I am not a teacher.
I'm afraid this doesn't make sense.He and he is the same person.
This should be comparing the weights of two different people, but the distinction between the two, as written, is not very clear. In a real life situation with some pointing and hand waving it might be clearer.He weighs as much as he does.
As an afterthought, if the sentence were to continue it might make sense.
He weighs as much as he does because he eats like a horse.
Student or Learner