Are your swimmers paddling up to par? There’s no easy way to gauge the quality of your semen just by looking at it, so you’ll need to schedule an appointment with your doc to find out for sure. But while you wait, here are scientific signs that suggest you’ve got strong sperm. How many can you cross off?
1. You Sculpt a Lean Midsection
Actually, you don’t even have to boast a six-pack—as long as you don’t have a gut, your semen is probably in tip-top shape. Researchers from the Netherlands found that men with a waist circumference of 40 inches or greater had lower sperm concentrations and counts of normal-moving sperm than guys with a more whittled waist.
The researchers aren’t exactly sure why a spare tire is bad for your swimmers. But they believe carrying too much weight—especially around your midsection—may interfere with the release of sex hormones, as well as the production and development of sperm.
2. You Don’t Look Like Don Draper
Good news, average-looking guys! Having a masculine mug might actually hurt you down below the belt, according to a new study. Spanish and Finnish researchers recently discovered that men who had faces that were rated as manly—i.e. wider and broader—tended to have poorer semen quality than more feminine-faced guys.
One possible reason: a theoretical explanation called the “tradeoff hypothesis.” Simply put, men have a fixed amount of energy available to devote to reproductive resources. And that energy must be distributed to a number of different components. “So, if a male consumes more resources on semen production, he may have fewer resources available for developing attractive secondary sexual traits, like facial masculinity,” says study author Jukka Kekäläinen, Ph.D.
3. You’re a Fish Man
Quick, think of your favorite go-to protein: is it red, salty, and processed? If so, your semen might be paying the price.
Harvard University researchers found that men who ate the most processed meat had significantly lower counts of normal-shaped sperm compared to those who consumed the lowest. Fish, on the other hand, seemed to have a protective effect. Guys who ate the most fish—especially dark-meat kinds like salmon and tuna—had a 65 percent greater sperm concentration than those who ate the least.
Credit fish’s omega-3s, since long-chain polyunsaturated fatty acids play a part in sperm production, the researchers say. So if you’re looking to strengthen your swimmers, sub out your pepperoni topping for some anchovies.
4. You Scorn the Tighty Whities
Here’s another reason briefs might feel a bit on the constricting side: they could be suffocating your sperm, too. A 2012 study from the U.K. found that men who wore boxer shorts instead of tight-fitting underwear were 24 percent less likely to have a low-motile sperm count. Motility, or how sperm swims, is important, because sluggish sperm can have difficulty reaching the egg to successfully fertilize it.
“Loose-fitting underwear may result in lower scrotal temperatures compared to tight-fitting underwear, hence an improvement in semen quality,” says study author Andrew Povey, Ph.D. There’s also evidence that elevated testicular temperatures may hinder sperm production, he says. So if you want to be on the safe side, let your junk breathe.