By Kathy LaTour & Melissa Weber

It isn’t news to anyone that being fat isn’t good for your health, but new studies point to some startling connections between obesity and cancer.

In the August 2004 issue of Nature Reviews Cancer, researchers found that obesity is linked to at least nine types of cancer: colon, breast (in postmenopausal women), endometrial, kidney, esophageal, gastric, pancreatic, gallbladder and liver. More specifically, obese men are twice as likely to develop colorectal cancer compared to normal-weight men. And obesity has consistently proven to increase breast cancer risk by 30 to 50 percent in postmenopausal women.

More startling is that in 2000, almost two-thirds of adults in the United States were overweight or obese. And a 2003 study estimates 15 to 20 percent of all cancer deaths in the United States are linked to overweight and obesity.

Another study published in The New England Journal of Medicine in spring 2004 reported the findings of American Cancer Society researchers, who followed 900,000 men and women for 16 years to study the relationship between obesity and cancer. Their findings showed that death rates from all cancers combined were 52 percent higher in obese men than in normal-weight men. For women, the rates were 62 percent higher.

In breast cancer, the risks are compounded because obesity not only increases a woman’s risk of developing the disease, but very obese women are three times as likely to die from the disease as thin women. One explanation is that fat cells produce estrogen in postmenopausal women, and a large number of breast cancers are linked to this hormone (see Treating Breast Cancer: The Duality of Estrogen).

The exact mechanisms for the connection between obesity and cancer have yet to be understood since they can vary for each cancer. But it is known that in addition to hormones, such as estrogen, insulin levels are increased in obese people. The location of fat for both men and women can also impact cancer risk, with studies indicating that fat in the midsection increases risk for prostate and breast cancers.

While no controlled clinical trial has been conducted to determine if avoiding weight gain will decrease the risk of cancer, observational studies have shown that avoiding weight gain lowers cancer risk. Exercise, a key component of weight control, has been linked to lower colon cancer risk for both obese and lean people. A healthy diet is also crucial in controlling weight.

What we also know about fat is that it’s more complicated for some than for others because genetics play a large role. That said, there are a number of logical, easy ways to be healthier. And what this takes is determination and changes in lifestyle.

The Centers for Disease Control and Prevention reported in March 2004 that obesity is quickly overtaking smoking as the country’s No. 1 cause of preventable death, claiming an estimated 400,000 lives in 2000. In response to the report, Health and Human Services Secretary Tommy G. Thompson announced a new national campaign called Calories Count to fight obesity, as well as a new obesity research strategy at the National Institutes of Health.

“This new report highlights FDA’s overall strategy for getting consumers accurate, helpful information that allows them to make wise food choices at home, at supermarkets and in restaurants,” said Secretary Thompson in a news release. “Taking small steps to eat a more balanced diet and to stay physically active can go a long way to reversing the epidemic of obesity that harms far too many Americans.”