Eat "odor-free" food. A person eating a low-carb diet should be able to avoid food-related bad breath if he chooses foods that are not likely to cause odor. Avoid fishy foods, onions, garlic, scallions, fermented foods, coffee, etc. Fatty foods may worsen stomach reflux, and send odors up to the mouth. Excess fiber or other "undigestibles" can lead to gas and odors coming out the other end.