What causes a weight-loss plateau?

During the first few weeks of losing weight, a rapid drop is typical. In part, this is because when you initially cut calories, the body gets needed energy by releasing its stores of glycogen. Glycogen is a type of carbohydrate found in the muscles and the liver.

Glycogen is partly made of water. So when glycogen is burned for energy, it releases water, resulting in weight loss that's mostly water. But this effect is temporary.

As you lose weight, you lose some muscle along with fat. Muscle helps keep up the rate at which you burn calories (metabolism). So as you lose weight, your metabolism declines, causing you to burn fewer calories than you did at your heavier weight.

Your slower metabolism will slow your weight loss, even if you eat the same number of calories that helped you lose weight. When the calories you burn equal the calories you eat, you reach a plateau.

To lose more weight, you need to either increase your physical activity or decrease the calories you eat. Using the same approach that worked at first may maintain your weight loss, but it won't lead to more weight loss.