Are your hormones overriding the calorie equation

By Clare Goodwin

Last updated: September 3, 2020

Do you ever feel that despite eating really well and exercising, the weight that you want to lose is just not shifting?  No, it’s not that you can’t do the math properly, instead read on to learn more about hormones and weight gain.

My own personal experience and frustration of not being able to lose weight, even though I was eating well and exercising is the exact reason why I got into specialising in hormones and PCOS. From the age of 15- 23 I was a international athlete. I was a runner and then latterly a triathlete so I was completing at World Championships level for New Zealand. But while I was very good at what I did, I was always a heavier runner, and in these sports, weight is everything. Any ounce more that you are carrying is an a few seconds slower and in a 5km race where the winning time is 10ths of a second, that matters.

So I came under a lot of scrutiny from selectors and coaches who, even though I was very good and was not only NZ champion but also Australian as well, said that I was “out of condition.”

I remember vividly a selector at a national camp having a chat to me and saying, “Clare, you just need get in condition a bit more. It’s really not that difficult, it’s all about calories. You’re already training as much as we want, so we don’t want to change that, so you just need to eat a bit less.”

But the problem was that I wasn’t sneaking out for midnight macca’s runs. I was super diligent with my diet. I was completing my double degree with honours in nutrition and exercise science, so I wasn’t just aware of what I was eating, I was highly educated and meticulous with every calorie.

I knew that I was operating at a 500 calorie deficit, which should be enough to induce a pound a week body fat loss, but instead I was gaining weight, not rapidly, but about a pound or two a month.

I was baffled. We were learning at nutrition school that it really was about calories. I thought, I must be missing a trick.

So then I was graduated and still wasn’t able to sort out my own weight issue I was mortified. I thought that if I can’t work out this weight thing, then how can I help others?

But what I realise now I’m not an isolated case, I meet women every day, who are suffering from a similar frustraion , so if this is you, read on!

Hormones and weight gain: the story you aren’t told

I’m sure you’ve heard that losing, gaining, or maintaining weight is a simple matter of calories in vs. calories out. But what if I told you that this isn’t actually true. Although calories are important, hormones can override the calorie equation and prevent you from losing weight. If this wasn’t the case then certain medications wouldn’t lead to weight gain. The prime example of this is Cortisone. Cortisone is the synthetic form of cortisol, your long term stress hormone, and often used to treat asthma. One of the known side affects of Cortisone is weight gain. Now if calories were the only thing involved in weight, then that cortisone pill would have to be packed with a bucket of KFC to cause such weight gain.

Our most basic desire is survival. During our evolutionary days, the amount of stored energy (fat) that we had directly correlated with how long we could survive during a threatening situation, such as a famine. Fat storage was therefore an essential bodily function. Your body controls all of your essential bodily functions without you needing to think about them. Although you have a certain element of control over them – like altering your breathing or holding your breath – your body will always have the superior power. If you hold your breath for too long then you’ll pass out, but your survival mechanisms will kick in and you’ll start breathing again.

A similar principle applies to fat storage. While you can manipulate calories, your body has a primitive system that can override the intended results of such a deficit. For example, it can slow down your metabolism and increase hunger in times of famine. Unfortunately, your body hasn’t learned that the local corner shop has enough chocolate bars and crisps to sustain you through the apocalypse. The fat preservation mechanisms that ensured our survival hundreds and thousands of years ago are still in place. It’s here that the roles of your hormones – specifically the thyroid, insulin, and stress hormones – come in. Let’s take a closer look at each of them.

Thyroid Hormones

The thyroid is a butterfly-shaped gland that sits at the base of your neck. It’s the chief controller of metabolism. When the body thinks that it might be entering a state of famine, it sends a message to the thyroid saying, “Whoa, slow everything down! We don’t want to waste fuel reserves!”

If you don’t produce a sufficient amount of thyroid hormones (hypothyroidism) then your metabolism slows down. As a result, the body retains as much energy as possible. It does this by reducing body temperature and clinging onto fat reserves. This makes weightloss very, very difficult.

Hypothyroidism can be diagnosed by a blood test, via your doctor and you can find the tests you should be asking for in this article. Thyroid conditions are incredibly common in women, with one in eight women developing one during her life. However, hypothyroidism is so frequently missed because the weight gain symptom is often disregarded as being due to overeating.

A good way to tell whether your thyroid is performing as it should is to measure your temperature every morning. If you see that it’s often in the low 36’s then that’s a pretty good indication that something’s not right with your thyroid..

Other symptoms of thyroid dysfunction include:

  • Fatigue or feeling tired and sluggish.
  • Poor recovery from exercise.
  • Depression or low mood.
  • Weight gain, or finding it hard to lose weight, even with a low calorie diet.
  • Thinning hair and/or the outer third of your eyebrow thinning.


Cortisol is a hormone associated with long-term stress. You can think of it as a big brother to adrenaline, the short-term stress hormone.

During our evolutionary days, stress would only be experienced if there was a physical threat, such as famine or tribal warfare. Although we are now living in a drastically different environment, our bodies and brains haven’t evolved at the same rate that the world has. The body doesn’t know how to differentiate between physical threat and emotional or psychological threat. To your brain, it’s the same thing.

In a physical threat situation, you would have needed to fight or flee. Both of these would have required physical exertion. In response to this, your body would have released lots of glucose into the bloodstream to provide energy for running and fighting. However, in our modern world we’re more likely to be sat at a desk, sipping on our third flat white of the day.
We still experience stress and our bodies still have the same evolutionary response. But then we don’t really do anything that requires energy. The result? Your body has to do something with the excess glucose, so it stores it away as fat.

High cortisol levels aren’t just caused by running late or having a mountain of deadlines at work. They also come from:

  • Doing too much high intensity aerobic exercise (40 minutes or more increases cortisol for up to 48 hours after exercise).
  • Too little sleep.
  • Poor gut health, or any other infection your body is fighting.
  • Eating food that you’re intolerant to.
  • Dieting.
  • Eating too few carbs.

Like many of my patients, my attempts to lose weight actually caused me to gain weight. My day would start at 6am: I’d wake up groggy and reluctantly head out for a run or an hour of CrossFit. By the time I reached my desk, I’d still be feeling exhausted. Coffee would keep me going until the brain fog and exhaustion lifted at midday. My days were spent rushing between meetings and then, if I wasn’t working late, I’d be out in the evening attempting to have a social life. Most evenings, I wouldn’t get home until 11pm.

Unsurprisingly, I was so stressed that my cortisol levels were through the roof. Despite exercising and restricting carbs, I was still gaining weight. My natural reaction to this was to exercise more and eat less, but this just raised my cortisol levels further and fuelled a vicious cycle.

How Do You Know Whether High Cortisol’s Causing You Problems?

  • Do you feel tired for at least 30 minutes after an exercise session?
  • Do you often get injured or sick?
  • Do you always wake up tired, even after 7 (or more) hours of sleep?
  • Do you struggle to get going in the morning, then feel tired but wired at night?
  • Do you depend on coffee to get you going in the morning?

If you nodded your head at any of those then you might want to consider that it’s your stress hormones causing your weight gain. If it is then it might be time to cut back on the high intensity exercise, up the calories, and get more sleep.


Insulin is your storage hormone. It’s the one that tells your muscle and liver cells to take up glucose after you’ve eaten and store it away for later use. It’s excreted by the pancreas and binds to a receptor on the cell to open it up, similar to the way a key opens a door. When the key has been used too much, or there is chronic low grade inflammation, the lock starts to get a bit worn and clogged up. In other words, the key no longer fits. This is insulin resistance, which is the precursor to Type 2 Diabetes. When your body is unable to get sugar into your cells, it stores it as fat instead. This is the reason why insulin resistance leads to weight gain.

Insulin resistance isn’t just caused by eating too many doughnuts and not doing enough exercise. It can also be caused by too much high intensity exercise, poor gut health, too little sleep, the birth control pill, and even eating food that you are intolerant to.

I had just competed in World Championships Triathlon when I was found out that I was severely insulin resistant. I was over-training (20 hours a week) and chronically sleep deprived. Several courses of antibiotics for childhood tonsillitis meant that I already had poor gut health, and I was fuelling my training with sports drinks and gels. The result of all of this proved to be a devastating combination for my poor body, leading me to becoming more and more insulin resistant.

Symptoms of Insulin Resistance:

  • Feeling hungry only 2 hours after eating.
  • Feeling shaky and jittery if you haven’t eaten for 2 hours.
  • Sugar cravings.
  • Feeling that you must have sugar after meals.
  • Weight gain, especially around your stomach.
  • Urinating often and feeling thirstier than usual.

In approximately 10% of women, insulin has an additional effect. It acts on your ovaries and causes them to overproduce testosterone. This results in a condition which affects 10-20% of women in the UK, Polycystic Ovarian Syndrome (PCOS). Due to insulin, one of the symptoms of PCOS is weight gain. If you’re suffering from sugar cravings and weight gain then you might want to get your insulin and sex hormones tested.


Weight isn’t just a simple matter of calories in vs. calories out. While calories are important, hormones that can override the calorie deficit and stop you from losing weight. The three most common hormones that can cause weight gain are thyroid hormones, cortisol, and insulin.

If you’re reducing your calories and/or exercising to reach a 500 calorie deficit, but the weight isn’t shifting, then it’s time to address you hormones. Not only could this help with your weight loss efforts, it could also make you aware of any other problems that you have.