No, its a rejection of destructive fats.
Its all ablut the fats and what they do to your cell membranes, not what kind of diet you’re on. The diff between vegies and meaties is that the vegies consume far more starch, and thus have a higher static glucose level to deal with. It wouldn’t matter if the glucose could enter the cells to be metabolized, but it cannot due to the unnatural fats that make up the cell membranes.
To put it simply, if you used all saturated natural fats it wouldn’t matter what your preferences between meat and vegetables was. Most weight gain is directly caused by the high glucose. The fibro myalgia would cease too, since it is mostly due to the low blood oxygen levels that result from the anaerobic metabolism caused by high blood glucose.
The Japanese use a fair amount of soy and yet do not seen to suffer from it.