As you lose weight your fat cells become more efficient at utilizing energy from the food you eat which can lead to gaining weight as fat stores, even though your energy intake may remain the same.

To lose weight, exercise more or eat fewer calories than is recommended. To gain weight, increase the number of calories you eat while maintaining a moderate activity level. Read more about making smart food choices and find recommendations of how much to eat, organized by activity level.

You'll want to make sure you're eating the right foods too. High-calorie foods full of saturated fat and processed sugars tend to increase body fat instead of lean body mass. Instead, add nutrient-rich foods like fish, chicken, eggs, turkey, tofu, oats, rice, nuts, fruit, and vegetables to your daily diet.