I am quite thin and athletic, and a few of my friends are heavier than I am. They never want to go shopping with me and oftentimes exclude me when they go to the mall. On the rare occation I get invited, they make cracks at how thin I am. It's actually making it hard to be friends with them. They make weight such an issue. How can I approach this in conversation without hurting their feelings? Why do you think they do this? Have you ever discriminated against someone because they were too big or too small?