Hi charl, I’m very slim and just had 410 overs, it depends what you want, and how big your rib cage is and how big you are now, 310 can look big on one person and little on The next,you need to try a few sizes on with the clothes you normally wear! I started off wanting the natural look and not too big….to going quite big (look at my pics) but they look fab! Do lots of research! Xx