Should I use L Carnitine on rest days or just before workouts? L Carnitine Tartrate 1000 mg Supplements Vitamin World L carnitine usage ? when to take? On the pack it says empty stomach but i read everywhere it should be taken with meal (carbs) for insulin spike. Also does taking beta Tip: It Works Better on an Empty Stomach, L Carnitine absorbs better when insulin is lower., Thats why a lot of people take it: , First thing in the morning, Before movement