Not enough studies have been done but theoretically, the peel and pulp contain a soluble fiber called pectin which is said to help you feel satiated. This would allow you to feel fuller for longer and not feel the need to eat more than necessary.
Lemons generally have a lot of benefits. They may help with heart health, lowering blood pressure, decreasing inflammation, preventing kidney stones, lowering cholesterol, protecting against anemia and more. Plus, if you add lemon to your water, you’re likely to drink more because it’s flavored.