How Stress Decreases Your Metabolic Efficiency

You’re nailing your fasted training. You’re eating real food, moderating your carbohydrate intake, or even experimenting with LCHF. But you’re still not achieving your ideal body composition. Sound familiar? I thought so.

Here’s why: STRESS.

In a very short physiology lesson, in situations of stress our adrenal glands produce the hormone cortisol. This is part of our “flight or fight” response and is necessary to human optimal function and survival. The role of cortisol is to stimulate the liver to release glucose into the blood, so that in caveman days we were supplied with an immediate source of fuel in order to run away or defend ourselves from the bison/mammoth/bear chasing us. In modern days, where stress is chronic and cortisol levels are therefore consistently elevated, this excess glucose inhibits fat utilization. Read that again.

Longer term, chronic cortisol production overworks the adrenal glands and can end up as adrenal fatigue. This is not to be taken lightly.

Common stressors

Stress doesn’t just include the threat of getting eaten by an animal in the wild. Here is a list of common stressors, that increases cortisol production and therefore need to be considered:

  • Training. Yes, training is a stressor itself. Please check your program is properly periodised, builds appropriately, prioritisies adequate recovery techniques and most importantly, is efficiently personalised. More on this to come.
  • Poor food choices. Cut the gluten, refined sugar and trans fats and just eat real food.
  • Too much caffeine.
  • Restriction. One of the many reasons why calorie counting and starvation are not the answer.
  • Dehydration. Yes, your heart has to work much harder to pump viscous blood around your body and this is a stressor.
  • Lack of sleep.
  • Chemical exposure. Think: air pollution, the cleaning products you use, your beauty regime, BPA in canned products, your toxic takeaway coffee cup lid….
  • Over achieving. Triathletes are often A-type in personality and live by the motto of “more is more”. I’m here to tell you its not. You adapt and get stronger when you’re resting and recovering, not squeezing in an extra session or deviating from your program. And please, stop comparing yourself to others. Your aim is to work out what volume per week, per month, per build, gets you to race day fit, strong and healthy, not stressed, exhausted and on the brink of adrenal fatigue.
  • Work. I don’t think I need to tell you that working in a high pressure job as well as training 15+ hours a week can take its toll.
  • Finances.
  • In 2014, the list just goes on and on….

How do I know if I’m stressed?

The are some strong indicators that you may be considering a “normal” part of endurance training. Waking tired, needing caffeine to get moving, falling asleep or desperately needing a nap at 3.30pm, low libido and poor sleep quality are not normal.

Other signs include carbohydrate cravings, stubborn abdominal fat, poor immune function, gastrointestinal upset and decreased memory and cognition.

Get tested

If this sounds like you, check your salivary cortisol levels with your Nutritionist or Naturopath and monitor this ongoing. Cortisol should be highest in the morning and in line with your circadian rhythm, lowest in the evening before bed. Often those waking exhausted in the morning also get their “second wind” before bed and find their cortisol profile to be almost back-to-front.

I don’t recommend blood tests as you need to test over the course of a day (i.e. 0600, 1200, 1800, 2200) and ideally over multiple days to observe your overall hormonal pattern.

There are also home kits that you purchase online and send off to a lab, but the results still need to be interpreted by your practitioner, so I suggest working with them from day one.

How to reduce stress

Here’s what you need to do:

  1. Choose your fasted training wisely. Fasted training can be stressful and the good news is that you definitely don’t need to complete every session or even every morning session fasted to improve fat adaption. Three to four sessions per week is adequate and if you are just getting started, 60-90 minutes in duration is sufficient. As your fat adaption increases you can extend the duration, but please monitor recovery, sleep quality, subsequent performance and your immune response before your push the boundaries too far.
  2. Add branched chain amino acids (BCAAs). Ideal to pop in your water bottle for fasted sessions to prevent muscle breakdown (catabolism).
  3. Choose good carbohydrates (such as starchy vegetables) for recovery and periods of high intensity. Restriction is stressful and extremely unnecessarily.
  4. Cut or significantly reduce the coffee. I’m sorry.
  5. Monitor your protein intake at night. Protein increases cortisol, so keep your dinner to a palm size serve of meat, fish or chicken to allow your levels to match your circadian rhythm.
  6. Go to bed early. 7.5 hours sleep is a great aim to recharge and wake refreshed.
  7. Supplement. Please work with your Nutritionist or Naturopath here, but research shows omega 3, B vitamins and magnesium are beneficial in times of stress.
  8. Meditate. 10 minutes per day has been proven to make a difference to your stress response and I know you’ve heard it before, so isn’t it time you made it a priority?

Does this resonate with you? Share your experience below.

Image credit here.


  1. Renee Fiedler

    This blog post is perfect timing for me. My husband and I have always eaten rather well, but used to follow more of a low fat approach. We have changed our eating style and take a more LCHF approach now but I have gained about 4 kilos (all around my stomach and bum) and my husband has also put on weight. My husband would be a high candidate for adrenaline fatigue, but myself not so much. I exercise regularly with a combination of yoga, strength training, and interval running. It is disheartning not see much progress.

  2. ian rambo

    I know there are others like Almonds, Spinach and Pumpkin seeds but Expresso coffee is a good source of Magnesium. Surely a bulletproof coffee first thing in the morning harms no one.?  Good info though, thanks Steph. I actual settle my nighttime adrenalin spikes with a few pieces of salty dark chocolate, helps with the accasional calves cramps too.

    Sent from my iPad

  3. Tom

    Excellent article and very practical advise that we all know but should follow

  4. Steph

    One to two coffees a day is fine – it’s a dose dependent consideration. Thanks for your input Ian.

  5. Keith

    Any recommendations on the type/brand of BCAA’s and the dosage? Would dosage depend on the length of activity?

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