Carnitine moves long-chain fats into mitochondria so you burn them for ATP. It’s not a stimulant, so it doesn't interfere with your CNS, and it actually helps you last longer, recover faster, and hold muscle while cutting.
L-Carnitine is synthesized in the liver/kidneys from lysine + methionine. Its entire personality is being a
fat taxi: it binds long-chain fatty acids, drives them across the mitochondrial gate, and hands them off for
beta-oxidation → acetyl-CoA → ATP.
Food contains some (red meat, poultry, fish, dairy). For athletes, “eat steak and pray” usually isn’t enough when you’re chasing endurance or a leaner power-to-weight ratio. That’s where supplementation comes in, especially
injectable when you want plasma levels that actually move the needle.
Carnitine benefits
- Fat oxidation & body comp: more fat used for fuel during training, easier to peel fat while protecting lean mass.
- Glycogen sparing: shifts energy toward fats.
- Recovery: less oxidative stress and soreness, better blood flow, faster turnaround between sessions.
- Anaerobic assist: less muscle damage means more reps and volume over time.
- Cardio support: cardiac muscle runs better on fats too.
- Brain perks (ALCAR): Acetyl-L-Carnitine can cross into the brain, supporting acetylcholine, focus, and mental clarity.
- Metabolic help: better insulin sensitivity and lipid handling.
- Fatigue syndromes: mitochondria run cleaner; some people with CFS/fibro report less fatigue and brain fog.
Oral vs injectable Carnitine
- Bioavailability: oral is low (5–18%), due to first-pass metabolism. Injectable bypasses the gut and hits the blood hard.
- Onset: oral peaks after hours. Injectable is felt within minutes.
- GI tolerance: oral can annoy your stomach at higher doses. Injectable avoids that but can irritate the site if you’re sloppy.
- Use-case: if you want real, acute performance or fat-use effects around training, injectable wins.
Dosage
- 500–2000 mg/day.
- Timing: 30–60 min pre-cardio on cutting phases, or morning fasted for general energy support.
- Rotate injection sites.
What Carnitine is not
It’s not a fat burner you “feel.”
It won’t out-perform a trash diet or lazy programming. If your sleep and protein are clownish, start there.