eat up a storm or eat a storm
To eat a storm is to eat so much that your face looks like it’s about to explode. You’re not eating, you’re warping your body with food.
My cousin ate a storm and looked like a balloon that was about to pop.
At the birthday party, my brother ate a storm and couldn’t walk straight after.
I ate a storm and my face was so full, I looked like a pumpkin.