Insulin Resistance Explained: A Nutritionist's Guide

In this guide, we will look at what insulin does, what insulin resistance actually means, signs that may warrant a conversation with your GP, its relationship with PCOS, and the lifestyle factors that are relevant to metabolic health.

What Is Insulin?

Insulin is a hormone produced by the pancreas. One of its key roles is helping the body regulate blood glucose, also known as blood sugar.

When you eat foods containing carbohydrates, they are broken down into glucose, which enters the bloodstream. As blood glucose rises, the pancreas releases insulin.

A useful way I explain insulin to clients is to ask them to picture insulin as a "key". Insulin helps unlock the body's cells so that glucose can move from the bloodstream into cells, where it can be used for energy or stored for later use.

This is not to be feared. In fact, it is a normal and essential process. Your brain, muscles and other tissues all rely on a steady supply of energy, and insulin is an important part of how your body manages that supply.

Insulin also has other functions beyond blood glucose regulation. It is involved in energy storage and metabolism, including the handling of carbohydrates, fats and proteins.

The amount of insulin released after eating varies depending on the meal, the amount and type of carbohydrate consumed, and individual factors. This means that having insulin released after eating is not itself a problem. It is a normal and healthy physiological response.

The issue arises when the body's cells become less responsive to insulin.

What Is Insulin Resistance?

Insulin resistance means that the body's cells respond less readily to insulin. In response, the pancreas may produce more insulin to help maintain normal blood glucose levels.

This can happen gradually and does not automatically mean that someone has diabetes. Think of it as needing a little more of the same "key" to open the lock. The insulin is still present, but the cells are not responding to it as efficiently as they previously did.

For some people, the body can compensate for reduced insulin sensitivity for a period of time. Blood glucose may remain within a healthy range because the pancreas is producing enough insulin to keep it there.

Over time, however, insulin resistance can be associated with changes in blood glucose regulation and an increased risk of metabolic conditions. This is one reason why the term frequently appears alongside discussions of prediabetes and type 2 diabetes.

Importantly, insulin resistance is not something that can reliably be diagnosed from how you feel or from a list of symptoms online. Assessment is a clinical matter and may involve your medical history and appropriate blood tests.

What Are The Signs Of Insulin Resistance?

There is no single symptom that tells you that you have insulin resistance. In fact, insulin resistance can occur without obvious symptoms, which is one reason self-diagnosis can be incredibly misleading.

Some features are commonly discussed in relation to impaired insulin sensitivity or changes in glucose regulation. These can include changes in weight, increased hunger or energy fluctuations. However, these experiences are common and can have many possible explanations.

For example, feeling tired after eating does not necessarily indicate insulin resistance. Neither does finding it difficult to lose weight. Sleep, stress, overall diet, activity levels, medications, hormones and numerous other factors can influence these experiences.

This distinction is important. Nutrition and wellness content can make insulin resistance sound like something you can identify simply by matching your symptoms to an online list. In reality, symptoms overlap with many other conditions and normal variations in health.

If you are concerned about your blood glucose, metabolic health, weight changes or symptoms that are affecting your wellbeing, arrange an appointment with your GP. They can assess your individual circumstances and determine whether further investigation is appropriate.

How Is Insulin Resistance Linked To PCOS?

Insulin resistance is commonly associated with polycystic ovary syndrome, or PCOS, although not everyone with PCOS will have insulin resistance. PCOS is a complex hormonal and metabolic condition. The relationship between PCOS and insulin is thought to involve several overlapping mechanisms.

When insulin levels are elevated, insulin can influence the ovaries and other tissues involved in hormone regulation. In some people with PCOS, this may contribute to increased androgen activity and changes in reproductive hormone signalling.

The relationship can also work alongside other factors associated with PCOS, including genetics, body composition and metabolic health. This is why PCOS cannot be reduced to simply being an insulin problem.

It is also important to remember that PCOS can occur in people across a wide range of body sizes. Insulin resistance is not determined simply by someone's weight or appearance.

For a more detailed explanation of the condition itself, see our guide to PCOS.

Can Diet Improve Insulin Resistance?

Diet is one part of the wider picture of metabolic health. A balanced dietary pattern can support healthy blood glucose regulation and insulin sensitivity, but there is no single food or diet that should be presented as a treatment for insulin resistance.

Rather than focusing on individual foods, it can be more useful to consider the overall pattern of eating.

Meals containing a combination of protein, fibre-rich carbohydrates, vegetables, healthy fats and other minimally processed foods can provide a range of nutrients while supporting a balanced diet.

Fibre is particularly relevant because it can influence digestion and the rate at which glucose enters the bloodstream. Sources include vegetables, fruit, pulses, wholegrains, nuts and seeds.

Protein and healthy fats can also form part of balanced meals. The aim is not to eliminate carbohydrates, but to consider the quality, quantity and context in which they are eaten.

Regular meals may also be helpful for some people, particularly when they support consistent energy intake and make it easier to maintain a balanced diet. Individual nutritional needs vary, however, so there is no universal meal pattern that is appropriate for everyone.

Movement is another important lifestyle factor. Physical activity helps muscles use glucose and is therefore relevant to insulin sensitivity. This does not mean you need to undertake intense exercise. Walking, resistance training, cycling and other forms of enjoyable movement can all contribute to an active lifestyle.

Sleep and stress also deserve attention. Poor sleep and chronic stress can influence hormones involved in appetite, energy regulation and glucose metabolism. Supporting good-quality sleep and finding sustainable ways to manage stress can therefore form part of a broader approach to metabolic health.

What About Chromium and Berberine?

Chromium is a mineral involved in normal macronutrient metabolism. Where relevant to an authorised health claim, chromium contributes to the maintenance of normal blood glucose levels. This is different from saying that chromium treats insulin resistance.

Berberine is a plant-derived compound that has attracted considerable research interest in relation to metabolic health. Some clinical studies have investigated its effects on markers such as blood glucose and insulin sensitivity, but the evidence and appropriate use require careful consideration.

How Can You Improve Insulin Sensitivity?

There is no single lifestyle change that guarantees improved insulin sensitivity. Instead, several everyday factors can contribute to overall metabolic health.

Eating a varied, balanced diet is a sensible starting point. Building meals around minimally processed foods, vegetables, fibre-rich carbohydrates, protein and healthy fats can support nutritional adequacy and more balanced eating patterns.

Regular movement is also important. Muscles are a major site of glucose use, and physical activity can influence how effectively the body responds to insulin. Finding activities that you enjoy and can maintain consistently is generally more useful than pursuing an unsustainable exercise routine.

Sleep is another often-overlooked factor. Consistently poor sleep can affect appetite regulation, stress hormones and glucose metabolism. Prioritising a regular sleep routine and sufficient sleep can therefore support broader metabolic wellbeing.

Stress management matters too. Stress is a normal part of life, but prolonged psychological stress can influence hormones and behaviours that are relevant to metabolic health. Simple strategies such as walking, relaxation practices, social connection and making time for enjoyable activities may be useful additions to a healthy lifestyle.

Body composition can also influence insulin sensitivity, but this should not be interpreted as a reason to pursue rapid or restrictive weight loss. Metabolic health is more complex than body weight alone.

If you have been diagnosed with a metabolic condition, have abnormal blood glucose results or have been advised to make specific dietary or lifestyle changes by your healthcare team, follow their individual guidance.

When Should You See Your GP?

This is particularly important if you have been told that your blood glucose is elevated, have a history of prediabetes or type 2 diabetes, have PCOS, or have other concerns about your metabolic health.

Your GP can consider your symptoms, medical history and risk factors and decide whether further assessment is appropriate. They can also explain what your blood test results mean in the context of your overall health.

It is worth remembering that insulin resistance is not something you can confirm using symptoms alone. Online calculators, symptom checklists and individual dietary responses cannot replace appropriate medical assessment.

If insulin resistance or another metabolic condition is identified, management should be guided by an appropriate healthcare professional.

From a nutrition perspective, healthy eating, regular movement, adequate sleep and sustainable stress management can all form part of a supportive lifestyle. The goal is not perfection, nor is it about fearing carbohydrates or individual foods. It is about understanding the bigger picture and making realistic choices that support long-term health.

The Bottom Line

Insulin resistance describes a reduced response to insulin, the hormone responsible for helping glucose move from the bloodstream into cells. It is closely associated with metabolic health and is commonly discussed in relation to PCOS, prediabetes and type 2 diabetes.

However, insulin resistance is not something you should try to diagnose yourself from symptoms alone.

Lifestyle factors including balanced nutrition, regular movement, good-quality sleep and stress management are relevant to insulin sensitivity and overall metabolic health. They should sit alongside, rather than replace, appropriate medical care.

Understanding insulin resistance does not need to mean becoming fearful of food or obsessing over blood glucose. A calm, evidence-informed approach is often the most useful place to start.

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