What's Actually Happening
Total testosterone in men declines gradually from around age 30 onward, and the rate accelerates for many men after 40. When levels fall low enough to cause symptoms — reduced muscle mass and strength, increased fat mass (particularly visceral), fatigue, low libido, mood changes, and reduced bone density — that's generally referred to as late-onset (age-related) hypogonadism. Major urology and endocrine societies (ISSAM, EAU, ESE, EAA, AUA) generally define the diagnostic threshold in the range of 250-350 ng/dL total testosterone, but diagnosis requires both a low lab value on repeat testing and actual symptoms — a low number alone, on its own, isn't a diagnosis.
What Resistance Training Actually Does (and Doesn't Do)
Here's where it's worth being precise instead of repeating gym folklore: the evidence does not support resistance training reliably raising resting testosterone in older men. A systematic review and meta-analysis (Hayes & Elliott, Frontiers in Physiology, 2019) pooling resistance training studies in older men found essentially no effect on basal testosterone (standardized difference in means of −0.003 — statistically no different from zero), while endurance and interval training showed small positive effects in the same analysis. If the goal is specifically raising a lab number, resistance training by itself is not a reliable way to do it.
That doesn't make resistance training irrelevant here — it makes the honest case for it different. Resistance training reliably preserves and builds muscle mass, improves body composition, and improves physical function and mood independent of what it does to a testosterone number, and it appears to work synergistically with testosterone therapy when both are used together, which is a genuinely useful finding for anyone actually managing this condition medically. But if the specific goal is raising testosterone itself, the next section is where the real lever is.
What Actually Does Raise Testosterone: Fat Loss
If resistance training itself doesn't reliably move the number, something else might — and the evidence for this one is considerably stronger. Body fat is hormonally active tissue: it contains aromatase, the enzyme that converts testosterone into estrogen, and excess fat (especially visceral fat) drives hyperinsulinemia, which lowers sex hormone-binding globulin (SHBG) — the protein that carries testosterone in the blood. More body fat therefore isn't just correlated with lower testosterone, it actively suppresses it through two identifiable mechanisms.
A systematic review and meta-analysis of 24 studies (Corona et al., European Journal of Endocrinology, 2013) found that weight loss — through either low-calorie diet or bariatric surgery — significantly increased total testosterone in men with obesity, with a clear dose-response relationship: the more weight lost, the greater the testosterone increase. Diet alone was enough to move the number; surgery produced a larger average increase, consistent with the larger average weight loss.
A 52-week randomized controlled trial in 118 overweight and obese men (Moran et al., PLOS ONE, 2016) found total testosterone, free testosterone, and SHBG all rose significantly with sustained calorie-restriction-driven weight loss — and it didn't matter whether the diet was higher-protein or higher-carbohydrate, the effect held either way. This is a genuinely actionable, well-evidenced lever: reducing excess body fat through a sustained calorie deficit is a more reliably effective natural way to support healthier testosterone levels than resistance training alone.
The Evidence
A randomized, placebo-controlled trial in 148 men with low-normal to low testosterone (Midttun et al., Journal of Cachexia, Sarcopenia and Muscle, 2024) tested testosterone therapy, resistance training with protein/calcium/vitamin D, both combined, or neither. Only the combination — training plus testosterone therapy — improved chair-stand performance, muscle strength, and quality of life, and reduced fatigue and leg fat; neither intervention alone matched what the combination achieved. A 1-year follow-up of a related trial in frail older men (The Aging Male, 2024) found the same pattern held over the longer term: only the group receiving both testosterone and resistance training improved on physical performance and fatigue measures.
For a broader look at testosterone replacement therapy itself — benefits, safety considerations, and current clinical thinking — see this 2025 narrative review in men aged 50 and above. It's a narrative review rather than a randomized trial, so treat it as a useful overview of the clinical landscape rather than definitive proof of any single claim.
Where to Start
If you suspect low testosterone based on symptoms, the correct first step is a physician-ordered lab panel (typically a morning total testosterone, repeated to confirm) and a real conversation about whether treatment is appropriate for you — not a supplement stack or an over-the-counter test. If excess body fat is part of the picture, a sustained, moderate calorie deficit is the single most evidence-backed natural lever for improving the number itself. Pairing that with structured resistance training 2-3 times per week covers what the fat-loss trials alone don't: preserving (or building) the muscle mass that a calorie deficit would otherwise put at risk, plus the functional and mood benefits that show up regardless of what happens to any lab value. Combined, that's the most defensible “natural” approach the evidence actually supports — whether or not testosterone therapy ends up being part of your plan.