My advice would be to fill a small plate with something healthy looking, and walk around with it. Drink water, and if anyone suggests that you should be eating anything else, just tell them that you’re staying away from sugar/fat/carbs. Unless your mom is there, anyone else should be able to take the hint and relax.
I don’t know if you allow yourself carbonated drinks, but I find having a glass that looks like liquor (short glass, ice, seltzer with lime looks like a vodka seltzer) in your hand is enough to get people to chill out. I get more pressure to drink than to eat… I don’t know what that says about the people I surround myself with on a regular basis actually.