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Men need to watch their weight

men-need-to-watch-their-weight-for-the-best-chance-of-fatherhood-mainBeing overweight or obese is an increasing problem in the UK. According to the NHS, 65 per cent of men and 58 per cent of women are classed as being overweight or obese in England alone. Being overweight can lead to a range of health problems, including infertility.

Dr Alasdair Wright explains how extra weight can affect younger men wanting to start a family, and how they can help tackle it.

Focus on fertility

“There has been a lot of attention on obesity as a cause for infertility in women, but only recently has there been a focus on this as a major cause of male infertility,” says Dr Alasdair Wright.

If you think that infertility is more often a problem among women, then it is time to think again. “Male infertility accounts for 40-50 per cent of overall fertility and is due to a decrease in the quality of semen production,” explains Dr Wright.

A number of factors affect sperm quality, such as alcohol, smoking and genetics, and illnesses such as diabetes and hormonal problems. Certain drugs and medications such as anabolic steroids, diuretics and some epilepsy pills can also contribute to the problem.

Excessive prolonged endurance exercise and being underweight can have an adverse effect on male and female fertility but, as Dr Wright explains, obesity is a much more common cause.

Why obesity affects fertility

“It’s known that obesity reduces the levels of the male androgen hormones and increases the levels of oestrogens, which upsets the normal hormone control process which is necessary in the production of healthy sperm.

"Men who are obese can often have problems with reduced libido and erectile function. And the excess fat tissue can increase the temperature around the abdomen and inner thigh areas, which is not ideal for sperm production.”

Your doctor is only likely to make a diagnosis of infertility if you and your wife or partner have been trying for a baby for over a year without success.

However, if you are overweight or obese and want to have a baby, it’s a good idea to start reducing your weight straight away.

What’s your BMI?

One simple way to find out whether you are overweight is by calculating your Body Mass Index (BMI). You can find a BMI healthy weight calculator on a number of internet sites, including NHS Choices.
Just type in your height, weight and age, and the calculator will show your BMI, and indicate whether you are underweight, a healthy weight, overweight or obese. A BMI of between 25 and 29.5 means you are overweight. A BMI of more than 30 means you are obese.  

If you are concerned about your fertility – if you have been trying to conceive for a year, for instance – talk to your doctor. You can also start reducing your weight and improving your health. This can give you a better chance of becoming a father.

Timing is vital

The frequency with which you have sex is important, as this gives the sperm and egg the best chances of meeting. “The most important factor is timing,” explains Dr Wright. “Having intercourse in the fertile window when ovulation might happen is crucial.” Your partner could keep a menstrual cycle diary. You can also buy ovulation kits from most chemists.


“Eat a healthy, balanced diet with plenty of fruit and vegetables,” says Dr Wright. “Weight management is all about calorie balancing, i.e. energy used and energy consumed in foods. The average man needs about 2,500 calories per day.”

For a healthy diet the NHS suggests:

  • Instead of snacking on biscuits, chocolate or crisps, have a piece of fruit.
  • Change sweet fizzy drinks for sparkling or still water.
  • Cut down on foods high in saturated fat, such as butter, sausages and pizza.
  • Choose lean meat, and low-fat spread and ready meals.


Exercise three or four times per week for 30 minutes to one hour or more,” recommends Dr Wright. “Exercise will use up calories and promote more muscle tissue growth. This will indirectly improve your metabolism. Exercise also improves your libido (sex drive).”

Recent research from experts at the Harvard School of Public Health has shown that men who exercised for at least 15 hours a week had a 73 per cent higher sperm count than those who exercised for less than five hours a week.

Health checks

Your GP is likely to carry out a number of health tests. As well as the usual blood pressure and pulse rate tests, your GP may also check your testicles and your penis. They will be looking for any lumps or abnormalities.

They may also carry out a test on your semen. This is to find out if you have a low sperm count, poor sperm mobility or abnormal sperm.


  • Smoking cigarettes. The toxins in tobacco reduce sperm production and quality, which can affect your fertility.
  • Keep your alcohol intake to the recommended 21 units per week with at least two alcohol-free days a week.
  • Try to keep your stress under control. “Long working hours cause mental tiredness which can affect your libido and erectile function."

If you’d like to know more about infertility read our fact sheet or post a question to our online health experts.

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