If extra body weight were disabling, all those beefy gym rats and football guys who must weigh a ton more than less muscular people would therefore be disabled by their extra body weight, but they're obviously not. I've always thought the same thing goes for the argument that carrying extra pounds of fat is bad for the heart simply because of the extra blood vessels inside that fat that the heart must pump blood through. Muscle's got to have a lot of blood vessels supplying it, too, yet you never hear people complaining about how bad all the extra distance pumping through all that excess muscle must be for the heart. Or any complaints about stressing our hearts and being bad lifting iron in the gym compared to lifting our own bodies to move around if we're obese. We had one of those body fat scales that measures your lean (muscle, bone etc.) mass and I was amazed at the huge amount of sheer muscle of someone morbidly obese that tried the scale. Obese, yes, but hugely muscular underneath from the daily exercise of moving a heavy body around. So something else likely not about body heaviness/difficulty of moving heavy things is going on. And it sure can't help that when hormones are out of whack making you gain body fat that your body is partitioning needed fuel away from other working organs like muscles, heart and brain to the fat cells. Not surprised dopamine and who knows what else could be messed up under such conditions. I'm glad to see some researchers taking obesity scientifically seriously rather than the tired old bigoted insults of overeating and laziness that get hurled at heavy people.