The Role of Insulin Resistance in Weight Gain

This article is not intended to provide medical advice. If you have, or suspect you have, any medical conditions, always seek assistance from a qualified medical professional.

When it comes to weight gain, there’s a simple truth that always holds: calories in versus calories out. This means that if you consume more calories than your body needs for energy, the excess will be stored as fat. This basic principle is rooted in the law of thermodynamics and applies to everyone, regardless of metabolic health. However, things can get a bit more complicated when insulin resistance comes into play, affecting how your body stores and uses energy. So, while the number of calories you eat matters, insulin resistance can change how your body handles those calories.

In this blog I want to break down what insulin resistance is and how it can affect weight gain and fat storage, especially for women with polycystic ovary syndrome (PCOS), women who are postmenopausal, and individuals with type 2 diabetes.

What is Insulin Resistance?

Insulin is a hormone produced by the pancreas, and its primary role is to help your cells absorb glucose (sugar) from the blood to use for energy. When everything is working smoothly, insulin keeps your blood sugar levels in check. But when your body becomes resistant to insulin, your cells don’t respond to the hormone as well, and more insulin is needed to do the same job.

Over time, insulin resistance causes a rise in insulin levels (hyperinsulinaemia) because your body is trying to compensate for the reduced effectiveness of the hormone. This might not seem like a big deal at first, but insulin doesn’t just manage your blood sugar—it also plays a significant role in fat storage. Elevated insulin levels can shift the way your body stores fat, especially in specific areas.

How Insulin Resistance Influences Weight Gain

When your insulin levels are consistently higher due to insulin resistance, your body becomes more efficient at storing fat. Insulin is sometimes called the “fat-storage hormone” because one of its key roles is to promote fat storage, especially in the abdomen. High insulin levels make it harder for the body to use fat for energy and easier to store it, especially in the form of visceral fat—the type of fat stored around your internal organs, which is more harmful to health.

Essentially, insulin resistance sets the stage for weight gain in a few ways:

Increased fat storage: With high insulin levels, your body is more inclined to store fat, particularly around the midsection.
Reduced fat burning: High insulin levels make it harder for your body to tap into fat stores for energy.
Cravings and appetite: Insulin resistance can affect your hunger signals, making you feel hungrier and crave more high-carb foods, leading to overeating.

Now, let’s look at how insulin resistance impacts different groups of people.

Insulin Resistance and PCOS

Polycystic ovary syndrome (PCOS) is a hormonal disorder that affects many women and is often associated with insulin resistance. Many women with PCOS struggle with weight gain, particularly around the abdomen. Even when eating a balanced diet, they may find it harder to lose weight due to insulin resistance. This is because the high insulin levels make it easier for the body to store fat and more difficult to burn it, even when following traditional weight-loss methods like calorie control.

The hormonal imbalances in PCOS also contribute to issues like increased appetite and cravings for sugary foods, which can make managing weight even more challenging.

Insulin Resistance Post-Menopause

As women go through menopause, hormonal changes can lead to insulin resistance, even if they’ve never had it before. Oestrogen levels drop during menopause, and this can make the body less sensitive to insulin, leading to higher insulin levels.

This is why many women find that they start gaining weight after menopause, especially around the belly. The body starts to store more visceral fat, which can be frustrating because it often feels like the usual diet and exercise strategies aren’t working as well as they used to.

Insulin Resistance and Type 2 Diabetes

Type 2 diabetes is essentially the full development of insulin resistance. When insulin resistance becomes severe, blood sugar levels stay elevated because the body can no longer produce enough insulin to manage it effectively. Weight gain is common in people with type 2 diabetes because of the same mechanisms we’ve discussed: elevated insulin levels leading to fat storage, particularly around the abdomen.

People with type 2 diabetes often find themselves in a cycle of weight gain and increased insulin resistance, making it challenging to manage both their blood sugar and their weight.

Other Groups Affected by Insulin Resistance

In addition to people with PCOS, post-menopause, and type 2 diabetes, several other groups are also affected by insulin resistance. Individuals with metabolic syndrome—a cluster of conditions including high blood pressure, abnormal cholesterol, and excess belly fat—often face insulin resistance, making it harder to lose weight and increasing their risk of heart disease and diabetes. Similarly, those with non-alcoholic fatty liver disease (NAFLD) commonly experience insulin resistance, leading to fat storage in the liver, which can result in further health complications.

Certain medical conditions and treatments can also influence insulin resistance. People with sleep apnoea, for instance, often experience disrupted sleep patterns that lead to insulin resistance and weight gain, particularly around the abdomen. Likewise, some medications, such as corticosteroids and antipsychotics, may cause elevated insulin levels, promoting fat storage. Cushing’s syndrome, a condition characterised by excess cortisol, can also lead to significant insulin resistance and weight gain.

Pregnancy can cause temporary insulin resistance, particularly in women with gestational diabetes, which increases the risk of developing type 2 diabetes later in life. Additionally, obesity itself is a significant contributor to insulin resistance, as excess fat tissue can disrupt normal insulin function. Older adults are similarly prone to insulin resistance due to changes in muscle (a drop in muscle) as they age, making weight management more difficult and increasing the risk of metabolic disorders.

Managing Insulin Resistance

Managing insulin resistance can indeed be challenging, but with the right approach, it is possible to achieve and maintain a healthy weight. While the basic principle of calories in versus calories out still applies, those with insulin resistance may need to approach weight management slightly differently, especially when it comes to the level of calorie deficit and exercise routine.

A key part of managing insulin resistance is focusing on a balanced diet rich in whole foods, such as vegetables, lean proteins, and healthy fats, while reducing the intake of refined carbohydrates and sugars. These foods help keep blood sugar levels stable, which in turn can lower insulin levels. A diet that minimises processed foods and emphasises complex carbohydrates, like whole grains and legumes, can support better insulin function.

Exercise plays an essential role in managing insulin resistance, particularly resistance training (weight lifting). Weight training helps build muscle mass, and since muscle is more insulin-sensitive than fat tissue, this can improve how your body responds to insulin. Increased muscle mass means your body can process glucose more efficiently, which is especially beneficial for people struggling with insulin resistance. Cardiovascular exercise, like walking, running, or swimming, is also important, as it helps burn calories and can improve insulin sensitivity over time.

For those with insulin resistance, achieving weight loss may require a greater calorie deficit than someone without this condition. This is because insulin resistance can make it harder for the body to tap into fat stores for energy. Elevated insulin levels promote fat storage, particularly around the abdomen, which can mean the body is more resistant to burning fat even when in a calorie deficit. As a result, someone with insulin resistance may need to be in a slightly higher deficit than someone without insulin resistance to achieve the same weight loss results. However, it’s important to maintain a balanced and sustainable approach, avoiding excessively low calorie intake, which can slow down metabolism and make the problem worse.

In some cases, medication such as metformin may be prescribed to help improve insulin sensitivity. This is often the case for individuals with conditions like type 2 diabetes or PCOS. Metformin helps lower blood sugar levels and improve how the body responds to insulin, making it easier to manage weight and maintain healthy blood sugar levels. Again, this is not medical advice, and only a medical professional, such as your doctor, can advise on this.

While insulin resistance may add an extra layer of difficulty to weight management, it can be managed through a combination of diet, exercise, and, where appropriate, medical support.

This article is not intended to provide medical advice. If you have, or suspect you have, any medical conditions, always seek assistance from a qualified medical professional.