Over the years, more and more people in the country have reached morbid obesity, posing a serious threat to their health and becoming increasingly aware of the importance of weight loss. But losing weight is not an easy task, and many people end up choosing weight loss surgery to help them control their weight after trying a variety of conventional weight loss methods. However, there are some people who feel that weight loss surgery is similar to dieting to lose weight, so if they can control their diet, they can lose weight without weight loss surgery. But is this really the case? One of the weight loss principles of bariatric surgery is to modify the gastrointestinal tract to control the amount of diet the dieter eats, and some of the procedures also reduce their absorption efficiency to enhance the weight loss effect. In this respect, it does look somewhat similar to dieting for weight loss, but in fact, the weight loss principle of bariatric surgery is not the only one. The best phase for weight loss with bariatric surgery is actually the period of recovery after surgery. Within a few months after surgery, the dieter can only eat liquid or semi-liquid food to meet his or her nutritional needs because the body needs to recover, and most of the energy to maintain physical activity comes from fat, so that he or she can lose a lot of weight. And the so-called diet is only a single diet after the body recovery is restricted. But despite this, their overall daily intake is not very low, all to meet the basic needs of the body, the weight loss effect is very limited, which is why the weight loss period of bariatric surgery is basically within one year after surgery. Therefore, simple dieting can not achieve the purpose of weight loss like weight loss surgery, it is best to maintain exactly the same weight or low range of weight loss, to really get rid of obesity, or to use a variety of methods to work together to do so.