Not a dog behavior expert over here, but i kinda had the same issue with my dog... Only like gary said, at the age of 3 months.

the way i dealth with it was. I was very firm ... I was very angry and got a bit physical, then i i immediatly put her away for a while ...

she never ever tried anything like that ever again ... When i give her food and put it down she even takes a few steps back and only when i say so, she can eat

i got a feeling that with these kind of dogs that you have to show them from puppyhood that you are the strongest physicaly. Untill they mature and it's all an illusion ;)

now that he is almost 1 year ... I don't realy know if you should try the same approach ... I don't even know if my approach with my dog was a correct method, but it worked...