I can't notice any big issue with the weight of your dog from these photos. I think he looks fine as others say.

A lot of people say that their dog doesn't eat anything but they usually eat more than their owners realise.

Here is a quote from one of John Fishers books:

"The finicky eaters usually worry their owners by hardly eating enough to keep a fly alive, when in fact they probably have a very low metabolic rate and don't need as much food as the owners think they do. Often they have learnt to play the game 'I can't eat that, it's dog food - give me a steak'; their reward is that the owner usually does. Another good ruse is 'how to get attention' and lots of picky eaters end up being hand fed. These dogs are not anorexic, they are usually just brats."

The anorexic part was mentioned because this quote came from a section about anorexia in dogs...which is different to that in people of course...not a fear of getting fat, lol.