Diabetes, overweight and underweight people are perilous to their sperm production, showed two reports presented Wednesday at the annual conference of the European Society of Human Reproduction & Embryology, in Barcelona, Spain.

Scientists from University of Aberdeen, Scotland, analyzed the sperm of more than 5000 men in couples facing difficulties regarding having children. On top of other problems (such as smoking cigarettes, excessive alcohol use and age), the heaviest individual had a higher proportion of abnormal sperm than normal-weight men. Obese men had a 60 percent higher likelihood of having a low level of semen and a 40 percent higher chance of having sperm irregularities. Consequently, the researchers affirmed that losing weight improved the quality of sperm and had positive effects on male fertility.

However, experts aren't convinced if that necessarily signifies that heavy men have problems conceiving. "If you have a man who isn't fantastically fertile with a normal partner who is fertile, her fertility will compensate," said Dr. William Ledger, a professor holding classes of obstetrics and gynecology at Britain's University of Sheffield, who was unrelated to the research. But she added that if both partners are obese, that could certainly be a difficulty, since overweight is identified as a factor that reduces women’s fertility.

Scientists insinuated the reason of the bad sperm overweight men have could be too much fat around their testicles, which makes them heat up. So, men all around the world: watch your waistlines! You should to take into account your silhouette when planning a family.