I'm also looking at getting one of these and was going to ask about sizing, as never bought a one piece before. I'm 6ft1 and reasonably slim. My main worry is about the body length, and if I get a XXL if it will be super baggy in the body.
"direct sunlight.
Size Guide (Japanese Sizing – Smaller than EU/US):
M: Height 155–165 cm | Weight 45–55 kg
L: Height 160–170 cm | Weight 50–60 kg
XL: Height 165–175 cm | Weight 55–70 kg
XXL: Height 170–185 cm | Weight 60–80 kg"
Follow what Leohex say. It's not going to be baggy. You might be able to squeeze yourself into an XL, there are various different Leohex swimsuits / leotards which all fit differently to each other.