With the development of society, people’s economy and living standards continue to improve, both children and adults, the incidence of overweight and obesity are constantly increasing. At present, many serious diseases caused by obesity, such as hyperlipidemia, hypertension, increased blood sugar, coronary heart disease and fatty liver, have attracted great attention, but the phenomenon that obesity can significantly increase the incidence of certain cancers has not yet attracted sufficient attention. According to the statistics of World Health Organization (WHO), obesity has become the second most important cancer-causing factor after smoking. A large number of studies have proved that total fat intake is closely related to cancer incidence and mortality rate, 35% of cancer cases and 70% of cancer deaths are closely related to nutritional status, and overweight and obesity are one of the important factors. Obese men are more likely to have prostate cancer, rectal cancer and colorectal cancer, and obese women are more likely to have uterine cancer, ovarian cancer, breast cancer and gallbladder cancer. British research institutions reported that obese children have a higher chance of developing pancreatic cancer, bladder cancer, lung cancer and oral cancer in the future. The most likely mechanisms are: 1. Fat cells can stimulate the secretion of insulin and insulin-like growth factor, which disrupts the balance between cell proliferation and apoptosis, leading to uncontrolled growth of certain types of cells and carcinogenesis; 2. Obesity can weaken the immune function of the human body and reduce the immunity of the body; 3. metabolites have a carcinogenic effect, stone bile acid can cause cancer in rats, and colon cancer patients have higher stone bile acid content, research has confirmed that stone bile acid may be related to the occurrence of colorectal cancer.