Hahaha....there are these silly girls in my hall who do this ALL the time. I've gone out with them when it's just the girls, and they pig out. But if there is even the slightest hint of a boy in the air, they will order a soda, and that's it. It's hilarious, like they are afraid the guys seeing them eat will disgust them. I can see how it would make someone self-conscious (think about how you look stuffing lettuce froma salad into your mouth), but everyone eats, so guys are most likely used to seeing it by now.
I did used to have a little anxiety about eating huge burgers in front of my husband when we were dating, like he'd think I looked gross shoving huge amounts of food into my mouth. So, I can sort of sympathize.