To be honest, w00h00, it's really all down to you, how open you want to be and primarily how you work with the photographer, a good snapper, male or female, should be able bring out the very best in you. I've done 20 or so shoots like this for ladies of most shapes and sizes and with exception of one lady (who happened to have the most incredible body) the results have been superb. It's nothing to do with the photography it's all to do with the subject.
The one I called a halt to was difficult, we had a meet up before the shoot for to try and get a feel for what she wanted out of it, put a pile of ideas to her and by the shoot she would have a strong idea of what she wanted. After half an hour it was obvious she was there to tease, not to get a set of images for her partner, it pushed the edges of my own professionalism so I stopped it.
My wife used to weigh over 24stone, she now weighs 11 and a half and the joy she gets when she see's classy images of herself is just amazing. Go for it but dont go into things with a closed mind find a good photographer and you'll enjoy the experience