However, some of them provide this weight loss at the expense of health and fitness resulting in continual fatigue, listlessness, apathy with limited fitness-gains due to muscle-loss as well. Atkins is one of these diets (along with any of the other low-carb diets). Low-calorie diets with large deficits end up destroying too much muscle in order to get higher weight-loss rates. Sure you'll end up as a thin twig, but you'll also have no muscle-tone and still have love-handles and a double-chin. It is low muscle-glycogen from low-carb intake that destroys muscle the fastest, eating more proteins may help rebuild the damage afterwards, but it does nothing to ward off muscle-catabolism in the first place.