I agree, he is too heavy. I say it all of the time, but people like the look of a plump horse to the point, they do not even know they have plump horses more often than not.
I cannot really tell in the photos, mainly because I'd need to see a similar pose, but 40lbs in a horse is hard to detect unless you see them in person, I feel.
I think it is great you know he needs to loose. I have a pony I am trying to get some weight off of, and it is not moving!