Breaking Down Insulin Resistance
In this article, we’re diving deep into what insulin resistance actually is, why it matters (even if your blood sugar is normal), what issues it can cause, how to know if you have insulin resistance, and how we can properly assess and address it early.
Insulin’s role in the body
Insulin is a hormone produced by the pancreas that helps regulate blood sugar by allowing glucose to move from the bloodstream into cells for energy. It also signals the body to store excess fuel as glycogen or fat after we eat.
Key roles of insulin
Glucose regulation: Helps move glucose from the bloodstream into cells (especially muscle and fat) to be used for energy or stored.
Energy storage: Promotes glycogen storage in the liver and muscle.
Fat metabolism: Stimulates fat storage (lipogenesis) and inhibits fat breakdown (lipolysis).
Protein metabolism: Supports amino acid uptake into cells and promotes protein synthesis.
What is insulin resistance?
In insulin resistance, cells do not respond as effectively to insulin’s signal, so the body compensates by producing more insulin to maintain normal blood sugar levels (more on why this is a problem later)
All tissues with insulin receptors can become insulin resistant, but the primary tissues involved in insulin resistance are the liver, skeletal muscle, and adipose (fat) tissue. These tissues play VERY important roles in regulating blood sugar, energy storage, and metabolism.
In the early stages, blood sugar levels often remain normal because the pancreas is able to compensate by producing more insulin. However, insulin levels are elevated behind the scenes. Over time, this compensation may become less effective, leading to elevated blood sugar, prediabetes, and eventually type 2 diabetes.
Common causes of insulin resistance:
Nutritional imbalances, especially excess refined carbohydrates and eating in a caloric surplus.
Physical inactivity
Visceral/Abdominal obesity
Genetics
Aging
Medications
Common signs & symptoms of insulin resistance
Fatigue, particularly after meals
Difficulty losing weight
Increased fat storage, especially around the abdomen
Increased hunger or cravings (particularly for carbohydrates)
Energy crashes during the day
Brain fog
Irregular menstrual cycles
Acne
Acanthosis nigricans
Why chronically high insulin is a problem
While insulin is essential for regulating blood sugar, consistently elevated insulin levels can disrupt normal metabolic function and contribute to a wide range of health issues.
1. Increased fat storage and difficulty losing weight
Insulin signals the body to store energy. When insulin levels are high, the body is more likely to store glucose as fat, particularly in the abdominal area.
At the same time, high insulin suppresses fat breakdown. This makes it more difficult for the body to access stored fat for energy— in other words, it’s harder to burn fat.
This is why insulin resistance is often associated with increased abdominal fat. You might be asking… why abdominal fat specificially? The abdominal area contains visceral fat, which is more metabolically active and particularly responsive to insulin’s fat-storing effects.
2. Disrupted energy levels and increased fatigue
Insulin resistance reduces the ability of glucose to enter cells — so even when blood sugar is normal or high, cells can’t access fuel efficiently. As a result, less glucose is available for glycolysis and mitochondrial ATP production, which can contribute to low cellular energy.
At the same time, chronically elevated insulin can drive rapid fluctuations in blood sugar, leading to energy crashes, fatigue, and brain fog. Over time, this impaired fuel delivery and unstable glucose regulation make the body less efficient at producing steady, sustainable energy throughout the day.
3. Increased risk of type 2 diabetes
In the early stages of insulin resistance, the pancreas compensates by producing higher amounts of insulin to keep blood sugar levels normal. For a time, this increased output maintains stability without flagging anything on routine bloodwork.
Over the years, however, the pancreas may no longer be able to meet this demand. As insulin production becomes insufficient, blood glucose begins to rise, progressing to pre-diabetes and eventually type 2 diabetes. Insulin resistance often precedes a diagnosis of type 2 diabetes by 10–15 years— which is why I routinely assess fasting insulin in my patients. It’s something we can identify early and address before blood sugar becomes abnormal.
4. Increased cardiovascular risk
Insulin resistance ramps up cardiovascular risk through multiple interconnected pathways, even before diabetes develops.
Increased triglycerides: normally, insulin signals adipose tissue to stop breaking down fat— in IR, this signal is blunted, which means fat cells release more free fatty acids (FFAs) into the bloodstream than they should. Those excess FFAs go to the liver, where they are turned into triglycerides. This is how insulin resistance causes fatty liver (NAFLD).
Reduced HDL cholesterol: HDL is our “good cholesterol” that picks up cholesterol from your arteries and takes it to your liver to excrete. When there are too many triglycerides from the liver, HDL gets loaded with triglycerides— which then get destroyed by liver enzymes. Result is less HDL in circulation.
Endothelial dysfunction: insulin resistance harms the endothelium (the inner lining of our blood vessels) by interfering with insulin’s role in the blood vessels. Normally, insulin balances out vessel relaxation (triggers nitric oxide) & constriction (boosts endothelin-1). In IR, the nitric oxide pathway gets blocked, while endothelin-1 continues to constrict blood vessels. The outcome of this is stiffer blood vessels.
Increased inflammation: IR triggers immune cells (like macrophages) to release pro-inflammatory signals (like TNF-α, IL-6). Inflammation increases cardiovascular risk because it directly contributes to the development & instability of atherosclerotic plaques.
5. Hormonal disruption
Insulin influences other hormones, including estrogen, androgens, progesterone, cortisol & leptin:
Estrogen: insulin promotes fat storage, and fat tissue is hormonally active & produces estrogen. This increased estrogen can lead to a relative estrogen dominance, especially if paired with low progesterone from anovulation. Common symptoms of estrogen dominance are heavy/irregular periods, worsened PMS (bloating, cramps & mood swings) & breast tenderness.
Androgens: High insulin stimulates the production of more androgens, which can contribute to symptoms such as acne, hair thinning, hirsutism & irregular menstrual cycles. This mechanism is a key driver of PCOS.
Progesterone: Elevated insulin & androgens can also interfere with normal ovulation. When ovulation is irregular, progesterone production decreases. This impacts cycle regularity, mood stability, sleep quality & ability to conceive.
Cortisol: Insulin resistance is associated with increased cortisol levels and impaired stress response. Elevated cortisol can further worsen insulin resistance by increasing blood sugar and promoting fat storage, particularly in the abdominal area. This contributes to fatigue, weight gain & metabolic dysfunction.
Leptin: Insulin normally works with leptin (fullness hormone from fat cells) to signal the brain to stop eating, while suppressing ghrelin (hunger hormone from the stomach). With chronically high insulin, we can start to see leptin resistance— meaning the brain ignores leptin’s “I’m full” message- despite high levels. What this looks like clinically is feeling hungry after eating, cravings for carbs/sugar and having a hard time feeling satisfied with food intake.
How insulin resistance is assessed
Common markers used to evaluate insulin resistance include:
Fasting insulin: often missed in routine bloodwork, this test measures baseline insulin levels after 8-12 hours without food— revealing how hard your pancreas works to maintain blood sugar. This test flags insulin resistance early (before glucose changes)
Fasting glucose: included in routine bloodwork, this test measures blood sugar after 8-12 hours without food— showing your baseline glucose control. This can be normal even with insulin resistance.
Hemoglobin A1c: included in routine bloodwork, this test reflects average blood sugar over approximately three months. May remain normal for years despite rising insulin.
HOMA-IR (Homeostatic Model Assessment of Insulin Resistance): a calculated value using fasting glucose and fasting insulin that provides a more comprehensive estimate of insulin sensitivity. HOMA-R values >2 indicate insulin resistance. The HOMA-IR is best for screening for insulin resistance.
Oral glucose/insulin tolerance test: similar to the OGTT ran in pregnancy, this test challenges your body with a 75g glucose drink (after fasting), then measures blood glucose (and often insulin) at intervals (0, 30, 60, 90, 120+ min) to see how well you handle a sugar load. This test is best for confirming the diagnosis of insulin resistance.
Diagnosed with insulin resistance?
The good news is that insulin resistance is reversible.
Insulin resistance is highly responsive to lifestyle and metabolic intervention — especially when identified early.
Because insulin resistance develops gradually, it can also improve gradually when the underlying drivers are addressed (it takes at least 3 months to see changes). The body’s cells can become more responsive to insulin again, insulin levels can decrease, and metabolic function can normalize.
How I approach insulin resistance
My goal is not simply to “lower blood sugar.” It’s to improve insulin sensitivity at the cellular level and support long-term metabolic health.
Treatment is individualized, but it typically focuses on several core pillars:
1. Building and preserving muscle
Skeletal muscle is one of the primary tissues responsible for glucose uptake (think of your muscles as a sponge for glucose). Increasing muscle mass improves insulin sensitivity and allows the body to regulate blood sugar more efficiently. Resistance training is one of the most effective interventions for reversing insulin resistance.
2. Supporting stable blood sugar
Rather than focusing on restriction alone, I focus on supporting stable blood sugar throughout the day. This often includes:
Prioritizing protein and fibre
Reducing highly refined carbohydrates
Consuming balanced meals
Avoiding large glucose spikes
The goal is to reduce excessive insulin stimulation and allow insulin levels to normalize over time.
3. Addressing stress, cortisol & sleep
Chronic stress raises cortisol levels, which can further impair insulin sensitivity. If we ignore nervous system regulation and stress management, we’re missing a major piece of the metabolic puzzle.
Sleep is just as important. Getting consistent, high-quality sleep is foundational for improving insulin sensitivity. Even short-term sleep deprivation can worsen insulin resistance and disrupt blood sugar regulation.
4. Targeted supplementation
In some cases, targeted supplements are helpful to support insulin sensitivity and glucose metabolism. These are chosen based on individual presentation and lab findings.
Supplementation is never a replacement for lifestyle change — but it can be supportive when used strategically.
5. Ongoing monitoring
Because insulin resistance can exist before blood sugar becomes abnormal, I often monitor fasting insulin, glucose, and other metabolic markers over time to track improvement.
Why this matters
Improving insulin sensitivity can lead to:
Better energy
Easier weight regulation
Improved hormone balance
Reduced inflammation
Lower long-term risk of diabetes and cardiovascular disease
Insulin resistance does not have to progress. With the right approach, it can be reversed.
Disclaimer:
The information in this article is for educational purposes only and is not intended as medical advice.
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