MHC professor, alums and student study keto trade-offs
New research from Mount Holyoke College reveals that mimicking a keto diet in fruit flies extends lifespan but reduces fertility, suggesting that ketone bodies could act as metabolic signals rather than simply a fuel source.
Mount Holyoke College collaborated with the University of Connecticut to research the impacts of a ketogenic lifestyle. Co-authors include Christianna Smith Professor of Biological Sciences Craig Woodard and alums Meredith Becher ’23, Xinyue Shang ’25, Fangyi Coco Zhai ’22 and Tina Fortier ’95 as well as current student Yumeng Han ’27.
The results suggest that the benefits of a ketogenic lifestyle may have a significant biological trade-off. The results of this research were published in the November 2025 volume of Developmental Biology, and showed that mimicking a keto diet appears to extend lifespan in fruit flies while simultaneously reducing their fertility and slowing their physical development.
The study came about as University of Connecticut student Derek Lee observed that consuming ketone bodies — the fuel source the liver typically produces when the body is starving for sugar — seems to slow down the growth of fruit fly colonies. Soon afterwards, Zhai ’22 found that fruit flies on a diet supplemented with ketone bodies had higher levels of the active form of a protein involved in recycling old cell components into new ones.
Woodard and Geoffrey Tanner, an associate professor in residence at the University of Connecticut, had met when Tanner served as a visiting faculty member at Mount Holyoke. After discussing Zhai’s and Lee’s findings, they decided to study the influence of ketone bodies on the internal chemistry of fruit flies.
While traditional ketogenic diets are difficult to maintain because they require a strict high-fat, low-carbohydrate regimen, this study took a different approach. Rather than eliminating carbohydrates, the researchers added ketone bodies to a standard high-carbohydrate diet, allowing the team to determine whether the benefits of ketosis could be achieved through supplementation rather than extreme restriction.
The results revealed a clear shift in the flies’ biology. Female flies on the new diet laid approximately 14% fewer eggs than those on a standard diet, and the larvae developed more slowly, with fewer reaching adulthood. In earlier research, Tanner showed that ketone bodies extend lifespan in adult flies. Interestingly, the “fat bodies” in these flies (an organ similar to the human liver) showed increased activity of a protein responsible for recycling old cell components. This suggests that ketone bodies aren’t just a backup fuel source; they also act as signaling molecules to change metabolic behavior.
This discovery is promising, as it implies that individuals who rely on ketogenic diets to manage conditions such as epilepsy or diabetes might achieve similar results through a less restrictive regimen. By adding ketone bodies to a standard diet, patients might achieve the metabolic benefits without cutting out grains, vegetables, fruits and sweets. The research team plans to conduct further research to fully map the protein and metabolic changes caused by this supplemented diet.
