- Weight-loss diets: Restrict the intake of specific foods, or food in general, to reduce body weight.
- Weight-gain diets: Many professional athletes or underweight individuals impose weight-gain diets on themselves.
Unless a doctor says otherwise, low-carbohydrate, low-fat, or other specialty diets for children who are not heavily obese are unhealthy because they deprive the body of the essential nutrients.
Physical exercise
Physical exercise like walking, climbing stairs, doing housework is an important complement to dieting in securing weight loss in addition to Aerobic exercise like brisk walking which maintains the muscular strength of the heart.
Fat loss versus muscle loss
A dieter can lose weight without losing much fat. Ideally, overweight people should seek to lose fat and preserve muscle, since muscle burns more calories than fat. Muscle loss during weight loss can be restricted by regularly doing strength-oriented exercises and by maintaining sufficient protein intake.
Dangers
Extreme calorie restriction, medication or unusual patterns of eating can be dangerous and cause Anorexia, Depression, Reduced sex drive, Fatigue, Irritability, Fainting, Seizures etc and can even be fatal. A nutritious diet consisting of all the essential nutrients ensures a healthy body, both physically and mentally. There are seven main classes of such nutrients that the body needs: carbohydrates, proteins, fats, vitamins, minerals, fiber and water. Poor health can be caused by an imbalance of nutrients, either an excess or deficiency, which, in turn, affects bodily functions cumulatively.