You don't need a doctor to perform a vasectomy anymore -- Little Debbie can do the job for you, and she doesn't even have a medical degree.

Short of repeated blows to the groin, a diet rich in junk food is just about the worst thing you could do for your own fertility, and new studies prove again that men who eat the most junk have the most problems with their sperm.

In fact, a diet rich in trans fats -- the dangerous man-made fat that comes from vegetable oils -- can KILL up to 40 percent of your sperm, according to data presented at a recent meeting of the American Society for Reproductive Medicine.

"So what," you're thinking. "That leaves plenty of sperm left, and all it takes is one to fertilize an egg."

Not in this case -- because another new study finds that men who eat the most junk food have lazy do-nothing sperm lacking in "motility," a primary indicator of fertility that basically means the ability to hunt for an egg.

No motility = no baby -- no matter how many sperm you're firing off.

If you're looking to avoid trans fats -- and you should, even if you're well past the point of caring about your own fertility -- don't trust anything you read on the food labels.

They lie -- and they lie with the government's blessing, because the feds allow them to round "small" amounts of trans fats down to zero.

Like everything else, "zero" just ain't what it used to be.

Just look at the ingredients instead: If you see hydrogenated oils of any kind, assume there's trans fat inside... because there almost certainly is.