Flies on a diet live much longer than flies that are allowed to eat all they want. But just a small whiff of extra food is enough to shorten the lives of the dieting flies again, a new study shows.

The effect only occurred in flies on restricted rations, though. When flies could eat their fill—and thus already had shortened lives—smelling more food didn’t cut their lives any further.

Mutant flies with damaged sniffers lived longer regardless of their diet and also escaped the ill effects of smelling food.

[Read](http://news.nationalgeographic.com/news/2007/02/070201-fly-smelling.html?source=rss “Read the Story”)(National Geographic)