Hormones and weight gain

Hormones and weight gain.

What’s the link between women’s hormones and weight gain? 

If you’ve ever wondered why men lose weight more easily than women, there’s a good reason. For many years, due to lack of female representation in clinical trials, a woman’s body was treated as if it were just a smaller version of a man’s! But more and more research is pointing to the fact that our female bodies are functionally and hormonally different, and that means the causes of weight gain are very different too.

In this article we discuss the key hormones involved in weight gain for women – from insulin and cortisol to estrogen and testosterone – and how comprehensive hormone testing can help to identify the root cause.

Why do hormones cause weight gain?

Generally, hormones cause weight gain because of their effect on metabolic processes. 

The two hormones that are most implicated in weight gain are cortisol and insulin. Both these hormones can cause us to gain weight and can prevent us from losing weight too. Plus, if these hormones are out of balance, they can have a knock on effect which can cause our other hormones – such as thyroid hormone, estrogen and progesterone – to also be out of balance. These hormones in turn can also cause weight gain!


Let’s start with insulin and how it can lead to weight gain.

WHat is insulin?

Insulin is a hormone, made in the pancreas, that tells our cells to take up glucose for energy. 

When there’s glucose in the bloodstream, for example after a meal, our body responds by increasing insulin levels. Insulin signals to the body to store glucose, first in the liver as glycogen and then as fat in our fat cells. 

In between meals, insulin levels fall, signalling to the body that it should burn stored energy. But if we have insulin resistance, insulin levels tend to stay consistently high. 


Insulin resistance means that the cell’s metabolic processes, that are supposed to turn food into energy, are not functioning properly. This can result in less energy, more inflammation and an increased tendency to gain fat, especially around the waist. 

Insulin resistance can also cause high cholesterol, high triglycerides and fatty liver (fat accumulation in the liver). High insulin also blocks fat burning as well as promotes fat storage because the body does not get the message that it should be using our fat storage for energy. 

High insulin can also lead to weight gain in other ways. 

Firstly, it increases leptin resistance, which can lead to more weight gain because leptin is our satiety hormone. Secondly, it increases inflammation, which can increase cortisol, lead to insulin resistance and can cause sex hormone imbalances. Thirdly, it increases testosterone, which leads to abdominal weight gain. 

Interestingly, if we have insulin resistance, while some cells become resistant to insulin (like our muscle cells), some cells are stimulated by the too-high levels of insulin. This is what happens in the ovaries.

Learn more about insulin resistance and hormones.

testosterone AND WEIGHT GAIN

One of the knock-on effects of high insulin is high testosterone. This is why insulin resistance is the most common of the four types of PCOS, responsible for around 70% of cases. 


High insulin can increase testosterone in various ways. 

Firstly, insulin can directly cause the theca cells in the follicle of the ovaries to increase the production of testosterone. Secondly, too much insulin stimulates the pituitary to make more Luteinising Hormone (LH), which stimulates more androgens. Thirdly, too much insulin also lowers SHBG (sex hormone binding globulin), which leads to more free/unbound testosterone.

Testosterone, in turn, decreases insulin sensitivity. What can happen then is that relatively high androgens including testosterone increase the risk for insulin resistance and insulin resistance can increase androgens, resulting in a vicious cycle. 

This is the main reason for weight gain and obesity in women with PCOS.

Lowering insulin is therefore key to weight loss. The best way to reverse insulin resistance is to balance your blood sugar but other strategies can help too, including personalised supplementation.

Read more about insulin resistance and PCOS. 


The other hormone that is important to address for weight loss is cortisol, one of our stress hormones. 

It’s not just external stress (real or imagined) that affects our stress response. Internal stressors such as inflammation, blood sugar dysregulation and circadian disruption all trigger the HPA axis (which controls our stress response) and have an effect on our cortisol levels. 

Cortisol causes our blood sugar levels to rise and therefore stress is a risk factor for insulin resistance. Stress and dysregulated cortisol can also lead to a slower thyroid and therefore slower metabolism. 

Read more about stress and the HPA axis.

FUTURE WOMAN home hormone test kit


Our female sex hormones plays an essential role in energy metabolism and body composition. 

High estrogen

High estrogen (one of our key sex hormones) can lead to weight gain (as well as increase fluid retention and inflammation) when we have too much of it AND when we have too little of it because it is an important metabolic hormone and increases insulin sensitivity. 

Read more about high estrogen.

Another important hormone to consider is thyroid hormone. 

Thyroid hormones

Thyroid hormone regulates metabolic processes essential for normal growth and development, as well as regulating metabolism. It is well established that thyroid hormone status correlates with body weight and energy expenditure. Hypothyroidism, reduced thyroid hormone levels, is associated with reduced resting energy expenditure, weight gain, increased cholesterol levels and reduced ability to lose fat.

Thyroid hormone is also directly involved in the control of insulin secretion and glucose homeostasis, and hypothyroidism is associated with decreased insulin sensitivity and dysglycemia. In fact, T3 hormone (our ‘active’ thyroid hormone) is often low in people with blood sugar problems. Hypothyroidism is therefore a risk factor for, and can also worsen, insulin resistance.

Read more about the signs and symptoms of thyroid imbalance.

Weight gain in menopause

One of the most common symptoms of perimenopause and menopause is increased weight gain despite no change in exercise or diet routines. The most common type of weight gain in perimenopause is abdominal weight gain (apple shaped). 

There are a few causes of weight gain during this time.

Menopause is a risk factor for insulin resistance, in part because of our changing levels of estrogen and progesterone. When we have higher insulin levels, we likely have reduced metabolic flexibility, which is when our cells can’t efficiently switch from using glucose for energy to using fat. 

Read more about insulin resistance and menopause.

When women lose estrogen during menopause, they also lose estrogen’s protective effects. Loss of estrogen is directly linked to increased visceral fat, higher cholesterol levels and insulin resistance. 

The natural testosterone dominance of menopause can also worsen insulin resistance.

The HPA axis becomes destabilised in perimenopause and therefore there is a greater risk of thyroid imbalance. Our thyroid hormones work intricately with our sex hormones an imbalanced estrogen can suppress the thyroid. Therefore, the thyroid is more likely to be underactive (causing symptoms such as low energy, weight gain, constipation and cold hands and feet). 

Read more about the signs and symptoms of perimenopause.

Perimenopause and weight gain

The benefits of testing for weight gain

Comprehensive hormone testing can be really helpful to see which hormones might be out of balance and contributing to weight gain. 

Our FUTURE WOMAN Advanced Hormone Test gives insight into your estrogen levels as well as how well estrogen is being detoxified through the liver (estrogen metabolites). We can also see your androgen levels, including testosterone, and the preferred pathway for testosterone metabolism. We can also see your adrenal function, daily cortisol pattern and total cortisol production. Finally, we can gain insight into your thyroid function as well. With all this information we can get to the root cause of your weight gain and why you might be finding if hard to lose weight. Included with all our hormone tests is a personalised healthplan, with tailored recommendations for supplements, diet and lifestyle changes to reverse your symptoms.


“FUTURE WOMAN have changed my life. For years I’ve struggled with getting the right testing to understand what was wrong with my body. GPs have only ever focused on my BMI being too high as the cause of my problems, and losing weight being the only solution. Once I found FUTURE WOMAN I did the Advanced Hormone Test and worked with Francesca who has been nothing but supportive and incredibly helpful. The results showed why I’ve been struggling to lose weight, along with explaining a magnitude of other symptoms I’d be suffering with, and I now have a full comprehensive (and mostly natural) plan on how to heal this. It’s been such a weight off my shoulders to fully understand what is wrong, where the issues come from and to begin to see my body heal.”


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