That's Fit

Think you can cut just 300 to 500 calories a day from your diet? If so, it could be the very thing that keeps you living longer.

It's been said before: Limiting caloric intake can slow the aging process. This theory, based on the study of rats and mice, goes like this: Fewer daily calories decrease production of the thyroid hormone triiodothyronine (T3), which then slows metabolism and tissue aging. Now, a new study adds to this theory and shows that this hormone decrease occurs when humans regularly skip rich desserts or forgo the Big Mac for a turkey sandwich instead.

So, researchers know now that calorie restriction does indeed slow hormone production in both animals and humans. Great news. What they need to determine now is whether the restriction actually slows the aging process. Common sense says that it does -- there's lots of evidence that cutting back on calories can limit risk for many common diseases, like cancer, diabetes, and heart disease. Avoid these diseases, and yes, you will live longer.

One warning: If you do choose to cut calories, you still must maintain a healthy diet by eating nutrient-rich foods. Cut out the healthy stuff and you'll experience long-term slowing of the metabolism -- and this can make you fat. Oh, and don't forget the exercise.

Check out this AOL Health resource for more on longevity.