Many people know that obesity can cause many complications, but most people do not notice that obesity is also an important cause of many types of cancer, and is no less harmful than smoking. As early as 2015, the British Daily Mail published the views of Harvard University scholars on the impact of obesity on cancer, they believe that in the next 10 years, the number of patients with cancer caused by obesity in the United States and the United Kingdom will be higher than those with cancer caused by smoking, becoming the number one cancer-causing factor. Experts from the World Cancer Foundation also said that after years of observation and research, it was found that 33% of cancers occur in obese people, with obese women having a higher risk of malignant tumors than obese men. The relationship between obesity and cancer has always been of great concern to experts, and some people have summarized that the longest cancers suffered by obese people are esophageal cancer, pancreatic cancer, rectal cancer, uterine cancer, kidney cancer and breast cancer, and more than ten kinds of cancers, and have given a rough explanation to the reasons why obesity leads to cancer. Fat not only has the function of storing energy, but also affects the secretion of hormones in the body. Obese people have more fat, which makes the level of some hormones in the body relatively high, and it is because of these overproduction of hormones that the probability of cancer increases. For example, the increased secretion of estrogen due to excess fat will increase the risk of breast cancer in women; the increased secretion of growth hormone due to excess abdominal fat will also lead to an increase in the probability of many cancers. At the same time, obese people are also prone to hypertension, coronary heart disease, diabetes, sleep apnea syndrome and other diseases, which reduce the immunity and resistance of human body, lower the ability of cell self-repair, and also easily lead to genetic mutation of normal cells, thus inducing cancer. Nowadays, there are few studies on obesity and cancer, and we have basically reached a consensus that obesity is an important cause of cancer as well as smoking, in addition to the common complications, but the problem of obesity is getting more and more serious because the national people are not profound enough about the harm of obesity and the influence of social environment. A long way to go.