Auburn, April 25---As the saying goes, there are two things in life that are certain: death and taxes.

If you’re obese, sedentary or consume too much saturated fat, add to that list a greater likelihood of developing certain forms of cancer, especially breast and prostate cancer.

"We’re not quite sure how these components (obesity, sedentary lifestyle or high-fat diets) actually contribute to these cancers," says Dr. Robert Keith, an Alabama Cooperative Extension System nutritionist. "They’re all tied closely together."

"It’s hard sorting everything out, though it does seem certain excess body fat is a big contributor."

While many people traditionally have thought of body fat as just a storage place for energy, researchers have learned it involves more than that, Keith says. Fat tissue, in fact, appears to be a very active substance within the body.

"One of the things it can produce is a steroid-type hormone," Keith says. "It produces estrogen-like hormones, and if you have excess body fat, you tend to produce more of them."

Research has shown some forms of breast cancer as well as prostate cancer are sensitive to these hormones. Cells exposed to these hormones become more metabolically active and begin dividing at abnormally higher rates.

"We know this whole process is linked with body fat, but we’re not quite sure how," Keith says. "We’re not sure whether it stems from eating too much saturated fat or consuming too many calories."

Experts also suspect a link between body fat and colon cancer, though not in the same way as hormone-related cancer. Some researchers even suspect this particular cancer may stem from factors that are related to excessive body fat but that are different nonetheless.

"We know that people who exercise a lot have lower incidences of colon cancer – possibly because they tend to eliminate more often," Keith says. "Conversely, people who are obese tend to exercise the least and to eliminate less often."

Even so, Keith says, researchers have had a hard time isolating the root cause of colon cancer because obesity and exercise are so closely tied together.

"These two factors are hard to separate because obesity and low levels of physical activity are so closely linked," Keith says. "When someone gets colon cancer, is it because he was obese or because he didn’t exercise?"

Other obesity-related factors also may contribute to colon cancer, Keith says.

For example, people who eat high-fat foods, a major contributor to obesity, tend to secrete more bile in their intestines. Bile can be converted into a carcinogen after reaching the intestinal tract and is suspected by some to contribute to an increased colon-cancer risk.

Nevertheless, Keith says it’s important to remember that obesity and high-fat diets are only two of the risk factors associated with breast, prostate and colon cancer. Fit people who exercise regularly are not immune to these types of cancers, though they reduce their risk significantly by following healthy lifestyles.

What science finally determines to be the root cause(s) of cancer isn’t the biggest issue for consumers, Keith says. What is important is for consumers to understand the close link between three factors that contribute to breast, prostate and colon cancer: obesity, sedentary lifestyles and high-fat diets.

"I’m not sure what science will finally determine is the ultimate cause – or causes – of these types of cancer," he says. "This I do know: If you’re overweight, sedentary or consume too many high-fat foods, you face an increased risk of certain types of cancer."

"So the important thing, from the standpoint of consumers, is adopting a healthier lifestyle that will reduce these risks."