If There's A Genetic Predisposition. . .
. . .To being obese, and the argument yay or nay for that isn't my focus here, then I think there is a role for drug therapy for obesity.
The morbidly obese are at risk when they begin exercise for cardiovascular events. Moreover, orthopedic issues arise for the morbidly obese with exercise as the number of foot-lbs. on their weight-bearing joints are several-fold higher than the rest of us. If we could get them on their way with both diet and pharmacologic or surical means until exercise is safer then I think that's an advancement worth pursuing.
I'm 5'10" tall and I ran the NYC Marathon in 1988 in a little over 3-hours while injured. My weight then dropped from 190 lbs. to 177 lbs. immediately after the race. I was back up to 190 lbs. after replenishing the fluids (it was 70 degrees that day, far too hot for a marathon).
My point is, and I trained for 3-months for that race, that despite vigorous exercise some of us are simply built different than others and metabolism can have just as much to do with weight retention or gain as does lifestyle.
Recent news has pinpointed an alleged obesity gene and hormone. I'll wait for these to gain more seasoning before I form an opinion on their roles.