To maintain a healthy weight, eat a healthy diet. This means limiting fast and processed food and trying to eat plenty of fruits, vegetables, grains, protein, and low fat dairy products. The key to a healthy diet is eating everything in moderation. Don't skimp on important nutrients such as protein, calcium, potassium, healthy omega-3, fats, and folic acid. Ask your doctor about vitamin supplements. Be sure to get 30-60 minutes of exercise per day, as exercise contributes to a healthy weight.