Danish researchers had 56 severely overweight men lose weight. A year later, the number of their sperm had doubled – but only if they maintained their weight.

“It was surprising to us that such a large improvement in semen quality could be shown in association with weight loss,” says study leader Prof. Signe Torekov of the Novo Nordisk Foundation Center for Basic Metabolic Research.

The men were between 18 and 65 years old and competed with a body mass index between 32 and 43. During the eight-week weight loss phase with 800 kilocalories a day, they lost an average of 16.5 kilos.

The success quickly had an impact on sperm counts: During an additional eight weeks of observation, the participants’ sperm concentration increased by 50 percent, and sperm count increased by 40 percent.

For an additional 52 weeks, the men were divided into three groups:

Groups one and three maintained their weight, while group two continued to lose weight. The men in control group four, on the other hand, regained half the weight they had lost.

At the end of the study, men who maintained their weight or continued to lose it had twice as many sperm cells as before their weight loss. “For the men who gained weight again, the improvement was lost again,” explains Torekov.

However, the number of sperm contributes only a part to fertility. The quality of the spermatozoa is also crucial. To assess fertility, researchers also examine how motile sperm are and whether they look healthy.

Given the prevalence of obesity, the study could still make a difference for many people. If overweight men lose weight, their chances of conceiving a child could increase significantly.

In Germany, depending on the source, between seven and 15 percent of couples are unintentionally childless. The reasons for this clearly lie with the man or the woman, with 30 percent each, in 20 percent of the couples both partners contribute, in around 10 percent of the cases the causes are unclear.

Obesity can reduce fertility in both men and women. Compared to men of normal weight, overweight men are 30 percent more likely to have a significantly reduced sperm count.

More than half of the adult population in Germany is overweight or obese, and men are even more affected than women.

The original of this post “Being overweight harms fertility: If you lose weight, you can double your sperm count” comes from NetDoktor.