That approach is based on the old carbohydrate-based way of thinking. True muscle loss does not occur quickly. First glycogen is used up, then fat, then muscle. Carbs are the least efficient fuel and people who suffer from low energy without food are "addicted" to carbs, meaning their body is in a constant state of insulin over-production. Weight lifting will always produce more fat loss than cardio, but it happens in a delayed fashion. Ideally, one would fast in the morning, lift weights, eat, then remember never to eat past 8pm. This would produce the highest spike in growth hormone and use stored fat to build muscle. The protein for this action is stored in the blood from the previous meal.