hmm..i dont know why there were studies on this issue but i tend to disagree that if one has better body..he/she will have better sex life. If all what the person does is workout and has no social life.. chances of him/her getting laid is quite low.. though, they will definitely attract the opposite gender...but does that always mean they'll end up having sex?...not necessarily... its just desi mentality that if one has better body ...s/he will have better sex life.. thats not always true.
i know some people with good physique who are shy.. i mean too shy to even talk to girls... does that mean they have better sex life.. hmm..could be..but you see my point?
On other hand, there are people who take advantage of being rich and stuff.. and they have better sex life.
I think you misunderstood the question. The question is not if people with hot bodies get laid more than others. It is whether they have better quality of sex when they do actually have sex.