet of yeast- and sugar-based options. Flies previously given a low-BCAA snack showed a stronger preference for yeast over sugar—behavior consistent with a need-based hunger signal—and, when maintained on a low-BCAA diet throughout life, they lived significantly longer than flies fed a high-BCAA diet. Notably, the low-BCAA flies actually consumed more calories overall, indicating that longevity was not due to reduced total intake.
In a second experiment designed to provoke hunger without changing diet, the team used optogenetics to stimulate neurons known to promote feeding. Flies exposed intermittently to red light that activated these hunger-associated neurons showed markedly increased food consumption—and yet they also lived longer than control flies that did not receive the neural stimulation. “We think we’ve created a type of insatiable hunger in flies,” said Weaver. “And by doing so, the flies lived longer.”
At the molecular level, the researchers mapped how hunger alters the neuronal epigenome. Limiting BCAAs and artificially activating hunger-promoting neurons were each associated with changes in histone modifications in the relevant brain cells. Those epigenetic changes affected expression of specific genes that feed back on feeding behavior and on physiological pathways tied to aging. The team linked acute hunger responses to the histone variant H3.3, while prolonged hunger appeared to reset the animals’ hunger set point in a way that delivered long-term benefits for lifespan.
Taken together, these experiments demonstrate that motivational states such as hunger can be sufficient to influence aging trajectories. The authors emphasize that while the results come from fruit flies, the mechanisms they uncovered—neural circuits interacting with epigenetic regulation—are broadly conserved and merit further study in other organisms.
Future work from this group will explore how hedonic eating—the drive to eat for pleasure rather than for physiological need—interacts with the neural and epigenetic pathways identified here, and whether those interactions also affect lifespan.
About this aging research news
Author: Kelly Malcom
Source: University of Michigan
Contact: Kelly Malcom – University of Michigan
Image credit: Neuroscience News
Original Research: Closed access. “Effects of hunger on neuronal histone modifications slow aging in Drosophila” by Kristy Weaver et al., published in Science.
Abstract (concise summary)
Hunger is a conserved motivational drive, but how it shapes physiology and aging at a molecular level remains poorly understood. This study shows that inducing a hunger state—either by limiting branched-chain amino acids or by activating hunger-promoting neurons—extends lifespan in Drosophila despite increased feeding. BCAA limitation altered neuronal histone acetylation, and preventing those epigenetic changes blocked both the increased feeding and the life span extension. Acute hunger increased feeding through the histone variant H3.3, while prolonged hunger appeared to lower a hunger set point and produce beneficial effects on aging. These findings indicate that internal motivational states alone can be determinative drivers of longevity.