The amount of calories you burn per day is correlated with your weight. If you decrease your calorie intake by 20% you will lose weight until you reach the bala

The amount of calories you burn per day is correlated with your weight. If you decrease your calorie intake by 20% you will lose weight until you reach the balance point where the new weight burns 20% less calories than your original diet. As long as you continue to maintain the reduced calorie intake you will continue to maintain your new weight. There's more nuance than just that of course, but those are the broad strokes.