Strange Feelings...

So, I've started feeling very weird and just as of this moment right now realized it. I'm starting to feel like every time I eat for I am definitely going to gain weight. Even if I'm well within my calorie limits. I am making tortilla chips right now with half a cup of refried beans for a small snack. I haven't eaten anything all day but my brain keeps screaming "Don't eat! Don't eat! You'll get fat!!!" My heart kind of hurts with the conflict of reality and my minds made up notions. What is going on?! I know the truth, why is it so hard to tell myself otherwise?