Fertility conversations tend to focus heavily on the female partner, but male factors are involved in roughly half of all infertility cases, either on their own or alongside female-side issues. The upside is that several of the biggest contributing factors are ones a person can actually change.

Heat exposure is a bigger factor than most people realise

Sperm production works best at a temperature slightly below core body temperature, which is why the testes sit outside the body in the first place.

What the research shows

A 2023 observational study published in Andrologia found heat exposure increased the risk of low sperm concentration by more than 74 times compared with men without significant heat exposure, a considerably larger effect than many people assume from something as routine as frequent hot tub use or saunas. The mechanism involves reduced mitochondrial activity and lower ATP levels within sperm cells when exposed to high temperatures.

The timeline for improvement

Because sperm production takes roughly 74 days plus additional maturation time, changes to heat exposure habits typically take 2–3 months before showing up in a semen analysis. This timeline matters for anyone making lifestyle changes and expecting to see results in the next test, patience is part of the process here.

Weight and physical activity matter more than expected

Obesity affects male fertility through a specific hormonal pathway, not just general health.

Excess fat tissue increases aromatase activity, an enzyme that converts testosterone to oestrogen, disrupting the hormonal balance sperm production depends on. The same 2023 study found obesity increased the risk of low sperm concentration by roughly 17 times and reduced motility risk by about 6 times. The encouraging counterpoint: even modest weight loss has been shown to improve sperm parameters, meaning the relationship works in both directions.

What to actually cut back on

A few substances and habits show consistent evidence of harm across multiple studies.

• Smoking: increases sperm DNA fragmentation by approximately 10% and alters hormonal profiles; e-cigarettes may carry similar risk
• Chronic alcohol use: raises DNA fragmentation by a comparable margin and can disrupt the hormonal signalling axis that regulates sperm production
• Recreational drug use: steroids, cannabis, and opioids have all been associated with suppressed fertility in the research literature

Diet and supplementation

The evidence here is real and encouraging, though it’s worth keeping expectations realistic.

Antioxidant supplementation has shown modest improvements in sperm quality and reduced DNA fragmentation in several studies, and adherence to a Mediterranean-style diet has demonstrated favourable effects on semen parameters specifically. Neither functions as a dramatic fix on its own, but as part of a broader set of changes, dietary quality does appear to matter.

A realistic starting point

For anyone looking for practical male fertility tips grounded in actual research rather than general wellness advice, the strongest evidence points toward a specific, manageable set of changes: reducing heat exposure, addressing excess weight if present, cutting smoking and heavy alcohol use, and building a diet with more antioxidant-rich, Mediterranean-style foods. None of these guarantee a specific outcome, but together they represent the areas where the research base is strongest, not just the changes that sound obviously healthy.

Factors worth knowing about, even without strong direct evidence

A few other lifestyle factors come up frequently in discussions of male fertility, with evidence that’s more preliminary but still worth being aware of.

Sleep and stress

Poor sleep quality and chronic psychological stress have both been associated with reduced semen quality in the research literature, though the direct mechanisms are less clearly established than for factors like heat or smoking. Addressing these isn’t a guaranteed fertility fix, but they’re worth attention as part of overall health regardless.

Cycling and prolonged sitting

Intense cycling training and prolonged periods of sitting have both been flagged as potential contributors to testicular heat stress, given the direct pressure and reduced airflow involved. The evidence here is weaker than for hot tub or sauna exposure specifically, but it’s a reasonable factor to moderate for anyone already working to reduce heat exposure broadly.

Mobile phone and electromagnetic exposure

Some research has examined whether carrying phones close to the body affects sperm quality through electromagnetic exposure, though this remains one of the less consistently supported factors in the literature compared with heat, weight, and substance use.

When to see a specialist

If lifestyle changes haven’t led to improvement after several months, or if a couple has been trying to conceive for a year without success (six months if the female partner is over 35), a formal fertility evaluation, including a semen analysis, is a reasonable next step rather than continuing to adjust lifestyle factors indefinitely without a clearer picture of what’s actually happening.

Adam Mulligan, a psychology graduate from the University of Hertfordshire, has a keen interest in the fields of mental health, wellness, and lifestyle.