Let’s talk about something sneaky. You’re eating better. Maybe even moving more. But the scale won’t budge, your belly feels bloated, and you’re exhausted. Sound familiar? If so, it’s time to talk about cortisol, the stress hormone that quietly wreaks havoc on your appetite, energy, and mood, often leading to stubborn weight, poor sleep, and hormonal chaos.
In this third part of our hormone series, we’re diving into the world of cortisol. A hormone designed to help us survive real danger, but one that now gets triggered by emails, traffic, sleepless nights, and that third coffee. When it’s constantly dialled up, it can make your body feel like it’s stuck in survival mode, even when there’s no real threat.
What Is Cortisol, and Why Does It Matter?
Cortisol is a steroid hormone produced by your adrenal glands, which sit on top of your kidneys (not in your brain, as many people assume). If you examine a diagram of your kidneys, the adrenal glands appear as two small hats perched on top of the kidneys. This is part of our endocrine system (hormones) and also part of our stress response system. This fast-acting hormone keeps you safe in times of danger by releasing sugar into your bloodstream, raising blood pressure and sharpening your senses. Ultimately, it has a very important role, but it is not without its issues.
In times of physical or emotional stress, cortisol levels rise, increasing blood sugar, raising blood pressure, and flooding the body with energy to respond to a perceived threat. Back in caveman days, it helped us run away from wild animals. These days, it’s more likely to be triggered by deadlines, arguments, poor sleep, or scrolling the news at midnight. The trouble is that modern stress is rarely short-lived. And long-term activation of this stress response takes its toll.
These days, our stressors look more like:
- Work deadlines
- Lack of sleep
- Financial worries
- Parenting burnout
- Chronic illness
- Too much caffeine, sugar, or alcohol
Unlike a short burst of stress, these modern pressures are constant. And chronically elevated cortisol keeps your body locked in “survival mode”. We no longer run away and expel the energy produced. Often, we experience these ‘stresses’ while sitting on the sofa, driving a car, or at our desks.
Cortisol – Weight Gain Connection.
Cortisol tells your body to release more glucose into the bloodstream (gluconeogenesis) so you have energy to fight or flee. But if you’re not using this energy through physical movement (and let’s face it, most of us aren’t), it gets stored, often as visceral fat around the abdomen.
It also:
- Increases cravings for sugary, carb-rich comfort food
- Reduces insulin sensitivity, contributing to insulin resistance
- Disrupts leptin, so you don’t feel full
- Triggers ghrelin, making you feel hungrier
- Suppresses thyroid hormones, slowing metabolism
In other words, cortisol is like an overzealous bodyguard that means well but keeps misfiring. So, even if you’re eating well and exercising, you might find progress stalling if cortisol is high. And let’s not forget how quickly one bad night’s sleep or a stressful week can throw everything off.
When Cortisol Crashes: Burnout in Disguise
High cortisol is only part of the story. When your system has been on high alert for too long, it can tip the other way, leading to low cortisol production. This is commonly mislabelled as “adrenal fatigue”, but more accurately, it’s a sign that your brain and adrenal system are no longer communicating well.
Symptoms of low cortisol include:
- Fatigue
- Brain fog, feeling foggy or detached
- Salt or sugar cravings
- Feeling worse after exercise
- Low blood pressure or dizziness when standing
- Low mood, anxiety or emotional flatness
- Weight gain, especially around the belly.
- Poor sleep, even when exhausted.
It’s a sign your system is no longer coping. You may look fine from the outside, but feel like the spark’s gone. It’s your body’s way of saying, “I’m done.”
Cortisol and the Circadian Rhythm
Your cortisol should follow a natural daily pattern:
- High in the morning to wake you up and energise you
- Steady decline throughout the day
- Low in the evening so melatonin can rise for restful sleep
Excessive exposure to blue light at night, irregular sleep patterns, or stress can disrupt this, leading to nighttime alertness, poor sleep, and morning grogginess.
This daily pattern is known as your circadian rhythm, and it’s crucial for everything from energy levels to hormone regulation. Within that rhythm is something called the Cortisol Awakening Response (CAR), a natural 200% spike in cortisol that occurs within 30 minutes of waking. Think of it as your get-up-and-go (but it also offers many other excellent health benefits), and for many of us, it has gone up and gone. For many of us, CAR is either missing entirely or continues beyond the usual window, especially after long-term stress, poor sleep, illness, or burnout.
We’re all wired differently, and life experiences, including stress from years back, can shape how well our cortisol rhythm functions today. Restoring that rhythm can be transformative and is key to good health.
Remember, cortisol does not always increase in response to stress. Long-term stress can actually lead to lower cortisol levels. As practitioners, we also consider the total cortisol produced throughout the day (cortisol and cortisone), as well as how well you metabolise cortisol; how well your body activates, deactivates, and clears it.
Some people show high cortisol on paper but feel totally exhausted, because the hormone isn’t being processed properly. Others feel jittery or anxious without a clear cause. These patterns often appear in hormone testing and can be influenced by your genetics, inflammation, gut health, or even neurotransmitters such as dopamine and norepinephrine. It is a lot more nuanced than a simple ‘high’ or ‘low’.
Everyday Triggers that can dysregulate cortisol
- Skipping meals (especially breakfast)
- Over-exercising or HIIT when depleted
- Under-eating
- Low protein
- High sugar and high processed foods
- Too much caffeine or alcohol.
- Poor sleep or oversleeping.
- Long work hours with no breaks
- Scrolling at night (blue light = melatonin suppression)
- Negative self-talk and emotional stress
- Poor gut health, poor digestion or inflammation
- Other hormones out of balance – including thyroid, insulin, oestrogen, testosterone, progesterone
How to Reset Cortisol and Regain Control
Your body wants to be in balance. Here’s how to gently nudge cortisol back into its natural rhythm:
· Prioritise Sleep - Quality sleep is the most powerful way to lower cortisol. Aim for 7 to 9 hours. Turn off screens an hour before bed, swap harsh lighting for softer tones, and avoid caffeine after lunch. Try a hot magnesium bath.
· Ground Yourself Every Morning - Natural morning light helps reset your circadian rhythm and supports CAR. Step outside for at least 10 minutes of natural light. Use a Lumie light when mornings become darker. Going barefoot on grass or soil can help calm your nervous system and boost resilience for the day ahead (Known as grounding). You can also purchase grounding mats as well as grounding sheets for your bed.
· Nourish with Real Food - Start your day with protein-rich breakfasts. This stabilises blood sugar and prevents the rollercoaster of cravings and crashes that push cortisol up. Think eggs, Greek yoghurt, seeds, nut butters, or leftover chicken with avocado; anything nourishing and protein-rich. Avoid sugar, refined carbohydrates, and ultra-processed snacks that spike insulin and cortisol levels.
· Move Gently - Walking, yoga, stretching, and gentle strength training are ideal when cortisol levels are high or you’re burned out. Too much cardio can backfire. You only have so many energy stores, and if you use them all up trying to do cardio, you will be more exhausted, hungry, and inflamed. If you’re burnt out, less really is more. Start gently. Stretches, yoga, and strength training build muscle, which in turn activates the ‘hope molecule’ as we discussed in our protein series.
· Support Nutritionally - Cortisol depends on essential nutrients like vitamin C, B vitamins, magnesium, omega-3 fatty acids, and vitamin D. If your diet isn’t covering the bases, a targeted supplement plan can help. Seek advice from a practitioner, who will guide you on the best quality and type for your body. Remember, supplements vary significantly, with many high-street brands offering poor quality and suboptimal absorption.
· Build in Breathwork or Meditation - Even 5 minutes of daily deep breathing can help lower cortisol levels. Apps like Calm or Insight Timer are great, but simply focusing on exhaling longer than you inhale can also be beneficial.
· Reduce Blue Light in the Evenings - Switch off overhead lights, use night-mode filters, or wear blue-light blocking glasses. This helps your body transition to rest mode.
What About Testing?
If you suspect a cortisol imbalance, I strongly recommend testing with the DUTCH Plus test, which can map your full cortisol rhythm alongside other key hormones, such as oestrogen, progesterone, and DHEA, throughout the day. It’s a comprehensive way to assess the full picture.
Final Thoughts: You Can’t Fix Stress with More Stress
So many people try to “fix” weight gain or fatigue with more control, stricter dieting, harder workouts, and longer days. But if cortisol is driving the bus, the solution is not more pressure. It’s to support, soften, and nourish your way back to balance.
Weight, energy, cravings, and sleep all improve when cortisol levels follow a normal pattern.
In the final part of this series (Part 4), we’ll bring it all together, looking at how insulin, cortisol, ghrelin, leptin, thyroid and sex hormones work as a team (or fight like siblings), and how to get your hormonal house in order.
By Sarah Flower, Nutritionist.
