I don't wear this under a wetsuit, I wear it alone. The reason I wear this is protect me from too much sun and also from any stinging, rash causing, critters I might encounter during my snorkel. I like to snorkel shallow water, so I have to swim through sea grass. I would get a rash from the grass (or critters on and in the grass), this skin keeps me rash free. I snorkel warm water, Florida Keys. So I didn't get this skin for warmth, just protection. I am overweight and was concerned that I would look ridiculous in the skin, but to be honest it wasn't too bad. So don't let being a bit chubby stop you from getting one. I wear size 18-20 in jeans, and the XXX large was good for me. The legs were a little long, but I just tucked the extra into my dive boot. I would not have been able to wear the XX. Good luck!