Flies with a history of eating a high-sugar diet live short lives, even after they ease off the sugar. Recent research suggests that the sugar actually reprograms the insects’ gene expression, causing long-term effects on longevity.

The study, published in the journal Cell Reports, discovered that a sugar-laden diet early in flies’ lives stops the action of a gene called FOXO. The FOXO gene is important for longevity in a wide variety of species, including yeast, flies, worm and humans, so the researchers say the finding may have broad implications, according to a release about the study from University College, London. UCL scientists led the study.

"Dietary history has a long lasting effect on health, and now we know a mechanism behind this. We think the reprogramming of the flies' genes caused by the high-sugar diet might occur in other animals. We don't know that it happens in humans, but the signs suggest that it could," first author, Adam Dobson, PhD, UCL Institute of Healthy Ageing, said in the release.

The researchers compared the lifespans of female flies fed a healthy diet containing five percent sugar to those given eight times this amount—about the equivalent of humans eating only cake for 20 years. The flies, which live to about 90 days on average, were fed both diets for three weeks before all were given a healthy diet.

Even while eating a healthy diet, the flies that had previously eaten a high-sugar diet began to die earlier, and on average had seven percent shorter lifespans. The researchers believe this was driven by the sugar-rich diet eaten in early adulthood, which caused a change in the programming of the flies’ physiology.

In further experiments, the same thing happened to a species of worm. "The fact that transient high sugar accelerates ageing in both species and by the same mechanism is pretty shocking,” the study’s co-author, David Gems, a professor at the UCL Institute of Healthy Ageing, said in the release. “It is yet more evidence of how much we have to fear from excess sugar in the diet."