A recent study by researchers at the University of Connecticut has unveiled a fascinating discovery: old, obese fruit flies can become healthier and live longer by adopting a low-calorie diet.
If these findings hold for humans, it suggests it’s never too late for obese individuals to improve their health through dietary changes.
For many of us, as we age, overeating and obesity tend to go hand in hand. Obesity is generally defined as having an excess of body fat and is linked to various metabolic-related diseases, including heart disease and diabetes.
Numerous animal studies have demonstrated that reducing calorie intake, without causing malnutrition, can lead to a longer lifespan.
While human trials have shown positive effects of calorie restriction on health, especially in healthy obese individuals, the impact on lifespan has been challenging to study in humans.
In this study, researchers from the UConn School of Medicine focused on fruit flies. They fed these flies a diet high in sugar, protein, and calories, closely mimicking the processed modern diet associated with obesity.
The metabolic changes observed in these obese fruit flies were similar to those in obese humans. Remarkably, even when these obese flies were switched to a low-calorie diet later in life, their metabolisms underwent significant changes, increasing their lifespans.
Fruit flies typically have short lifespans, especially when raised on high-calorie diets (less than 80 days), but those on low-calorie diets can live considerably longer (up to 120 days).
The researchers raised multiple batches of fruit flies to investigate whether dietary changes in old age could impact a fly’s lifespan.
Some were raised on a low-calorie diet, providing only half the energy of a regular diet, while others were fed a high-calorie diet, supplying three times the usual calorie intake.
The study primarily focused on male flies. Surprisingly, young flies that switched from a high-calorie to a low-calorie diet at 20 days of age experienced significantly longer lifespans, similar to those raised on a low-calorie diet from day one.
What astonished the researchers even more was that the positive effects of switching to a low-calorie diet extended to older flies already in poor health.
Older flies raised on high-calorie diets had higher lipid levels in their bodies and expended more energy defending against reactive oxygen species, leading to a higher death rate.
However, when the surviving older flies switched to a low-calorie diet at 50 or even 60 days (when many had already passed away), their metabolisms transformed, their death rates dropped, and their lifespans increased.
Lead researcher Blanka Rogina pointed out that this study involved flies on high-calorie diets, similar to obese individuals. This suggests that shifting to a low-calorie diet later in life might have significant health benefits for obese humans as well.
The team also analyzed the genes expressed by high-calorie diet flies and compared them to those on a low-calorie diet. They found differences in genes controlling physiological and metabolic adaptation between the two groups.
Brent Graveley, Chair of Genetics and Genome Sciences at UConn School of Medicine, emphasized the remarkable finding that flies, even after spending a significant portion of their lives on a high-calorie diet, can experience lifespan extension by simply switching to a low-calorie diet.
Since many fundamental metabolic pathways in fruit flies are shared with humans, this study suggests that human metabolism might respond similarly. This implies that individuals following high-calorie diets could benefit from reducing calorie intake, even in old age.
The researchers are currently investigating whether there are any gender-related differences in the response to dietary changes by analyzing data from female fruit flies.
If you care about wellness, please read studies about how ultra-processed foods and red meat influence your longevity, and why seafood may boost healthy aging.
For more wellness information, please see recent studies that olive oil may help you live longer, and vitamin D could help lower the risk of autoimmune diseases.
The research findings can be found in PNAS.
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