Does TRT help you lose fat? Sometimes yes, sometimes no. Here’s the actual science and what to expect.
Yes, testosterone replacement therapy (TRT) often reduces body fat. But here’s the catch: it only reduces fat in those who are truly hypogonadal (diagnosed with low T by a doctor). Similarly, body fat is also reduced in previously untrained individuals given supraphysiological doses of testosterone.
But anecdotally, most bodybuilders tell you that testosterone isn’t very effective at reducing fat. Various “stacks” used while dieting may incorporate testosterone, but this is mainly because of its purported ability to maintain lean mass during periods of calorie restriction, not its ability to decrease fat.
We have some data on that, too. Testosterone is effective at increasing lean body mass or preserving it but not very effective at reducing fat mass, at least when exogenous testosterone is given to subjects who are already trained or physically active.
For example, in a study looking at healthy recreational athletes who train at least twice per week, those given 250 mg a week of testosterone esters (Sustanon) for five weeks had a significant increase in lean body mass but very little change in fat mass compared to those receiving a placebo or growth hormone (1).
Another study used a group of healthy, physically active men. They were given either 200 mg per week of testosterone enanthate or a placebo for four weeks (2). During this time, they were placed into a 55% exercise and diet-induced energy deficit designed to mimic stressful military combat conditions.
Interestingly, while the testosterone increased lean mass beyond that of placebo, even during an energy deficit, changes in fat mass in the testosterone and placebo groups were effectively identical.
- If you’re truly hypogonadal or completely untrained, testosterone supplementation may moderately decrease fat mass.
- However, if your testosterone levels are already normal and you’re an intermediate or advanced lifter, don’t expect testosterone to do much for reducing fat.
Even worse, if you think those TRT ads with a guy getting a six-pack simply from taking testosterone are accurate, well, don’t count on it.
- Meinhardt U, Nelson AE, Hansen JL, Birzniece V, Clifford D, Leung KC, Graham K, Ho KK. The effects of growth hormone on body composition and physical performance in recreational athletes: a randomized trial. Ann Intern Med. 2010 May 4;152(9):568-77. doi: 10.7326/0003-4819-152-9-201005040-00007. PMID: 20439575.
- Pasiakos SM, Berryman CE, Karl JP, Lieberman HR, Orr JS, Margolis LM, Caldwell JA, Young AJ, Montano MA, Evans WJ, Vartanian O, Carmichael OT, Gadde KM, Johannsen NM, Beyl RA, Harris MN, Rood JC. Effects of testosterone supplementation on body composition and lower-body muscle function during severe exercise- and diet-induced energy deficit: A proof-of-concept, single centre, randomised, double-blind, controlled trial. EBioMedicine. 2019 Aug;46:411-422. doi: 10.1016/j.ebiom.2019.07.059. Epub 2019 Jul 27. PMID: 31358477; PMCID: PMC6711889.