Whenever I see people who are out-of-shape, I wonder whether they are uninformed or they just don't care. Even eighty- and ninety-year-olds should be able lift weights, cycle long distances and compete in athletic competitions. Yet most people are in pathetic shape and suffer the consequences.

An expert group appointed by the International Agency for Research on Cancer of the World Health Organization met in Lyon, France to evaluate the evidence for the role of weight control and physical activity in preventing cancer, and to identify priorities for research and for public health action in relation to the primary prevention of cancer. They concluded that limiting weight gain during adult life, thereby avoiding overweight and obesity, reduces the risk of postmenopausal breast cancer and cancers of the colon, endometrium, kidney (renal cell) and esophagus (adenocarcinoma). Limiting weight gain also possibly reduced risk of cancer of the thyroid.

The working group also concluded that there was sufficient evidence for the role of physical activity in preventing colon and breast cancers, and limited evidence for the cancers of the prostate and endometrium. Taken together, the working group concluded that excess body weight and physical inactivity account for approximately a quarter to one-third of cancers of the colon, breast, endometrium, kidney (renal cell) and esophagus (adenocarcinoma). Thus being fat and out of shape appear to be the most important avoidable causes of these cancers.

Weight loss among overweight or obese persons possibly reduces risks of these cancers, and we know that it reduces heart attacks, strokes and diabetes. If you have been gaining a few pounds each year, it's now time for you to start an exercise program and stop setting yourself up for cancer, heart attacks and diabetes.