You can lose weight and improve your health and body composition with diet or exercise, but it shouldn't be a case of either/or. By far the best approach is to partake in an intelligently planned training routine and eat a healthy, balanced diet. Your diet should not only support your health and weight goals, but also improve your training performance.
Earning Your Carbs
As a fit, active individual, your body needs more carbs than if you were sedentary. Carbs are your body's main source of energy. If you're an athlete, you need between 2.2 and 4.5 grams of carbs per pound of body weight each day, according to a report from Brown University. If you're only exercising for recreation, however, you may not need quite this many carbs, whereas if you're extremely active or a competitive athlete you'll need toward the higher end. Your carb intake should come mainly from high-fiber sources, such as whole grains, starchy vegetables, beans and fruit.
Bump Up Fruits and Vegetables
Fruits and vegetables are a foundation of good health. Ideally, you want as big a range of colors as possible. Think red from tomatoes and strawberries, orange from carrots and oranges, yellow from corn and pineapple, green from broccoli and peppers and so on. The President's Council on Fitness, Sports & Nutrition recommends dedicating half your plate at every meal to fruits and vegetables.
Powerful Protein and Fantastic Fats
Once you've got your unrefined carbs, fruits and vegetables in, it's time to consider protein and fats. Include a source of lean protein at every meal, from sources like chicken or turkey breast, low-fat cheese and yogurt, white fish or soy. You'll find healthy fats in oily fish, olive oil, eggs and different types of nuts and seeds. Get some fat into every meal either by switching a lean protein for one richer in heart-healthy fat -- for example, opting for grilled salmon over skinless chicken breast -- drizzling oil over your vegetables or having a small serving of nuts, seeds or cheese.
As a minimum, you need 2 1/2 hours of moderate or 1 1/4 hours of vigorous cardio each week, with an optional two or more strength-training sessions. Use your exercise performance to judge the success of your diet. If you're maintaining your weight, or losing body fat and feeling good, it's likely your diet is doing what it should. If you're gaining weight, you'll need to reduce your calorie intake a little. If your exercise performance and energy levels are dropping, you may need to eat more, or look at reducing your consumption of high-sugar, processed foods and eating more fibrous carbs, fruits and vegetables.