New research findings show that extra body fat doesn't just weigh you down. Scientists now have evidence that too many fat cells prompt ongoing reactions in the body that may increase cancer risk.

If the researchers at the Epidemiology Research department at Johns Hopkins University are right, excess fat may alter the body's basic functioning in ways that raise risk for cancer and other diseases.

Research has already shown that obesity boosts levels of hormones such as estrogen, for example, which increase risk for breast cancer in post-menopausal women. Too much body fat, especially in the abdomen, also increases insulin resistance, priming the body for diabetes.

Now, recent findings suggest that obesity, especially around the waist, may also influence the body's inflammatory response so that risk for colon cancer is higher.

Too Much of a Good Thing

Inflammation is the body's first response to infection or injury. It's essential to healing, but it can go awry. Many scientists suspect that chronic low-level inflammation of body tissues underlies a lot of disease processes. How does this happen?

Substances called cytokines are part of the body's inflammation response to help with fighting infection and healing wounds. Cytokines are made by white blood cells, but fat cells can make cytokines too.

In addition to fighting infection, cytokines help with wound repair by stimulating tissue growth. Research suggests that when the body has an oversupply of fat cells, those cells release too many cytokines. This boosts the body's inflammatory response and causes damage to cells and their DNA.

Where there is genetic damage plus stimulation for cells to grow, the chance of cells growing out of control and becoming cancer is increased.

A Link to Diabetes and Cancer

A previous study, funded in part by AICR showed that people who were obese (with a body mass index of 30 or higher) had a higher risk of colon cancer. People who were diabetic or had poor glucose control also had increased risk.

What's more, a follow-up study, , found that people who had elevated blood levels of C-reactive protein also had a higher risk of colon cancer. CRP is a marker for the presence of low-level inflammation somewhere in the body.

Some cancers are known to be associated with persistent inflammation that's related to chronic infection. For example, people infected with one of the viruses that cause hepatitis are more susceptible to liver cancer. Chronic infection with Helicobacter pylori, a bacterium that lives on the lining of the stomach, increases risk for stomach cancer. People with inflammatory bowel disease have above-average rates of colon cancer.

The idea that fat cells could be actively involved in promoting inflammation is a relatively new one. There is more to being fat than carrying around excess weight. People should begin thinking of excess body fat as actively harmful to their health.