Of course, because you lose weight too fast, your skin has lost its elasticity. Just like a balloon deflates after it is blown up for a long time, there will be obvious relaxation. If it's not too serious, you can try some external firming cream, such as Clarins, which will be more useful and safer. Drugs are not recommended, because expensive drugs may also cause harm to the body, and at present I have not heard of any drugs that can help skin tissue shrink.