“It’s not enough to say there’s an association between obesity and cancer. We need to know why,” Hudis says. “With the why, we can do something about it.”
Scientists are exploring several hypotheses on how excess fat increases a person’s risk for cancer. The answer may be slightly different for each type of cancer, but the encompassing explanation seems to be that obesity triggers changes in how the body operates, which can cause harmful cell growth and cell division.
Many of these changes may be linked to inflammation. In general, inflammation occurs when your body is reacting to something out of the norm — say a virus or a splinter in your foot. Obesity seems to cause chronic inflammation, which in turn may promote cancer development.
Take for example, Hudis says, hormone-sensitive breast cancers. Chemicals in the body meant to regulate inflammation also increase production of the hormone estrogen. And studies have shown excess estrogen can cause breast cancer tumors.