Weight loss can be caused by a number of physiological and psychological disorders, and if unexplained weight loss occurs, a medical practitioner should be consulted.
Intended weight loss for health or other reasons involves a number of factors. There are many theories regarding weight loss which encompass genetics, food intake and exercise. There is some evidence of a genetic predisposition to obesity and variations in metabolic function. There is also evidence, however, that while some people weigh considerably more than others but have the same food intake, those who weigh more do less exercise.
Most nutritionists agree that effective weight reduction involves a long-term change in eating patterns and behaviour and a gradual but significant increase in exercise. Fad or crash diets used for a short period actually reduce the amount of muscle and water in the body and weight is rapidly regained once the diet is discontinued.
Approaches to gradual weight loss include lowering fat and kilojoule intake while increasing the amount of fatburning exercise. Fat content is reduced by eliminating junk foods and refined sugar and reducing dairy products and fatty meats. Lowering the amount of fat in the diet should correspond with an increase in the intake of fruit, vegetables, legumes and grains. Drinking around 8 glasses of water a day is also recommended. Exercise involving at least three 20 minute periods per week will increase the metabolic rate and burn fat.