You can lose weight, but you can't lose weight The reason is that if you just drink soup, you will lose water, skeletal muscle, fat and so on. Although you have lost weight, this way of losing weight is unhealthy. Long-term persistence will cause many unpredictable complications, but this is not the point. The point is that once you return to your original food intake, you will gain weight immediately. This is because the previous unhealthy eating habits led to the reduction of human metabolic rate. When you resume your diet, you will lose weight.