I would think the body would do something similar to the salivation, ie get excited at the prospect of the buzz , but not actually be anything like the effect of the drug
pretty much this, as I said before, you'd probably just end up craving drugs all the more, probably have the complete opposite effect desired for rehab
Is it food or a certain ingredient you crave? ie sugar
I find now that I don't eat sugar or carbs much I don't crave anything or feel hungry that often
It's been proven in studies that children growing up on sugary foods have a major addiction to it, and has been likened to drug addiction in some cases
It was a joke based on the fact you would die without eatting... 



Also it would only, if at all work on those addicts who had a major pyschological dependance in the first place as the relationship worked for the dogs due to food being their main desire, although its quite a interesting idea ... perhaps someone should do the research if not for those pesky ethical dilemia's