2 Activity versus dieting
In Reading 1, Sharkey and Gaskill refer to several studies that point towards the need to include physical activity in weight-control programmes for successful longer-term outcomes. This is because restricting calorie intake alone, by dieting, leads to a loss of lean tissue (muscle mass) and body water in addition to fat. They emphasise that when the body loses lean tissue it becomes less able to burn calories due to the decreased metabolic rate, and so when energy intake increases again, fat is regained more easily than prior to the calorie-restricted diet. Weight loss with exercise allows the decline in body fat levels without the accompanying loss of lean tissue. Indeed, exercise will increase lean tissue and thus increase basal metabolic rate (BMR). Sharkey and Gaskill conclude that exercise and dieting combined is more effective than dieting alone.