Assuming a similar level of physical activity, if you have two guys, one who weighs 180 pounds with only 10% body fat and another guy who weighs 200 pounds with 40% body fat, I'm fairly confident that the leaner, more muscular guy who weighs less will have the higher metabolic rate.
My example was for someone who had lost weight not a comparison between 2 guys. Anyway, the exercise energy expenditure will definitely be greater for the heavier guy, but basal metabolic rate may be greater for the leaner chap. I would need to calculate it, which, atm, i cba.
I was using two people as an example to better make the point. You can apply the principle to the same person, who embarks on both losing excess fat and gaining muscle.
Weight loss in one person affects that person's basal metabolic rate differently due to metabolic adaptation than comparing 2 guys at different weights.
That seems like a fair point. But as the person continues to eat and exercise properly, he will eventually lose excess fat and gain lean muscle tissue. So, for the sake of argument, if he went from 200lbs to 180lbs while reducing his body fat from, say, 40% to 10%, my guess is that his basal metabolic rate would increase between his start and end point because of the higher lean tissue content, which is metabolically more expensive than fat. I'm just spitballing here with the numbers, but you get the general idea.