While resting between sets of lunges (can you feel my pain?) this morning, I got into conversation with my trainer (my way of "resting" between sets is to jabber and get her to forget how long I have been resting) about how we all look at what people have in their supermarket shopping carts and make judgments about them. Look, I do it even if you won't admit that you do it.
You see someone who is fat (fatter than you). She/he has ice cream in the cart. You say to yourself, "That explains it." What you're really saying is, "I wish I had the guts to buy ice cream. I really want some."
You see someone who is drop dead gorgeous--svelte, buff, tanned--everything you are not. He/she has ice cream in her cart. You say to yourself, "She probably eats it and throws up."
What you're really saying is, "Life's not fair. How come she can eat that high calorie stuff and stay slender?"
Intuitive eating would recommend you not torture yourself. Buy the ice cream. Feel no shame or guilt. Eat enough to feel satisfied. And forget about what other people are doing!