DO YOU KNOW...your brain requires a minimum of 1,000 Calories daily just to function properly?!! If you are eating as the "average" person, less than 1,500 calories daily, your body is starving.
Starving your body causes your body to "store" most of what you eat. Your body only knows how to store by creating fat. So, eating too little daily makes you fat - faster than if you were "over"-eating.