I believe it would work but you would have to eliminate everything from your diet that would cause an odor. Your diet would consist of boiled potatos and green vegetables with no spices on them. You said you eat garlic and onions, you wouldn't be able to. I dated a girl once and you could smell the garlic coming out of her pores.

Personally I try not to eat spicy foods a couple of days before I go out but I'm not that strict about my diet.