In the context of physical health, weight loss is the process of losing body weight, usually by losing fat. To achieve healthy weight loss, most experts recommend a combination of healthy eating patterns and regular exercise. Some people try to lose weight using medications such as fenfluoramine, nicotine or cocaine (see anti-obesity medications), herbs such as ephedra or surgery such as liposuction. Weight loss can also be a symptom of certain mental or physical diseases or disorders, such as anorexia nervosa or wasting associated with cancer or AIDS.


Dieting is the practice or habit of eating (and drinking) in a regulated manner, usually with the goal of losing weight. It is also used in some cases to gain weight or to regulate the amount of certain nutrients entering the body. Generally, "dieting" means eating in a carefully planned manner to reduce excess body fat and reduce body measurements of clothing size. There are a multitude (sometimes confusing) of weight loss techniques, many of which are ineffective. What works for one person may not necessarily work for another, due to metabolic differences and lifestyle factors. Successful weight loss diets are all about energy besides energy. If a person takes in less dietary energy than they expend over a period of time, they can burn fat and lose weight. Diets affect energy in the energy balance component by limiting or altering the distribution of food. Techniques that affect appetite can limit energy intake by affecting the desire to overeat. This can be attempted by focusing on foods that fill up, by the use of certain appetite suppressant medications, or by activities such as light exercise that affect appetite. Other techniques deal with usual or emotional eating. Allocating the energy component is central to fitness and exercise programs. These could also be included as part of a complete "diet". Dieting to lose weight does exactly that: you lose weight, water, fat and muscle. Since the muscles are denser, you lose a lot of weight, but little height. Fat is more voluminous, so a fat loss of three pounds can cause a loss of height. To lose one pound of fat, you need to create a caloric deficit of about 3,500 calories (37,600 kJ per kilogram of fat); therefore, if a person creates a deficit of 500 calories per day, the person will lose about 1 pound of fat per week (5,400 kJ per day to lose one kilogram per week). Weight loss during weight loss can be limited by lifting weights regularly and consuming plenty of protein (0.8 to 1.0 g of protein per pound of body weight (1.76 to 2.20 g/kg) per day is said to be sufficient).