Huge kitty.

I have a 4 - 5 month old Norwegian Forest cat mix kitten and he's huge. He has 3.5 kg and he doesn't look so thin like other street cats. Since he's a kitten he eats whenever he wants, but that's not too much. I'm worried is it ok for a 4 - 5 month old kitten to have

3.5 kg?  I know some female cats stop growing at 2.5 - 3 kg. But my thing is still a 4 month old baby.  

Norwegian Forest Cats are a large breed, so it may not be unusual for him to be that large at 4 - 5 months.  I wouldn't expect him to be as thin as a "street cat" if he is getting regular meals.

Is he the cat in your Avatar?  If so, that cat certainly does NOT look overweight