I am not sure that I ever perceived that the WT teaches that overweight people are less perfect or less spiritual. I do think that the attitude of the witnesses, at least in the US, reflects that of the culture at large. Despite the fact that there is a significant portion of the population, both in and out of the org. who are fat, isn't there a general feeling that being fat is a sign of poor self-control. Since control is a JW cornerstone, this could translate to feeling someone is less spiritual I suppose, but on the other hand, there are plenty of fat pioneers and elders, so it does not seem to be a hindrance to getting 'spiritual privileges'. However, I have heard plenty of catty comments about some obese 'sister', out of her hearing, and suitably disguised with surrounding verbiage about being concerned with her health.
I have lost over 50 pounds myself since leaving the mind control of the WT. In my case, I think the extra weight was a reflection of the unhappiness I felt inside. I don't know about others. But one could speculate, that eating is one of the very few pleasures a witness can indulge in freely. And a person who fights the battle of the bulge could easily reason that there is no need to put forth the great effort needed to lose weight, because Jehovah will take care of such physical problems in the 'new system', which is just around the corner.
truman