Most people do not associate obesity with cancer and are often surprised by the connection. Often by the time people are diagnosed with cancer they tend to be ill and thin, so the association with obesity is not made readily.

However, experts have now concluded that there is now ample evidence that obesity increases the risk of cancers of the breast (postmenopausal), endometrium (the lining of the uterus), colon, kidney, and esophagus.

Obesity rates across the world are increasing sharply due to poor diet and a sedentary lifestyle and health experts are concerned that the number of cancer patients are increasing because of the obesity "epidemic".

In 2002, about 41,000 new cases of cancer in the United States were estimated to be due to obesity. This means that about 3.2 percent of all new cancers are linked to obesity.

A recent report estimated that, in the United States, 14 percent of deaths from cancer in men and 20 percent of deaths in women were due to obesity. 

Preventing weight gain can reduce the risk of many cancers. It is recommended that people establish habits of healthy eating and physical activity early in life to prevent weight. There have been no clinical trials measuring cancer rates in people who have deliberately lost excess weight, however there are many observational studies that have noted that those who lost weight appear to have a reduced risk of cancer.

As with all things, prevention is better than cure.