Insulin Resistance: The Hidden Driver of Fatigue, Cravings and Weight Gain
Insulin resistance is one of the most overlooked drivers of poor energy, weight gain, sugar cravings, brain fog and hormonal imbalance.
The frustrating part is that many people do not know they have it.
They may have been told their fasting glucose is normal. Their HbA1c may still be within range. They may not have diabetes. But they still feel tired, hungry, foggy, inflamed and stuck in a body that does not respond well to diet or exercise.
At Wave Functional Health, we often see this pattern in patients who say:
"I eat fairly well, but I still gain weight."
"I crash in the afternoon."
"I crave sugar after dinner."
"I wake up around 2 or 3am."
"I feel tired even after sleeping."
"My blood tests are normal, but something feels off."
From a functional medicine perspective, these symptoms can be early warning signs that the body is struggling to manage blood sugar, insulin, inflammation and energy production.
What is insulin?
Insulin is a hormone made by the pancreas. Its main role is to help move glucose from the bloodstream into the cells, where it can be used for energy or stored for later.
After you eat carbohydrates, your blood glucose rises. Your pancreas releases insulin. Insulin then signals your muscle, liver and fat cells to take up glucose.
That is normal.
The problem begins when your cells stop responding to insulin properly. This is called insulin resistance.
When this happens, the pancreas has to produce more insulin to achieve the same effect. In the early stages, your blood glucose may still appear normal because your body compensates by producing extra insulin.
This is why insulin resistance can be missed.
By the time glucose and HbA1c become clearly abnormal, the problem may have been building for years.
Insulin resistance is not the same as diabetes
Insulin resistance can exist long before type 2 diabetes develops.
Diabetes Australia explains that type 2 diabetes occurs when the body becomes resistant to insulin and gradually loses the ability to produce enough insulin from the pancreas. Lifestyle changes such as improving diet and increasing physical activity can significantly slow or even stop the progression of type 2 diabetes in many people. (Diabetes Australia)
The National Institute of Diabetes and Digestive and Kidney Diseases notes that people with insulin resistance and prediabetes often have no symptoms, which is one reason these conditions can go unnoticed. (NIDDK)
This matters because many people wait until they are diagnosed with prediabetes or diabetes before taking metabolic health seriously.
That is a mistake.
The earlier you detect insulin resistance, the easier it is to change the trajectory.
Common signs of insulin resistance
Insulin resistance does not always create obvious symptoms. But when symptoms do appear, they often show up as energy, appetite, mood and weight problems. These are the patterns we look for at Wave.
Why insulin resistance makes you tired
The irony of insulin resistance is that you can have plenty of glucose in the blood, but your cells may still struggle to use it efficiently. Your muscles, brain and mitochondria rely on stable energy delivery. When insulin signalling becomes impaired, the body may swing between high and low energy states.
A healthy person should be able to eat a balanced meal, use glucose efficiently, store some for later, burn fat between meals and maintain stable energy. Insulin resistance makes that harder.
This does not mean carbohydrates are bad. It means the body needs to be metabolically flexible enough to handle them well. Metabolic flexibility is what we are working to restore.
Why you feel tired
even after eating.
Why you crave sugar
Sugar cravings are not always a discipline problem.
They can be a physiology problem.
If your cells are not receiving or using energy well, your brain may interpret that as a need for fast fuel. This can show up as cravings for chocolate, biscuits, bread, cereal, sweets, juice, soft drink or late-night snacks.
Stress makes this worse.
Poor sleep makes it worse.
Low protein intake makes it worse.
Skipping breakfast can make it worse.
Under-eating during the day can make it worse.
Excess caffeine can make it worse.
The answer is not simply to “try harder.” The answer is to stabilise the system so your appetite signals are less chaotic.
The insulin and cortisol connection
Blood sugar and stress physiology are closely linked.
Cortisol is one of your main stress hormones. It helps mobilise energy when your body perceives a threat. This is useful in short bursts.
But chronic stress, poor sleep, overtraining, emotional strain, shift work, trauma, pain and inflammation can keep cortisol patterns disrupted.
When cortisol is elevated or mistimed, blood glucose can rise. The body may then need more insulin to manage that glucose. Over time, this can contribute to insulin resistance.
This is one reason some people say:
“I am eating well, but I still cannot lose weight.”
If the nervous system is under chronic stress, the metabolism may be receiving a constant signal that it is unsafe to burn, repair and regulate properly.
Insulin resistance and brain fog
Insulin is not only a blood sugar hormone. It also plays roles in the brain. If you experience brain fog after meals, afternoon crashes, poor concentration, irritability when hungry, or difficulty thinking clearly after high carbohydrate foods, blood sugar regulation deserves attention.
A 2022 review reported that brain insulin resistance has been associated with age-related declines in memory and executive function — suggesting that metabolic health and brain health are more closely connected than is commonly recognised.
PMC: Brain insulin resistance and cognitive function (Malin et al., 2022) →A 2024 review described brain insulin resistance as a plausible therapeutic target in the prevention of cognitive decline and Alzheimer's disease — adding to growing evidence that how well the brain uses insulin has long-term neurological consequences.
PubMed: Brain insulin resistance and Alzheimer's disease (Rhea et al., 2024) →This does not mean insulin resistance automatically causes dementia. But it does mean that metabolic health and brain health are connected — and that blood sugar regulation is worth taking seriously well before any disease threshold is reached.
Insulin resistance and hormones
Insulin resistance can affect hormonal health in both men and women.
In women, insulin resistance is strongly associated with polycystic ovarian syndrome, irregular cycles, acne, weight gain, increased androgens and fertility challenges.
In perimenopause and menopause, declining oestrogen can make blood sugar regulation more difficult for some women. This is one reason weight gain, sleep disruption, cravings and mood changes may become more noticeable during the hormonal transition.
In men, insulin resistance is often associated with abdominal weight gain, low energy, poor recovery, inflammation and reduced testosterone signalling.
This does not mean insulin is the only hormone that matters.
It means insulin often sits upstream of many hormonal complaints.
If insulin remains high, it becomes much harder to optimise thyroid function, sex hormones, adrenal rhythm, sleep, body composition and inflammation.
Why normal blood sugar may not be enough
Many people only have fasting glucose and HbA1c checked. These markers are useful, but they do not always detect early insulin resistance. A person can have normal glucose but high insulin — meaning the body is compensating. The goal is not to diagnose everyone with a disease. The goal is to identify metabolic strain early enough to intervene intelligently.
← Scroll to see full table
| Marker | What it shows |
|---|---|
| Fasting glucose | How much glucose is in the blood at one point in time. Useful but does not directly reveal how much insulin the body had to produce to keep glucose controlled. |
| Fasting insulin | How much insulin the pancreas is producing at rest. A normal glucose with elevated fasting insulin is one of the clearest early signs of insulin resistance — and it is rarely tested on a standard panel. |
| HbA1c | An estimate of average blood glucose over roughly the previous 2 to 3 months. Useful for tracking trend but does not detect compensated insulin resistance in the early stages. |
| Triglycerides | Elevated triglycerides are one of the earliest and most consistent markers of insulin resistance and poor metabolic flexibility — often rising years before glucose becomes abnormal. |
| HDL cholesterol | Low HDL alongside high triglycerides is a classic metabolic pattern associated with insulin resistance and increased cardiovascular risk. |
| High-sensitivity CRP | A marker of systemic inflammation — closely linked to insulin resistance and metabolic dysfunction. Elevated hsCRP suggests the inflammatory component of the metabolic picture needs to be addressed. |
| Liver enzymes and uric acid | Early signs of fatty liver and metabolic strain that can accompany insulin resistance before other markers shift significantly. |
| Body composition and waist circumference | Visceral fat is metabolically active and directly worsens insulin resistance. Waist circumference and InBody 580 body composition scanning provide information no blood test can reveal. |
The functional medicine approach
A functional medicine approach does not simply ask whether someone is diabetic. It asks a broader set of questions that reveal metabolic health well before disease thresholds are reached.
The questions we ask at WaveWhat you can start doing
You do not need a perfect plan to start improving insulin sensitivity. Start with the basics and do them consistently. Insulin resistance is rarely caused by one thing — it is usually the result of multiple pressures building over time. Addressing it follows the same logic.
Stress physiology is not soft medicine. It is metabolic medicine. Breathing, sunlight, walking, time outdoors, connection, and better boundaries all reduce the load on the system — and that load directly influences how well insulin works.
If you are tired, gaining weight, craving sugar, waking at night, or struggling with brain fog after meals, insulin resistance should be considered. Do not wait until your glucose is clearly abnormal.
Eat protein at breakfast
A high carbohydrate breakfast can set up a blood sugar rollercoaster for the rest of the day. Build breakfast around protein, fibre and healthy fats — eggs with vegetables, Greek yoghurt with nuts and berries, or leftover dinner with extra vegetables.
Walk after meals
A 10 to 20 minute walk after meals helps muscles take up glucose and reduces post-meal blood sugar spikes. This is one of the simplest and most effective interventions for metabolic health available.
Strength train consistently
Muscle is one of the main places glucose is stored. More muscle generally means better glucose disposal and improved metabolic flexibility. Two to four structured strength sessions per week can make a meaningful difference.
Reduce ultra-processed foods
Ultra-processed foods are usually low in fibre, low in micronutrients and high in refined carbohydrates and poor-quality fats. They make appetite regulation harder and directly worsen insulin sensitivity over time.
Prioritise sleep
Poor sleep reduces insulin sensitivity, increases hunger hormones, increases cravings and worsens stress physiology. If your sleep is poor, your blood sugar control will usually suffer alongside it.
Manage stress physiology
Breathing, sunlight, walking, time outdoors, connection, counselling, nervous system work and better boundaries all help reduce the stress load on the system. This is not soft medicine. It is metabolic medicine.
When to seek help
If you are tired, gaining weight, craving sugar, waking at night, or struggling with brain fog after meals, insulin resistance should be considered.
This is especially important if you have a family history of type 2 diabetes, high blood pressure, high triglycerides, fatty liver, PCOS, gestational diabetes, abdominal weight gain, sleep apnoea, or a sedentary lifestyle.
Healthdirect describes metabolic syndrome as a group of risk factors that increase the chance of serious long-term conditions such as stroke, heart disease and type 2 diabetes. (Healthdirect)
Do not wait until your glucose is clearly abnormal.
At Wave Functional Health on the Gold Coast, we look at metabolic health through a wider lens: blood sugar, insulin, body composition, inflammation, hormones, gut health, nervous system regulation, sleep and lifestyle.
Because when insulin resistance is addressed early, people often notice improvements in energy, cravings, weight, mood, focus and long-term disease risk.
Your metabolism is not broken.
But it may be asking for a better signal.
Your metabolism is not broken.
But it may be asking for a better signal.
At Wave Functional Health we look at metabolic health through a wider lens — blood sugar, insulin, body composition, inflammation, hormones, gut health, nervous system regulation, sleep and lifestyle. Because when insulin resistance is addressed early, the trajectory can change.
Book a ConsultationDr Matt le Roux is a chiropractor and functional medicine practitioner at Wave Functional Health, Suite 326, 34-36 Glenferrie Drive, Robina QLD 4226. He works with patients across the Gold Coast to identify and address the root causes of chronic health presentations.