I would guess overweight in and of itself. Being overweight puts your body in a pro-inflammatory state; a pro-inflammatory state makes auto-immune (etc.) diseas

I would guess overweight in and of itself. Being overweight puts your body in a pro-inflammatory state; a pro-inflammatory state makes auto-immune (etc.) disease more likely. So would be surprised if they were not linked. One way to guage might be to take people are are overweight _but are not gaining weight_ -- and compare them to people who are gaining weight (regardless of current weight). Probably a hard study to do.