So how do we boost or even hang on to our youth hormones? One way is to skip the cherry cheese Danish and enjoy the cherries straight. That's good advice for all the obvious reasons, but for a not so obvious one as well: Sugary pastries like that cherry cheese Danish have what is known as a high glycemic index. The glycemic index measures how quickly a food raises our blood sugar levels after we eat it and how quickly our levels return to normal.

Foods with a low glycemic index, like cherries, along with most fruits and vegetables and whole grains, encourage youthful levels of hGH and IGF 1, according to Dr. Giampapa.

They travel slowly through our digestive tems, so sugar enters our bloodstreams a little at a time, says Shari Lieberman, Ph.D., a nutrition scientist and exercise physiologist in New York City. This slow, steady rise in blood sugar promotes a stable release of insulin, the hormone that moves energy (glucose) from our blood to our cells.

When our insulin levels stay steady, our bodies produce less cortisol, often called the stress hormone, says Dr. Giampapa. That's good. Low cortisol levels encourage our bodies to produce DHEA as well as the hormones made from it.

By contrast, we digest highglycemic foods, such as cornflakes, rice cakes, white potatoes, and white rice, more quickly. As a result, our blood sugar rises rapidly, triggering a flood of cortisol. High insulin and cortisol levels reduce our output of DHEA and the hormones made from it.

We can discourage these youthstealing spikes in insulin and cortisol. by eating mostly foods with a low to medium glycemic index, says Dr. Giampapa.