It sounds like you don't have any equipment at all, and it sounds like you are jumping to the 5d3 right away. While an amazing tool, probably you don't need to spend that money for food photography, especially starting out. Also you'll need to buy lighting, good quality tripod, editing software (if you are doing editing yourself), appropriate background if you don't have a suitable table/wall area, etc.
It like is easier, and possibly actually cheaper in the long run to find a decent food photographer in your area to take the shots you want, and if you see their sample images you'll know you'll be getting a certain quality of output.
If you are going to insist on buying, I'd go for the 5d2, and as neuro said the 100mm f/2.8L Macro IS lens (don't forget to turn off IS when using it on a tripod). Then add a good tripod & lighting, possibly a ring light, and I don't have any specific recommendations on those as I need to research a good tripod myself sometime soon.