When I first got serious about a 16:8 IF, my girlfriend started telling me I needed to go to the dentist because my breath was bad. So I went expecting some rotting tooth or something. No cavities, no anything. I did some research, when you are burning that much fat on IF, it will produce a weird smell, it my case, I was exhausting it in my breath. It wouldn’t surprise me that different BO would happen as well.
Bad breath link.
https://www.healthline.com/nutrition/intermittent-fasting-side-effects#9.-Malnutrition
BO is about biome on the skin in your arm pits. The stink is from microbes that live there eating the old sweat. You can wipe out and around your armpit with a dab of rubbing alcohol on a wash cloth to kill the stink. You may to switch up deodorant.
From what I understand, because you’re in ketosis your body is expelling more of its reserve fats (and reserves in general, such as toxins that have built up). If your sweat smells bad, you might be expelling more toxins. Drink tons of water to keep getting all that out.