The primary cause of simple obesity, where the reason for being overweight is unclear, is an energy intake that exceeds energy expenditure. There are also certain genetic factors involved. Generally, it is believed that susceptibility to obesity varies among human races, along with the presence of obesity genes and variations in genes related to obesity. Additionally, an individual’s metabolic type, appetite, digestive absorption functions, sleep quality, and metabolic efficiency form the basis for the development of simple obesity. Poor lifestyle habits, such as insufficient physical activity and excessive energy intake, are necessary conditions for its occurrence. Epidemiological surveys have shown that most people with simple obesity have a familial tendency towards the condition. Children born to obese parents are 5-8 times more likely to develop simple obesity than those born to parents who both have a normal weight. However, the majority of cases of simple obesity are not caused by obesity genes or mutations in genes related to obesity.