I bought this costume for my son's communion in May. He turned 8 in February so I bought him a size 8 suit. My son has always been a slim kid and this suit is definitely for slim people. I noticed that after eating as his stomach got bigger there was some tension on the buttons in the stomach area lol. Another thing I found strange was that the color of the waistcoat was red on the inside and the tie was blue. It didn't bother him, but it might be different for some people. Overall I was happy with the costume but just wanted to know that slim definitely means slim.