Watch Your Weight, Cut Your Cancer Risk

(CNN) -- The American Cancer Society said Thursday that keeping weight under
control is the most important thing you can do to prevent the disease.

In revised guidelines, the society put top priority on diet and fitness,
saying that eating a nutritious diet, staying active and limiting alcohol
are the top things American should do to fight cancer.

The guidelines are published Thursday in CA: A Cancer Journal for
Clinicians. (Watch how fitness can cut cancer risk -- 1:53 Video)

One-third of the more than 500,000 cancer deaths each year are attributable
to poor diet and no physical activity, the cancer society said. That's about
the same number of cancer cases caused by smoking.

Research has long shown that colon, rectal, stomach, breast , prostate and
pancreas cancers are related to diet. New studies indicate that for most
nonsmokers, weight control can cut other cancer risks.

"There is evidence that losing weight can reduce the risk for postmenopausal
breast cancer, and because of hormonal changes that occur with weight loss,
there's reason to believe it's beneficial for other cancers as well," said
Colleen Doyle, director of nutrition and physical activity at the American
Cancer Society and a co-author of the new guidelines.

The guidelines also say that the standard recommendation -- 30 minutes of
moderate exercise five days a week -- is still good, but it works better
with with more strenuous activities such as biking, running or power
walking.

Doyle said it's time people understand they have a say in the future of
their health. "Unfortunately, there's no guarantee. You can do all those
things and still get cancer. But the good news is that a lot of people think
they don't have any control over their risk of cancer and we're here to tell
people that absolutely you do have some control."