It’s official, and it’s officially bizarre. Multiple studies are finding whey protein shakes cause testosterone to drop like a lead balloon.
The advice to "get plenty of protein" is one of the ten commandments of muscle-building, with whey commonly recommended as the perfect source.
However, research studies are repeatedly noting that testosterone, the anabolic hormone directly responsible for muscle-building, starts taking a dive within minutes of consuming the very same whey protein shakes we use to try to build muscle.
Studies show consistent, significant decreases of 10% or more in testosterone.
Needless to say, these anti-protein studies have sparked a fierce debate throughout the lifting community and left us feeling like:
Yet another research team reached the same conclusion just last month and published their findings in the Journal of Clinical Endocrinology (Clinical trial registration: NCT03412136).
Can it really be? Have we all been so wrong about post-workout protein?
Don’t give up on your post-workout shakes just yet.
The sudden reduction in measurable testosterone isn’t bad – it’s just misunderstood.
In fact, while counter-intuitive, these studies are proof that protein shakes do work.
So just what in the seven hells is going on?
During weight training, testosterone levels spike in your blood stream. This muscle-building hormonal goodness gets circulated throughout the body, with a special emphasis on any muscle groups that have a particularly good pump.
Then, post-workout, we slam down 25-40 grams of quality protein and testosterone disappears faster than a toupee in a tornado.
But all is not lost.
What’s happening is that the amino acids in the protein have signaled muscle cells to open their androgen receptors – imagine little mouths on every muscle cell that can only eat testosterone and other anabolic hormones.
The amino acids in protein (especially whey protein) tell these muscle cell receptors to open wide for a big ol’ gulp of testosterone.
Here’s a nerdy, but helpful, graphic of the process at work:
When testosterone appears to vanish after ingesting protein, what’s really happening is that muscle cells are soaking up all the testosterone they can get.
This temporarily lowers the detectable level of testosterone in the blood stream.
Once the entire process is examined, it makes perfect sense.
We’re not spiking testosterone levels up and then circulating it just to watch it go round n’ round the bloodstream. The goal all along has been to use the bloodstream to drive it to where it needs to go.
Protein does indeed cause blood testosterone levels to appear to drop, but it’s nothing to worry about.
The whey protein in the shake is triggering muscle to draw testosterone out of the bloodstream and put it to good use.
So lift heavy, train hard, and raise a glass of post-workout protein. Here’s to your gains.