Calories are calories. There's nothing magical about protein calories that makes them less fattening than carb or fat calories. It is just that proteins and fats take longer to digest so the body feels satiated longer than it does on carbs, so you eat fewer calories overall. There is some chemistry involved that I'm not addressing that makes a small difference between types of carbs (high glycemic versus low glycemic), but the bottom line is that your body stores whatever excess you take in regardless where it comes from. Once your muscle glycogen stores are full up your body stores the excess as fat. If we don't exercise and burn the muscle glycogen stores then most of what we eat gets stored as fat from the get-go. Most people could live for days without eating, although it isn't easy (or fun) when your body is converting fat to energy. This is a simplistic answer to a complex phenomenon, but the saying holds true: calories in should equal calories out or you will gain weight. That is, as long as you have a normally functioning thyroid. If your thyroid is out of whack then all bets are off.

MNS