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 Research Science Update L Carnitine L Tartrate Supplementation Impr Prosource Acetyl L Carnitine (formerly Carnityl) 60 Count By Thorne Research Beneficial effects of l carnitine supplementation for weight management in overweight and obese adults: An updated systematic review and dose response meta analysis of randomized controlled trials ScienceDirect