Is fat damaging sperm?

Overweight men risk chances of infertility

If you’re worried about the effect scoffing too many fatty foods will have on your waistline, you need to start thinking about what’s happening a little more below the belt. Smoking and heavy drinking have already been named as factors affecting fertility, now excess weight has been added to the list.

According research by the University of Aberdeen in Scotland, obese men have worse sperm than those within their recommend weight bracket. Scientists examined sperm of over 5,000 men in Scotland, splitting the samples into two groups depending on the subject's BMI. Men who had an optimal reading of between 20 and 25 had a higher count of normal sperm.

Those who fell into the overweight group on the other hand were found to have a 60 per cent higher probability of producing a low amount of semen and a 40 per cent higher chance of those sperm being abnormal.

There are a number of theories as to why overweight men have problematic sperm. Primarily it’s thought that because fatty tissue influences the metabolism of sex hormones, in abundance, it may damage the production process. Temperature could also be a factor. Sperm is in its optimum production environment at two degrees cooler than the normal body temperature. As obese men have more fat, it stands to reason they are more likely to get overheated.

So what does this actually mean? Experts cannot confirm if this means all obese men will face difficulties having children. If you are overweight and your partner is fertile and a regular weight, her fertility should, in theory, compensate. However Dr William Ledger, a professor of obstetrics and gynecology at the University of Sheffield, points out that if both the man and women are overweight, this will present a problem.

According to Dr Ghiayath Shayeb, who led the research, losing weight is the first step for overweight men who want to improve their chances of conceiving. "Our findings were quite independent of any other factors and seem to suggest that men who are trying for a baby with their partners should first try to achieve an ideal body weight."

It makes sense: – the healthier you are, the healthier your sperm will be. Male fertility expert Dr Thomas Walsh from US San Francisco in the US agrees, saying, "If your goal is to family plan, your job is to be the healthiest person you can be."