L carnitine is a naturally occurring amino acid structure that is made in the human brain, liver, and kidneys. L carnitine plays a critical role in energy production, as it converts fat into energy. Early research into L carnitine was often cited as underwhelming, showing negligible changes in muscle carnitine content and fat loss outcomes. However, these findings may have been limited by a short study window L Carnitine: Benefits, side effects, and dosage L Carnitine Pills for Weight Loss: Evidence, Safety and UK Guidance Bolt Pharmacy Impaired brain function improved by l carnitine in patients with cirrhosis: evaluation using near infrared spectroscopy Scientific Reports