I dont really care too much about belt promotions to be honest. However, a gentleman came into my gym the other day weighing about 400lbs and had recently been promoted to purple belt. I know who promoted him, and the instructor is a legit bad ass black belt. That being said, the portly gentleman could not do any kind of armbars, triangles, omaplatas, or basically any offense off of his back. In addition, his guard passing was atrocious. Now, out of curiosity, is there a certain point where a guy is just too damn fat to be promoted because he simply cannot perform basic elements of jiujitsu due to his weight? I am sure the gentleman had awesome weight distribution from top and his takedowns were ok for a non wrestler. Are the weight classes so vastly different that even things like armbars can be dismissed at extreme upper weights for promotion past white belt? Curious if I am out of line with my thought process.