A large number of epidemiological studies suggest that obesity can affect the occurrence of certain cancers. The American Cancer Society has conducted 12-year follow-up observation on a large sample of 750,000 people, and the results show that the risk factors of certain cancers occurring in obese people have increased significantly, and the risk of endometrial, cervical, ovarian and breast cancers in obese women has been elevated, while the incidence of colon cancer and prostate pain in obese men has been increased. Moller et al. in Denmark found that after 11 years of follow-up study of 44,000 people, the likelihood of esophageal cancer, liver cancer and pancreatic cancer increased in obese people, and certain endocrine-related cancers, such as endometrial cancer, certain gastrointestinal tumors, renal cancer, in female obese people with increased RR. According to the tracking studies conducted by the World Health Organization (WHO) and the American Institute for Cancer Research (AICR), obesity, coupled with a lack of physical activity, not only contributes to cardiovascular disease, but is also the biggest cause of cancer formation. However, the general public is generally lack of vigilance for this association, a questionnaire survey conducted in the United States, pointed out that up to 75% of the public does not have this common sense. In fact, according to the World Health Organization, between 1/3 and 1/4 of global cancer cases are directly related to obesity. According to the study, in non-smoking adults, obesity is a major risk factor for colorectal, breast, prostate, esophageal, endometrial, and kidney cancers. In the United States alone, 500,000 people die each year from these cancers. Experts believe that adults who gain an average of 0.5 pounds or more per year have a much greater risk factor for cancer than the general population. Because weight gain and cancer are long-term cumulative symptoms, once the results are formed, it is not easy to return to normal or safe levels. Based on the theory that prevention is better than cure, it is important for the general public to control weight gain in adulthood. According to the survey results, adults who gained more than 22 pounds after the age of 20 had the highest chance of getting cancer among all the samples. The possible mechanisms by which obesity causes cancer are as follows: excess fat and the formation of obese cells promote the secretion of high levels of insulin and estrogen (estrogen, hormone), which accelerates the growth and division of cells, and at the same time increases the growth and formation of abnormal cell cancer cells. In addition, adipose tissue can effectively accumulate carcinogens, hindering their metabolism and discharge, which is the main cause of cancerous tumors. An oncologist once pointed out: “If the tumor is a growing plant, then fat is its growth hormone.”