When to Take L Carnitine for Weight Loss & Maximize Results L Carnitine injection is recommended at 1 ampule every 2 3 days for best results. The L Carnitine is taken intravenously either by normal injection or using a butterfly needle. After taking this L Carnitine, you When Nicks in a calorie deficit, Acetyl L Carnitine is non negotiable., Why?, Helps convert fat into energy, Keeps the brain sharp, Supports endurance and focus, Cutting doesnt have to mean L Carnitine is Underrated. New Meta Review Reminds Us Why.