I'll help you with 2 perspectives. Before diagnosis, my daughter 11 at time, looked like she came from a 3rd world country. Twiggy arms and legs and a big bloated belly, couldn't stand anything tight.
Me on the other hand not Celiac, but lets just say rather on the "fluffy" side. Tight belts don't bother me a bit,just gives me incentive to try and suck...