Most college students don't think about aging much, but they do think about food and sex a lot. Little did you know that giving in to their two favorite preoccupations may accelerate the aging process. Feeding level and reproduction are both linked to aging, at least in most animals that have been studied.
Reducing feeding or reducing reproduction reliably increases lifespan in lab animals from worms to mice. The degree to which feeding must be reduced to extend lifespan (about 40 percent less than a full diet) almost always reduces the number of offspring produced. Because of this, biologists have long thought that there is just one way to slow aging, whether it is initiated by reducing feeding or by reducing reproduction. For college students preoccupied with food and sex, this might mean that both having your cake and eating it too may not be worse than indulging in only one of your preoccupations.
My lab uses grasshoppers to study the effects of diet and reproduction on lifespan. We use grasshoppers to address this fundamental question in biology because they are cheap, easy to use and can teach us things that apply to most animals. Using simple animals to study biological mechanisms is a tried-and-true approach that supports direct medical research. In female grasshoppers, lifespan is increased about 20 percent by either reduced feeding or reduced reproduction (via surgical removal of the ovaries). When females with their ovaries removed are given free access to food, they eat about 35 percent less than do those with intact ovaries. This amount is remarkably similar to the reduction in food needed to extend lifespan. So, both treatments reduce feeding and extend lifespan, and on the surface they appear to be extending lifespan in the same way. This provides hope for the idea that reduced reproduction and reduced feeding work the same way, and that having all the food and sex you want may not be any worse for you than having only one or the other.
Removal of the ovaries, however, results in a doubling of fat and protein storage, while reducing feeding does neither. What's more, females with their ovaries removed and offered limited food ate about 55 percent less than females with intact ovaries. These females with experimentally reduced feeding and reduced reproduction lived longer than females with only reduced feeding or reduced reproduction. This implies the underlying processes add up, and they don't work by the same mechanism; that is, there may be multiple ways to slow aging. And this means that reproducing shortens your life, eating a full diet shortens your life, and doing both is worse yet (at least if you're a grasshopper).
So maybe college students don't think about aging, but they think a lot about two things that will get them older faster. (I know in college I figured I could be a world-beater if I could just stop thinking about food and sex long enough to get some work done.) But never fear, as the community of biologists that study aging, we're working hard on figuring out how they work, so people can enjoy both of their favorites without taking years off their lives.
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