If you weigh 140 pounds and spent the last week living on 200 calories a day, you are much, much, much better off eating a large Hershey bar than running three miles.
It's a fact!
Really
Are you an MD with minors in exercise physiology and nutrition, or do you just play one on FR, LOL.
I weigh 140, but I sure eat a lot more than 200 calories per day.