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  • Shayna Schmidt

Hormones & Exercise-- How are they Related?

A lot of our clients, particularly our female clients, don't realize how much hormones come into play when en route to achieving health and fitness goals.

The law of thermodynamics is typically what trainers discuss when guiding a client on a weight loss journey: if you expend more energy than you take in, you'll lose weight. Calories in versus calories out. However, many times that "fool-proof" system fails, and actually in our opinion some of the best trainers are straying from that coaching system these days. There are simply so many other factors at play that it's really not that simple. So let's talk about one of those factors: hormones.

There are five hormones that will inevitably affect the success of your fitness results: irisin, cortisol, insulin, thyroid, and testosterone (men)/ progesterone (women). When in balance, these hormones have the largest effect on your metabolism. When out of balance, they can be the reason you're not achieving results. I’m not a hormone expert, so to help me fill the gaps in my knowledge for the sake of this article, I contacted an actual expert: my dear friend Michelle Aspinwall. She is an incredible hormone health coach and she had a lot to say. Here’s our breakdown of the five hormones and how they are each affected by exercise.


Irisin, often referred to as the exercise hormone, torches fat in two ways. First, it activates genes that transform calorie-storing white fat cells into good brown fat cells, which continue to burn energy after you finish exercising. Second, it appears to inhibit the formation of fatty tissue. Added bonus: it may also protect brain cells from injury and aging.

How exercise affects it: Getting sweaty stimulates your body's irisin production. Studies have found that both moderate intensity exercise and HIIT can raise levels of irisin for up to 12% (still think females shouldn't be lifting heavy?!). You'll get an irisin boost by working up even a small sweat, but one of the best ways to turn on irisin is by intermittent fasting (future post on this topic coming soon) and following up that fast with moderate or high-intensity training.


Our adrenal glands produce cortisol in response to stress. Mental stress, emotional stress, physical stress, and environmental stress are all forms of stress that cause your body to increase cortisol production. When cortisol levels increase, this stimulates the sympathetic nervous system, aka your "fight or flight" response. This activation tells your body that you’re in danger and it immediately increases your blood pressure, elevates your heart rate, and your liver releases glucose into your bloodstream. If this happens for an extended period, it will start to affect other hormones and wreak havoc on your metabolism. People under stress (aka all people) generally have excess cortisol circulating, which increases abdominal fat and generally creates an internal environment that doesn't allow for weight loss.

Michelle adds, “Women especially should manage their blood sugar like their life depends on it. High cortisol prematurely ages us, and both high and low cortisol causes our bodies to suffer through digestion, sex drive, energy, and coping with emotion and mood. Having tools to cope with stress like exercise, nutrition and meditation are all important aspects to maintaining hormonal balance.”

How exercise affects it: If you attempt a high intensity workout when your cortisol levels are already elevated above healthy ranges, it can add more stress to your already stressed system. Lower-intensity exercises may be the best recommendation for people in a state of chronic stress.


The pancreas produces Insulin in response to elevated glucose levels in the blood. In small doses, insulin is very anabolic (phase of metabolism when complex molecules are built up), but when insulin is secreted over long periods of time, the metabolism does some interesting things.

First, since your muscles are not getting fed, they tell the brain that you're hungry, and particularly hungry for sugar since that will bring energy levels up the quickest. Next, it increases inflammation systematically, which then increases cortisol. Lastly, when glucose levels rise, your body tries really hard to do anything it can to lower it, shifting the fuel utilization away from fat-burning to carb-burning... not something we want.

How exercise affects it: Since insulin balance and blood glucose regulation go hand-in-hand, and elevated blood glucose has been shown to slow down fat utilization, maintaining a healthy insulin balance is important for the metabolism. HIIT workouts have been shown to improve insulin sensitivity. However, if cortisol is suspected as being elevated, HIIT can also increase cortisol (as mentioned earlier), worsening insulin resistance. A proper balance of 1-2 HIIT sessions per week combined with lower-intensity and active recovery activities is a good way to start to positively affect insulin sensitivity.


The thyroid hormone is the main metabolic hormone in the body. The thyroid gland (location: throat) produces an initial hormone (T4), which is actually metabolically inactive; it must be converted into T3 in order to affect your metabolism. Going back to earlier-- another problem with elevated cortisol is that it can inhibit this conversion. When you have hypothyroidism, or an underactive thyroid, your metabolism slows, causing you to gain weight more easily as well as feel sluggish and fatigued.

Just like stress affects cortisol (and all hormones… and everything, really), it definitely affects thyroid function. Perhaps you have heard of the HPA (hypothalamic-pituitary-adrenal) axis, which is a complex network of interactions between the hypothalamus, the pituitary, and the adrenal glands that regulates things such as temperature, digestion, immune system, mood, sexuality, and energy usage-- in addition to controlling the body’s reaction to stress and trauma. Countless studies show that chronic adrenal stress depresses hypothalamic and pituitary function. And since these two organs direct thyroid hormone production, anything that disrupts the HPA axis will also suppress thyroid function. Michelle further emphasizes that “thyroid imbalance and this axis are intimately linked,” and she advises her clients to evaluate the following three areas of their life to see if improvements are desired:

  • PMS symptoms: “usually lessened if B vitamin levels are in check”

  • Stress levels: “look at sleep and exercise”

  • Fatigue or overdrive: “especially as they apply to your relationships and your enjoyment or frequency of sex.” Well, that sounds important, eh?!

How exercise affects it: Exercise intensity, especially in terms of cardio, has a profound effect on thyroid hormones. A study on exercise intensity and thyroid hormone levels found that at anaerobic threshold (approx 70% of maximum heart rate), all thyroid hormones were improved from baseline. But high stress in general can cause symptoms of hypothyroidism, and the physical stress caused by intense exercise is no exception. Also, P.S., there is a possibility that super low carb diets suppress thyroid function (see Paul Jaminet's blog post here). So if you're regularly doing HIIT and want to avoid symptoms of overtraining stress, don't skimp on the carbs.

Michelle adds, “One way to help energy levels during intense cardio sessions is to add some clean collagen powder to your water. This is high in amino acids leucine, isoleucine and valine which help not only fuel muscles but also maintain healthy connective tissue.” Michelle and I both recommend Vital Protein Collagen Powder (neither of us are affiliated with this brand, just love it!), specifically because they responsibly source their collagen from pasture raised cows.

Sex Hormones

Testosterone and progesterone are the two main hormones in males and females, respectively. In males, if testosterone levels fall, it causes a loss of energy, limited ability to build and maintain muscle mass, and a loss in libido. In women, lowered progesterone production causes an imbalance in the estrogen to progesterone ratio, resulting in irregular menstrual cycles, an increased risk for PCOS, pre-menopausal symptoms, and an increase of fat storage around the hips and triceps.

Interestingly enough, elevated cortisol (i.e. chronic stress) can lower both testosterone and progesterone production through something called "pregnenolone steal." In addition, there are several other factors that cause lowered sex hormones, including pesticides and nutrient deficiencies.

How exercise affects them: High intensity resistance training has been shown to have the most beneficial effect on testosterone in men, and cardio training and resistance training at a moderate intensity has shown similar results on the sex hormones in women.

We mostly focus on external factors of health like exercise and nutrition when it comes to a weight loss goal. But the internal factors, hormones included, have a huge say in whether you nail those inches off your waist, or see some ab definition, or build those quads. We hope the highlighting of these five hormones have helped you get a better grip on what else is out there that has a powerful influence over your health, and what you can do to control it. You most likely hear this one ALL the time, but Michelle and I both recommend staying hydrated consistently as well as eating a high-fiber diet to help the body’s natural detoxifying processes to eliminate used and unwanted hormones. Happy exercising!

A note from Michelle about her Supported Intermittent Fasting Program:

“My IF program has launched, I have 10 spots and it’s a group program! I have priced it very reasonably at $47 for 17 days of support. This includes: 2 weeks of meal planning with shopping lists, 3 group coaching calls and access to my private Facebook group just for this program. I will be quite active for the 17 days answering questions, guiding and providing some accountability. My hope is to run this program a few times a year.” Check it out via the link above!

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