T Nation

High Protein=Low T?


I'm studying for a PT certification and the literature states that a diet high in protein has been associated with low T levels. They reference this study from 1997:

Testosterone and cortisol in relationship to dietary nutrients and resistance exercise

found here:


Is this information outdated? Is it correct? Are we compromising our T levels with high protein diets?

Any help with this is appreciated.



bump for this


Interesting study. I think that more information is needed to come to any real conclusions.

For example, and I have no idea that this is the case, but perhaps higher protein consumption leads to more muscle building/rebuilding which "consumes" more T, leading to lower resting levels.

Without knowing a little more it is hard to say whether or not this might be something to be concerned about.

However, as has been told to us many times, cutting out fats may not be very beneficial to us -- and this study does agree with that anyway.

Maybe somebody with more expertise could comment -- or you might ask Dave Barr during the next Prime Time, see what he thinks of the study?



I was also thinking that more info was needed, until I read that what they found had agreed with a few prior studies.

Interesting take on the muscle building consuming T.

Either way, since this study is almost 10 years old, I'm sure some one here can shoot it down, or we wouldn't be seeing high protein diets recommended.


did y'all actually read this study?

while it said that diets with 44% or higher amounts of energy derived from protein showed a lowered serum T, it also went on to say that people who consumed animal based proteins had higher T than those consuming vegetable based proteins, and they also thought that the protein-carb ratio had a LARGE part to do with the lowered T in people.

It also seemed like the FOCUS of this study was to show that dietary fat is directly assosciated with T levels in athletic males. More fat, more T. More SFA and MUFA, more T!

moral of the story: EAT MEAT and ditch the vegetable protein (like soy, which was probably used), and have a higher T level.


Yeah-higher protein equaling lower T would seem to go against most of what I've heard and read. Maybe when lowfat, and fat free protein and carbs crowds out necessary fat, low T results. This would make sense. There's a lot of evidence that low fat diets lead to low testosterone. The body needs an appropriate amount of fat, including some saturated, for nomral hormone levels, including testosterone.


Yup thats the prob. The study shorts the participants in other macros. You still need carbs and fats in the right amounts to go with the High Protein to get the biggest bang for the buck.

If you short on any macro to a certain extent you will short yourself and all bodily functions.


Least thats my lil thought.


vroom may also be onto something with the "enhanced uptake" theory.

The same research group has shown lower T following resistance exercise when PWO meals are consumed. They reason that it's simply "entering muscle cells" and leaving the blood.



smallnomore, that is a skewed view of science. Why would we try to shoot it down? Wouldn't it be better to adjust our thnking based on all of the available data?

For example, let's say that high protein intake drops T in a bad way. We also know that we need a little more dietary protein for muscle growth. Rather than calling one of these concepts "wrong" we could conclude that the reduction in T won't affect muscle growth.

Besides, consuming protein is directly anticatabolic and often anabolic, so who cares what happens to our T levels.

I'll go into this more in the Anabolic Index Article.



Bad choice of words on my part. When I said shoot it down, I meant explain why with this evidence, high protein diets are still a good/great idea.

Really, I'm trying to figure out why the Apex Corporation (whose cert. I have to get to make more money) states to stay away from high protein diets, period.

Aside from that. I believe they tested T levels before exercise. Is it possible that the muscle building process would inhibit T throughout the day, or is their method of testing only seeing a small picture of fluctuating T levels?

If this will all be covered in the article, I'll wait patiently.

By the way, thanks for chiming in!


They're probably still on the too-much protein will make your kidneys explode bandwagon. Maybe they have the soy lobby influencing them.


OR maybe it's because two out of the first three ingredients on their meal replacement bars are corn syrup and high fructose corn syrup, so they need to convince people to suck down simple carbs. haha