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depends largely on menopausal status. Interestingly, before menopause obese women have a lower risk of developing breast cancer than women of healthy weight. However, after menopause, obese women jump to twice the risk. Estrogen seems to be the culprit. Before menopause, the ovaries are the primary source of estrogen, but fatty tissue also produces it. After menopause, when ovaries stop producing this hormone, fatty tissue becomes the main estrogen source. Consequently, estrogen levels in post- menopausal, heavy women can be twice as high as that of their lean counter- parts. High estrogen levels after menopause seem to play an important role in the development of breast cancer, but again, researchers don’t know why.

Colon (Colorectal) Cancer Although men can develop breast cancer, the rates are obviously many times higher in women. But colon cancer (which can also develop in women) occurs at much higher rates in men. The colon is commonly referred to as the large intestine, and men with a BMI

over 25 have an increased risk of developing cancer in this organ. Study after study consistently reports such findings, but like so much of what we’ve dis- cussed so far, the medical community still can’t say precisely why. Researchers have proposed a number of ideas concerning obesity’s effect on colon-cancer risk. One major theory suggests that high levels of insulin in obese people may promote the growth of tumors. Another theory con- cerns diet. A diet low in fiber has also been linked to an increased risk of colon cancer. Fiber is most plentiful in certain vegetables, fruits, legumes, and whole grains. All of these foods also tend to be extremely healthy and low in fat. Many people develop overweight and obesity at least in part because of unhealthy diets. If the unhealthy diet that contributed to the weight gain was also low in fiber (as most unhealthy diets are), could this be

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