Looking to bulk up? Breast milk is the latest trend in weightlifting

You've heard breast milk is best for babies. Now, some bodybuilders believe it also has benefits for adults when it comes to adding muscle.

"You hear everything: testosterone, gorilla hormones. People are willing to go overboard on just trying to be bigger and be better," Crossfitter Austin Mariglia told ABC affiliate WZZM-TV.

"I would never in my wildest dreams think somebody would be drinking breast milk for performance," Crossfitter Jake Platt told ABC affiliate KOMO-TV.

There are many others, however, who are convinced milk from a human is better for your muscles than milk from a cow. An online search uncovered dozens of online forums and articles that spotlight this growing trend. Many of those sites are filled with classified ads for "men buying breast milk."

But don't expect to hear these guys talk about drinking breast milk while pumping iron. Women who sell their milk say most of their male buyers perfer to stay anonymous.

"They usually first ask if there's anymore milk available," breast milk seller Jennifer Rose told KOMO-TV. "I just find that they're very secretive. Even when they call me their numbers are blocked. They just don't want to be seen or known."

Tap here to watch KOMO-TV's report.

Some online breast milk banks are paying women up to $1,200 a month for selling extra breast milk, WZZM-TV reports. It's a trend that worries pediatricians.

"I would discourage anyone from purchasing breast milk from those untrusted sources," said Dr. Lana Gagin. "The way this milk is stored and processed is not always safe."

Gagin also doesn't believe all the hype surrounding breast milk and bigger muscles.

"There is nothing in breast milk that can be of benefit to a healthy adult or there is nothing in breast milk that would enhance your physical performance," said Dr. Gagin.

Registered nurse Emily Pease agrees. She tells KOMO-TV that that breast milk isn't "harmful" to adults, but "there is no evidence that (she's) aware of that demonstrates the benefits of adults consuming human milk."

WZZM-TV crunched the numbers:

• In one cup of breast milk:
• 2.5 grams of protein
• 10.8 grams of fat
• 17 grams of carbs
• 172 calories
• One cup of cow's milk:
• 7.9 grams of protein
• 7.9 grams of fat
• 11 grams of carbs
• 146 calories

Breast milk does have nutritional benefits for babies and can even help fight against diseases.

A check of online sites shows breast milk currently sells for anywhere from $2 to $5 an ounce.