[jtuente]

The key point is the first part of that statement, "eat less because you don't feel hungry". It's not the best worded though, but the alternative "only eat until you don't feel hungry" isn't much better since someone can feel like they're hungry when they aren't really. Also your body burns through the muscles to maintain the composition of the other muscles/hormones of your body, because muscles and fat aren't made of the same components.