I'm sorry but you cannot judge a person's size on their clothing size!! Even when I was underweight I was still in a US size 6 jeans just to fit over my wide hips. The rest of the pants were hanging off me and made me look like I had a saggy bum, but if I went smaller I wouldn't be able to get them over my hips. Same now! (even though I'm not longer a 6), I generally have to go to a 14/16 to get over my hips, but they still sag at the back and legs. For shirts I generally have to go to a M or L and always have in order to go over my shoulders/boobs and cover my long waist.
There's no rhyme or reason to clothing sizes. I can fit into size 8 maxi dresses, but can't get a pair of size 14 jeans buttoned?
We're going off the OP's (who funnily enough hasn't been back) clothing size, which yes, is the above average size. However, we don't know if she carries her weight like Ashley Graeme (whose hour glass figure means she's quite healthy at her size) or Chris Farley (apple and all around the middle).
We can't base health off a clothing size.
Funnily enough, I live in Dubai where most of the clothes come from the UK, and just yesterday my co-workers and I, who come from the Phillippines, China, South Africa and Holland (myself from Canada), were saying how we hate UK sizes because they don't make sense! Even the chubbier Asians (who are definitely overweight), can't fit into the smallest sizes because the clothes are so big, while the Dutch and South African ladies were saying that, even though they are very slim!, they had to go three and four sizes bigger than they would normally would because the clothes are made for petite women. It's insane!