I love sweet treats as much as the next person so it pains me to say this, but eating too much sugar causes wrinkles. Sugar triggers a natural process called glycation, which is the same chemical reaction that turns meat brown when you cook it. The sugars bind with tissues to form harmful molecules, called advanced glycation end products (ironically known as AGEs), which damage elastin and collagen -- two substances your skin needs to stay supple and elastic. AGEs also damage the kidneys, brain and other essential organs.
A 2007 study in the British Journal of Dermatology found that sugar's effects on the skin begin to show at about age 35 and become more pronounced as you get older. And it's not just the obvious culprits, like soda and candy, that cause damage; other foods with a high glycemic index, like white bread, pasta and potatoes also cause the formation of AGEs, because they are quickly converted to sugar in the bloodstream. To make matters worse, AGEs also make the skin more susceptible to sun damage, which in turn accelerates the glycation process.
It's hard to resist the lure of chips, cookies and french fries, but cutting down on sugary and starchy foods is the first step toward repairing AGE damage and preventing further glycation from occurring. The GI Database, maintained by the University of Sydney in Australia, is a handy tool that will help you determine the glycemic index of your food and includes many well-known brands and products. (Turn tonight's dinner into tomorrow's great skin.)
Finally, you can make up for lost collagen by using a prescription retinoid, like Retin-A, Differin or Tazorac. Retinoids are the only products proven to increase collagen production and diminish existing wrinkles. (Learn more: Six great reasons to use a retinoid.)