Made by the body from amino acids
L-carnitine
Limited evidenceShuttles fat into mitochondria, though supplements rarely move the needle for fat loss.
What it is
The body makes L-carnitine from lysine and methionine. It transports fatty acids into mitochondria, where they are burned for energy.
Food sources
Red meatDairyFish
What the research shows
- In healthy people eating a normal diet, supplements show limited effect on fat loss.
- Research on recovery and specific medical conditions is mixed.
Read the published research on PubMed →
Food first: most people get what they need from a varied diet with enough total protein. Talk to a provider or registered dietitian before adding a supplement, especially if you take medication or have a health condition.
Similar evidence level
Conditionally essential amino acid
Arginine
A precursor to nitric oxide, though oral supplements are poorly absorbed for that purpose.
Limited evidenceConditionally essential amino acidGlutamine
The most abundant amino acid in the blood, often oversold for muscle recovery.
Limited evidenceNonessential amino acidGlycine
The simplest amino acid, a major part of collagen, and studied for sleep.
Limited evidence