Does Carnitine Cause Body Odor? Lume Deodorant A recurring fishy odor could indicate a larger medical problem. L Carnitine is not a magic fat burner It won't melt fat, build muscle, or replace hard work. The only thing it burns is your money Stick to the basics If you always smell sweaty, sour, or like onions, you need to check your gut because most body odor starts inside; constipation, yeast overgrowth, and poor bile flow create toxic sweat, so Amazon.com: Nutricost Acetyl L Carnitine (ALCAR) 500mg, 180 Capsules, 180 Servings Non GMO and Gluten Free, 1 Capsule per Serving : Everything Else Did You Know? Some people report a fishy smell after supplementing with L carnitine. This happens because certain gut bacteria convert carnitine to trimethylamine, a malodorous compound found in rotting fish.