Frustrated when you don't see results on the scale after weeks of walking or lifting weights? Don't let it throw you off your exercise schedule. Study after study shows you're fighting cancer even if you don't see a big drop in pounds.

"Even with stable weight, the increase in exercise will improve glucose metabolism, insulin levels will be lower and in fact cancer risk is lower," said Dr. Colditz.

How much lower? How about a 25 percent decrease in colon cancer and 20 to 25 percent for breast cancer. There are also clear links between physical activity and reduced risk of endometrial, lung, and prostate cancer.

"We're not saying you've got to become a marathon runner or a vegetarian you actually here in terms of exercise you actually increasing activity will lower risk of cancer," said Dr. Colditz.

It's as simple as following national guidelines for activity. At least 30 minutes of moderate activity five or more days of the week, or vigorous activity for at least 20 minutes on three or more days of the week.

"Ideally, 30 minutes a day. Actually if we get to more than 10 thousand steps a day we will get a substantial reduction in both diabetes and cancer," said Dr. Colditz.

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