It is a biguanide hypoglycemic agent. Directly acts on the metabolic process of sugar, promotes anaerobic glycolysis of sugar, and increases the uptake and utilization of glucose by peripheral tissues such as muscle and fat. At the same time, it inhibits intestinal absorption of glucose, inhibits hepatic glycogen dysplasia and reduces hepatic glucose output. Therefore, there are two principles for metformin to lose weight. On the one hand, it reduces sugar absorption by changing sugar metabolism, on the other hand, it reduces appetite by balancing insulin release.

However, it should be noted that the main cause of obesity is the accumulation of fat tissue in the body, which leads to the imbalance between fat and muscle tissue, excessive body fat and weight gain. Metformin itself can not reduce the accumulation of adipose tissue in the body, it only increases the anaerobic metabolism of glucose in muscle and reduces the energy supply of glucose to muscle tissue. Therefore, although the weight has decreased after taking metformin, users sometimes feel muscle weakness and fatigue. In practical application, in order to achieve the ideal weight loss effect, large doses of metformin must be taken, so the side effects of the drug are particularly prominent, and most users will have digestive tract reactions such as diarrhea, nausea, vomiting, abdominal distension, and oral odor. Long-term use is also easy to cause lactic acid accumulation, which may lead to lactic acid poisoning, nausea, vomiting, chest tightness and shortness of breath. In addition, it may also affect the absorption of water-soluble vitamins, such as vitamin B 12, folic acid, etc., which can cause anemia, capillary and peripheral nerve damage, and also have a certain impact on the absorption of trace elements calcium and phosphorus. Therefore, metformin is very effective in treating patients with type 2 diabetes who can't be well controlled by diet and exercise alone, but it is not suitable for normal people to take it as a weight loss health care drug.