Obesity is affected by genetic and environmental factors, so obesity genes may be inherited, but dietary habits also play a big role. Obesity has family aggregation, and a variety of genes, there is a theory that when the body has a thrifty gene, the body if there is a shortage of food, the body will effectively utilize the food, when the food is abundant, it can cause abdominal obesity, this gene includes β3 adrenergic receptors, hormone-sensitive lipase, and so on. Environmental factors also play a big role in obesity, when the family diet structure is more fat, and love to eat sugary food, it is easy to appear family obesity. In addition if the fetus in the mother’s body malnutrition or low birth weight, it is easy to be obese in adulthood. However, the main cause of obesity is still excessive dietary intake, leading to excessive accumulation of fat. Therefore, obesity may be hereditary, but not necessarily all will be obese, but also with diet, lifestyle habits and so on.