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Cortisol and Testosterone

Or: “Embracing My Inner Cat”.

“It’s cliche to see a kitty playing with a ball of yarn, but it’s cliche for a reason. A ball of yarn is fun, it’s something humans have never figured out. Humans never saw the beauty in a ball of yarn, they tried to make it into things, sweaters, blankets, but the cat knew all along that it was good as it was.” – Home Movies

Why do cortisol and testosterone matter? Along with growth hormone, they are the two most important hormones that affect your body’s response to nutrition and exercise. In the right ratio, they can confer energy, virility, and slow the aging process. In the wrong ratio, it’s heart attack city. Growth hormone has gotten a lot of press recently because as a supplement, it may be safer and have fewer side effects than anabolic steroids. GH mobilizes fat stores and glycogen (starch) stores to encourage production of amino acids (which means more muscle). Testosterone has pretty much the same effect. Cortisol, on the other hand, breaks down protein (and everything else) to spike blood sugars, which in turn stimulates insulin to turn some of that sugar into glycerol (the backbone for fat storage).

What happens after your workout? Cortisol and testosterone increase linearly as your workout continues (at intensity levels greater than about 60%). 10K runs, or half-marathons? The perfect scenario for sky-high cortisol levels. The longer you go, the higher your cortisol level gets. But testosterone has a peak, somewhere between 10-60 minutes. Weight-training (of any sort) and high-intensity short-burst exercise spike testosterone levels. So the best answer for how to acutely. This study showed that even “chronic cardio” exercise of >60-90 minutes can increase free (available) testosterone a little bit, but cortisol levels were through the roof at the end.

But we’re also in it for the long haul. So what keeps long-term cortisol levels low and testosterone levels high? Sleep, obviously. And eating a good diet. What does “good” mean? Well, this study looked at healthy men with weightlifting experience who did a solid weight-training workout once a week for 3 weeks. The lifts did their job. Significant increases in testosterone with minimal change in cortisol levels. Their nutritional profiles dictated their levels of ‘pre-workout’ testosterone over time, and the results may not be what you expect:

Percentage of fat calories in the diet had the greatest correlation to increased serum testosterone levels at a baseline in the subjects. And breaking it down even more, it was the amount of monounsaturated and saturated fat in the diet that built the linear relationship to elevated testosterone. A high percentage of protein in the diet *decreased* testosterone, even more than a high percentage of carbs. In fact, a carb:protein ratio of 4:1 was associated with the highest testosterone levels. Take these figured with a grain of salt: nobody had more than 30% fat in the diet, nobody ate even half as many protein calories as carb calories, and the average diet was super high-carb: 2475 cals (120g P (20%) / 63g F (23%) / 346g C (56%)).

Take from that what you will, and perhaps a low-carb diet has a more positive effect on testosterone levels in general, but it’s certainly an encouragement to keep protein intake from getting too out-of-control, and it’s a ringing endorsement for the power of good fats. Much like the Perfect Health Diet, which I have been tinkering with this month, as well as the dreaded re-introduction of breakfast. It’s been a week, and while I haven’t been the cleanest with my diet (averaged about a drink a day this week, as opposed to 3-4 per week in the average week), I do feel a little fuller. My weight’s a steady 182 lbs, and my strength has been getting better, but some of the muscle definition I had last month seems to be fading. Maybe I need to listen to my girlfriend, embrace my inner cat, and take some afternoon naps.

Next time: it’s a ‘deloading’ week from heavy lifting on the Wendler program, so I turn it into speed week. Lots of hills, lots of burpees, hopefully no vomiting.



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