Image courtesy of Prevention

If the promise of a slimmer waistline hasn't curbed your sweet tooth, maybe the desire for smooth skin will. It's a bitter pill to swallow, but experts now believe that a lifetime of overeating sugar can make skin dull and wrinkled.

At blame is a natural process that's known as glycation, in which the sugar in your bloodstream attaches to proteins to form harmful new molecules called advanced glycation end products (or, appropriately, AGEs for short). The more sugar you eat, the more AGEs you develop. "As AGEs accumulate, they damage adjacent proteins in a domino-like fashion," explains Fredric Brandt, MD, a dermatologist in private practice in Miami and New York City and author of 10 Minutes 10 Years. Most vulnerable to damage: collagen and elastin, the protein fibers that keep skin firm and elastic. In fact, collagen is the most prevalent protein in the body. Once damaged, springy and resilient collagen and elastin become dry and brittle, leading to wrinkles and sagging. These aging effects start at about age 35 and increase rapidly after that, according to a study published in the British Journal of Dermatology.

Is Your Diet Sabotaging Your Skin?

Besides damaging collagen, a high-sugar diet also affects what type of collagen you have--another factor in how resistant skin is to wrinkling, says Brandt. The most abundant collagens in the skin are types I, II, and III, with type III being the most stable and longest lasting. Glycation transforms type III collagen into type I, which is more fragile. "When that happens, the skin looks and feels less supple," says Brandt. The final blow: AGEs deactivate your body's natural antioxidant enzymes, leaving you more vulnerable to sun damage--still the main cause of skin aging.

One group that knows all too well sugar's ravaging effects: people with diabetes, who--because they can suffer from years of undetected high blood sugar--often show early signs of skin aging. "Depending on how well their disease is controlled, diabetics can have up to 50 times the number of AGEs in their skin as those who don't have diabetes," says Karyn Grossman, MD, a dermatologist in New York City and Santa Monica, CA, and chief of the division of dermatology at St. John's Hospital in Santa Monica.

13 Sugar-Busting Dinners

The good news about sugar-damaged skin: It's never too late to turn back the clock. One way is to build new collagen with products that contain retinoids--look for retinol in OTC serums and lotions or prescription creams such as Renova, Avage, and Differin. To keep this new collagen supple, prevent AGEs from forming by taking steps to minimize the damage sugar causes to your skin.