Among the factors that are effective in causing obesity are: 1. Hereditary and genetic backgrounds such that the children of obese parents will become obese up to 80% in the future, followed by type 2 diabetes. 2. Our metabolism is closely controlled by several hormones. One of them is Ghrelin hormone, which is secreted from the upper part of the stomach (fundus) and causes uncontrollable intense desire and insatiable hunger. In normal people, the secretion of this hormone after filling the stomach (reported to 
the brain through the gastric vagus nerve) is inhibited by the brain and the person feels full. This mechanism is impaired in people with obesity for hereditary and genetic reasons, and despite the fullness of the stomach, the person does not feel full and this powerful hormone continues to be secreted excessively, so the person regularly eats more than the required capacity. The same issue causes the stomach to become larger and wider and increases its volume, and as a result, the secretion of hormones increases, which in turn causes a person to become more and more obese by creating a vicious cycle.  
3. What has been proven in various scientific studies is that the vast majority of obese people suffer from fast food(ing) or eating fast, and these people eat more and faster in case of neurological disorders. Changing eating habits is one of the mainstays of obesity treatment.  
4. Other factors that affect the occurrence of obesity is lifestyle. Today, with the increasing mechanization and sedentary life, the prevalence of obesity and type 2 diabetes almost triples every year, so that it is predicted that by the year 2030 more than 70% of Iranians will be obese and more than 52% of Iranians will have diabetes And we are actually facing a storm of obesity and diabetes.  
5. Today, with the prevalence of high-calorie and low-fiber foods such as fast foods and the use of fertilizers and chemical and hormonal toxins and excessive consumption of highly fattening starches such as rice, obesity has become more prevalent. 6. Some diseases such as hypothyroidism and some drugs such as corticosteroids cause obesity, especially in the central areas of the body.