Hmmm: I've never heard of puffy eyes as a side effect of metformin or low-carbing, but I often hear of it being a side effect of too little sleep.

What exactly is going on with your eyes? Are they irritated or red? Is the skin around them painful?

Just to brainstorm possible causes: do you have allergies? Have you been around smoke from a barbecue or campfire? Any new makeup, shampoo, soap or other facial product?

Hope you solve the mystery.