I’ve noticed a huge decrease in body odor on the carnivore diet. I actually don’t even wear deodorant any more because of it. But my nose has gotten more sensitive for other people’s scents, so I don’t think it’s just perception.
Fasting (or any diet that puts you into ketosis) can cause temporary unpleasant odors from ketosis if you aren’t already in ketosis yet. That goes away if you stay in ketosis or really close to it for at least a few weeks.
The OP is not asking if the dry fasting is causing bad breath or BO. Theyre asking if dry fasting would have a beneficial effect on these two conditions, by way of killing off the bacteria in the gut that might be possibly causing these issues.