A great deal is written about lifestyle and fertility, much of it overstated. Here is a straightforward account of what the evidence actually supports — and what is not worth losing sleep over.

One point first: this applies to both partners. Male factors contribute to around half of fertility problems, and sperm quality responds to lifestyle change at least as readily as ovulation does.

Weight matters most

Of all the lifestyle factors, weight has the clearest effect.

In women, being significantly overweight or underweight can disrupt the hormones that drive ovulation, causing irregular or absent cycles. Where excess weight is the cause, even a modest sustained loss can restore ovulation without any medication.

In men, obesity affects hormone levels and reduces sperm count and quality.

The aim is steady, sustainable change rather than crash dieting, which can itself disrupt cycles.

Diet: sensible, not special

There is no fertility diet, and no food that will make you conceive. What helps is an ordinary balanced diet: vegetables and fruit, whole grains rather than heavily refined ones, pulses, fish, and moderate portions.

Folic acid is the one supplement that genuinely matters, and it should start about three months before you try — not once you are pregnant. See our guide to preconception care for the doses used here.

Diets very high in trans fats and heavily refined carbohydrates have been associated with poorer fertility, though the effect is modest compared with weight itself.

Smoking

This is the clearest harm after weight. Smoking is associated with reduced fertility in women and with lower sperm count, motility and quality in men. Studies have found women who smoke are meaningfully more likely to experience fertility problems than non-smokers, and smoking also brings forward the age of menopause.

Passive smoking matters too. The effects of e-cigarettes on fertility are not yet well established, which is a reason for caution rather than reassurance.

Stopping helps, and it helps reasonably quickly.

Alcohol

Heavy drinking clearly reduces fertility in both partners. Regular moderate drinking has been associated with taking longer to conceive. An occasional drink is unlikely to be the reason a couple is not conceiving, but cutting down is sensible while trying — and once pregnant, the advice is to avoid alcohol altogether.

Caffeine

Moderate caffeine — around two to three cups of coffee or tea a day — has not been shown to reduce fertility. Very high intakes have been associated with longer time to conceive. There is no need to give it up, but there is no benefit in large amounts either.

Exercise

Regular moderate exercise supports fertility, mainly through its effect on weight and general health. Walking, swimming and similar activity are ideal.

Very intense, high-volume exercise can suppress ovulation, particularly when combined with low body weight. If your periods have become irregular or stopped since increasing your training, that is worth discussing with a doctor.

For men specifically

  • Keep the testicles cool — avoid prolonged hot baths and saunas, very tight underwear, and long unbroken periods sitting
  • Avoid anabolic steroids entirely — they can stop sperm production altogether, sometimes persisting long after stopping
  • Avoid recreational drugs

Because sperm take about three months to develop, changes made today show up in a test roughly three months later. It is worth knowing this so the wait does not feel like failure.

Stress

Severe stress can disrupt cycles. But it is worth being careful here: telling couples to “just relax” is unhelpful, and often adds guilt to an already difficult situation. Stress is not usually the cause of infertility, and difficulty conceiving is itself stressful — the arrow points both ways. Look after your wellbeing because it matters, not because relaxing is a treatment.

What is not worth worrying about

Position after sex, lying down afterwards, specific “fertility foods”, and most supplements marketed for conception have little or no evidence behind them. If money and effort are limited, spend them on weight, smoking and alcohol — that is where the returns are.

When to seek help

Lifestyle changes are worth making, but they are not a reason to delay assessment. See a doctor after a year of trying, or six months if the woman is over 35 — sooner if periods are irregular or absent, or if either partner has a known relevant condition.

The bottom line

Weight, smoking and alcohol are where lifestyle genuinely affects fertility — for both partners. A normal balanced diet plus folic acid is enough; there is no special fertility diet. Make the changes that matter, ignore most of the rest, and do not let lifestyle changes delay getting assessed.

References

  1. National Health Service. Infertility — prevention [Internet]. NHS; [cited 2026 Jul 22]. Available from: https://www.nhs.uk/conditions/infertility/
  2. National Institute for Health and Care Excellence. Fertility problems: assessment and treatment. NG257. London: NICE; 2026. Available from: https://www.nice.org.uk/guidance/ng257
  3. National Health Service. Planning your pregnancy [Internet]. NHS; [cited 2026 Jul 22]. Available from: https://www.nhs.uk/pregnancy/trying-for-a-baby/planning-your-pregnancy/