Published in 2020 this systematic review and meta-analysis was conducted with a highly sensitive search. 33 trials demonstrated an average reduction in BMI of 0.24 kg/m2 in the supplementation group over the control group. Twenty-four trials (with 1520 participants) provided data for weight change and demonstrated statistically significant reductions in the weight of overweight individuals. Overall, the authors concluded that supplementation of 370-4000 mg/day for three to 48 weeks was safe and well tolerated and has modest reductions in body composition parameters for overweight and obese patients.
Talenezhad N, Mohammadi M, Ramezani-Jolfaie N, Mozaffari-Khosravi H, Salehi-Abargouei A. Effects of l-carnitine supplementation on weight loss and body composition: A systematic review and meta-analysis of 37 randomized controlled clinical trials with dose-response analysis. Clin Nutr ESPEN. 2020 Jun;37:9-23. doi: 10.1016/j.clnesp.2020.03.008. Epub 2020 Apr 18. PMID: 32359762. https://pubmed.ncbi.nlm.nih.gov/32359762/