Low-carb diets, cortisol & testosterone
* A systematic review (look at all evidence) and meta-analysis (pool it together to see the overall effect) has been published reviewing the effect of low-carb diets on cortisol and testosterone in young, healthy, active, men.
* As a general principle, findings of higher cortisol and/or lower testosterone, resulting from a diet, would be seen as bad outcomes.
* The review examined 27 studies involving 309 men with an average age of 27.
* Various permutations of resting and post-exercise, cortisol and testosterone, exercise duration and whether the low-carb diet was high or moderate protein were examined in separate sub-groups.
* Half the sub-group analyses did not achieve significant results; the other half did. Non-findings are important as well as findings.
* The most important non-findings were that nothing significant was found – for either cortisol or testosterone – in diets lasting longer than three weeks.
* The most important findings were that low-carb diets resulted in higher cortisol after exercise lasting 20 minutes or longer. This may have been the result of gluconeogenesis. Also, high-protein low-carb diets decreased resting testosterone, but moderate-protein low-carb diets didn't, so don't blame the low carb for what the high protein did.
* This was a thorough and impressive study with some interesting findings. Anyone following a low-carb diet for longer than three weeks should not be concerned by the results.
The rest of this article is available to site members, who get access to all articles plus a weekly newsletter.
To continue reading, please login below or sign up for a membership. Thank you.