Insulin is commonly used to treat diabetes, and it promotes the conversion of sugar in the body into fat, and does not have the effect of helping to lose weight, but instead may have the side effect of obesity. Therefore, insulin is not for weight loss. The main role of insulin is to regulate the body’s glucose metabolism, lowering blood sugar by promoting the uptake of blood glucose by skeletal muscle and adipose tissue. Insulin inhibits lipolysis and protein hydrolysis and promotes protein synthesis, which has the effect of increasing body weight and does not have a weight loss effect. If there is a need to lose weight, it is recommended to control from diet and exercise first. Eat less high oil and high salt food in daily life, and control the overall calorie intake. There is also proper physical exercise to create a calorie gap in order to achieve weight loss. One should not blindly lose weight through medication to avoid adverse consequences. Obese patients can consult a medical professional for weight loss.