Personally I think the China and Italy are REALLY low bmi, maybe healthy but barely.  Spain is definitely a chubby chaser.  The whole thing is bogus though since it was just one guys opinion.  The way you do these studies, and I have (though not for weight) is you have a range of these, and get a few 100 to a few 1000 people to judge which figure they like best.  Ideally  it would be a silhouette so things like hair color and race don't play a part in it.