evidence: Cancer is the result of mutations that lead to uncontrolled cell growth and proliferation. The International Agency for Research on Cancer recognizes obesity as a cause of at least 13 different cancers. Obesity, defined as excessive fat accumulation that poses a health risk, is generally caused by eating more calories than one expends. People who consume a high-fat, high-sugar diet are thus prone to becoming obese, which could increase their risk of developing cancer.