There is a misconception that after starving yourself down (so as to lose significant amounts of weight), your body will replace the lost tissue with fat when you begin eating right. As someone who has been there, this is totally wrong. The body has a desired amount of muscle mass it likes to maintain. This is usually genetically determined, although lifestyle (e.g. weight lifting) and health (e.g. growing old, having a wasting or energy utilizing disease like diabetes) can affect it.

Once you starve yourself and create energy deficits so large to the point where you lose lots of muscle in addition to fat. When you begin eating more, your body starts to replenish that lost muscle to it's desired level. It does this simply by eating a nutrient adequate diet.

In other words, the myth that you lose 5 lbs of muscle and fat each, and regain 10 lbs of fat is just that, a myth. In fact, you may lose more body fat when recovering from mild restriction, just by increasing the metabolically taxing muscle anabolism. I feel this is the physiologic behind cyclical dieting. Eating more food after extensive restriction increases the rate of positive compensatory LBM anabolism. This then creates an energy deficit even larger than you enjoyed before. The net effect is more body fat loss for more muscle. Cyclical dieting, when done correctly, is ideal for preserving LBM and losing body fat IMHO.