BMI and Your Balls

A recent study by Dr. Michael Eisenberg revealed that Obese men had a 19 times higher chance of low total sperm count. Learn more about how BMI can impact your chances of conceiving.

BMI and your Balls

We’ve all been there. Staring down a Baconator, cracking open an extra beer during the game, grabbing another donut in the breakroom. Food is awesome. Temptation is everywhere. More and more headlines are talking about the current obesity epidemic (guys, this thing is so widespread it’s getting called an “epidemic”), and we all know that obesity means higher blood pressure, higher risk of heart disease, etc. But what could obesity be doing to your fertility? Can your beer gut be causing your swimmers to go belly up?

Our friend, Dr. Michael Eisenberg, Director of Male Reproductive Medicine and Surgery at Stanford University, says obesity may have a bigger effect on sperm than you think. In his new study, Dr. Eisenberg set out to evaluate how body mass index (BMI) affects fertility, and the results were pretty drastic.

For this study, couples who were trying to conceive were recruited from Michigan and Texas. The couples were comprised of women age 18-44 with regular menstrual cycles and men over 18, in a committed relationship, with no hormonal contraception in the past year and no sterilization procedures. They were interviewed in person, and the men were asked about their lifestyle and their medical and reproductive history. The men then had their measurements taken: height, weight and waist circumference by research nurses. After the measurements were taken, the men were asked to produce a semen sample. These samples were then analyzed for count, volume, motility, etc.

So what about those drastic results? Obese men had a 19 times higher chance of low total sperm count. Meanwhile, our guys with the wider waistlines, those exceeding 37 inches, had a 22% lower total sperm count than their leaner bros. With sperm, the fewer swimmers competing, the less of a chance that anybody wins at all. 22% can mean the difference between baby and no baby.

But why does sperm count take a hit when the pounds start to pile on? Eisenberg says the reason for the relationship between obesity and low sperm count is still uncertain and probably pretty complex. One possible explanation is that excess fat around the abdomen can act as a sort of insulation, raising the temperature of your scrotum. Your body fat could actually be cooking your balls.

So drop the Baconator, leave that extra beer in the fridge and let that donut taunt someone else in the breakroom. Your swimmers will thank you for it.


Eisenberg, M. L., S. Kim, Z. Chen, R. Sundaram, E. F. Schisterman, and G. M. Buck Louis. “The Relationship between Male BMI and Waist Circumference on Semen Quality: Data from the LIFE Study.” Human Reproduction 29.2 (2014): 193-200.

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