Insulin is the hormone your pancreas releases after you eat; it signals an abundance of energy in the body. Insulin lowers blood glucose by increasing its uptake and storage in tissues. Muscles take up 60–70%, the liver about 30%, and fat tissue around 10% of sugar from the blood [3, 1, 2].
What is HOMA-IR?
HOMA-IR (Homeostatic Model Assessment of Insulin Resistance) tells you how much insulin your pancreas needs to make to control your glucose levels .
HOMA-IR was developed in the 80s and is an indirect measure: it is calculated from your fasting glucose and fasting insulin levels. While it might not be the best model, it is still the most widely used one in clinical research [5, 6, 7].
Different studies provide slightly different ranges for HOMA-IR. But they all agree that the higher your HOMA-IR gets, the more insulin resistant you are.
Generally, you have optimal insulin sensitivity if your HOMA-IR is less than 1. Levels above 1.9 signal early insulin resistance, while levels above 2.9 signal significant insulin resistance.
If your HOMA-IR is high, your body is using more insulin than normal to keep your blood sugar in balance. The higher the number, the more resistant you are to insulin.
Insulin resistance is one of the symptoms of metabolic syndrome and an early stage in developing type 2 diabetes.
In most “healthy” people, insulin resistance is mainly caused by two factors: overeating and lack of physical activity. Eating too much and being inactive can cause a buildup of fat in the liver and muscles, which makes these tissues less responsive to insulin .
Other causes of insulin resistance include stress, pregnancy, and various disorders and diseases.
1) Overeating/Nutrient Excess
When 6 healthy men were fed a diet of over 6,000 kcal/day, they gained 3.5 kg on average in a week and developed insulin resistance after only 2 – 3 days .
Palm oil, which is high in saturated fat, increased insulin resistance by 25% in 14 people (15% in the liver and 34% in fat tissue) .
However, not all fat tissue is created equal. While the amount of fat in the body does correlate with insulin resistance, how that fat is distributed is more important.
Fat around your internal organs, also known as belly fat or visceral fat, increases your risk of insulin resistance and type 2 diabetes. Fat underneath the skin, known as subcutaneous fat, decreases the risk [2, 15].
3) Sedentary Lifestyle/ Physical Inactivity
Early insulin resistance occurs rapidly after short-term physical inactivity (1-7 days). Inactive muscles are probably the primary cause, but the exact mechanism is still unclear .
In a study of over 3k children, lower physical activity was associated with higher HOMA-IR .
Sitting for long periods of time without getting up was linked to higher insulin resistance in a review of 3 studies with a total of 62 people. The higher the insulin resistance, the more the people benefit from interrupting long sitting periods with regular, brief activity breaks .
Work-related stress was associated with increased HOMA-IR in another study of 366 patients with PCOS and 325 controls. Additionally, higher HOMA-IR increased the risk of PCOS .
Stress also causes insulin resistance in severe illness .
5) Not Enough or Too Much Sleep
Most people need 7-8 h of sleep per night for optimal health. Getting more or less than you need may be detrimental. For example, both shorter and longer sleep duration were associated with higher insulin levels in over 2.8k people [23, 24].
In 245 high school students, those who slept less during the night had higher HOMA-IR .
In the short term, lack of sleep increases blood sugar levels by activating the stress HPA axis and increasing cortisol. In the long term, chronic sleep deprivation triggers insulin resistance [3, 26, 23, 27].
In 5.8k people, excessive daytime napping was linked with higher HOMA-IR .
6) Sleep Apnea
According to a meta-analysis of 16 studies, people with sleep apnea have higher HOMA-IR than healthy people .
That is why some initially obese individuals can develop diabetes on crash diets when they adopt strenuous weight-reduction regimens .
8) Muscle Damage Due To Exercise
But this isn’t the case if you exercise too much or incorrectly, which can both cause muscle damage and inflammation .
Muscle damage is typical after eccentric repetitive activity such as running or walking downhill. Your muscles are suddenly forced to stay contracted over an extended period of time .
When 12 healthy women ran downhill for 45 minutes, their insulin and HOMA-IR levels went up and stayed high throughout the recovery period of 1-4 days .
This doesn’t mean you shouldn’t run, but racing downhill for almost an hour is not the best idea. Make sure your exercise regimen is diverse enough and not overly vigorous.
9) Hypothyroidism and Hyperthyroidism
Thyroid hormones are important for metabolism and blood sugar control.
Both high (hyperthyroidism) and low (hypothyroidism) thyroid hormone levels disrupt insulin function. In hyperthyroidism, insulin resistance in the liver disrupts glucose balance; in hypothyroidism, the culprit is insulin resistance in the muscles and fat tissues [41, 42, 43].
Insulin resistance increases during the course of a normal pregnancy, reaching its peak in the third trimester .
In excess, insulin resistance in pregnancy can lead to gestational diabetes .
In addition, insulin resistance can spike in subsequent pregnancies. Insulin levels and HOMA-IR increased with multiple pregnancies in a study that compared 100 women in their first pregnancy and 100 women with multiple pregnancies .
Compounds called persistent organic pollutants (POPs) can contribute to the development of insulin resistance and type 2 diabetes .
POPs can be found in pesticides, insecticides, fungicides, flame retardants, paint, plastics (PCBs), etc.
In a large study of 2k adults, diabetes was strongly associated with higher blood levels of six different POPs .
How do we know this? People who develop insulin resistance often have a history of type 2 diabetes in their family .
In addition, certain populations are more at risk than others. In the US, black Americans and Pima Indians have a higher risk of insulin resistance than whites. In Asia, Indian and Chinese are at high risk of insulin resistance .
This is, in part, because people get more belly fat and become less active as they age. Additionally, your energy requirements decrease as you age, making overeating more likely. But additional factors, such as increased oxidative stress and impaired mitochondrial function, may also play a role [30, 8].
14) Diseases of the Pancreas
15) Hormonal Disorders
Hormonal disorders can disrupt glucose balance.
Insulin also increases in Cushing’s syndrome, due to the excess of cortisol .
16) Other (Rare Disorders)
Insulin resistance is a major feature of rare disorders, such as :
- Down’s Syndrome
- Turner’s Syndrome
- Klinefelter’s Syndrome
- Myotonic dystrophy
- Friedrich’s ataxia
- Laurence-Moon-Biedel syndrome
- Glycogen storage diseases type I & III
- Mitochondrial disorders
- Metabolic syndrome (including high blood pressure and high cholesterol)
- Heart disease
- Liver disease
- Polycystic ovary syndrome (PCOS)
The major consequence of insulin resistance is eventually developing type 2 diabetes.
Insulin resistance precedes the development of diabetes by 10 to 15 years .
2) Metabolic Syndrome
- High blood pressure
- High blood sugar
- Excess belly fat
- High bad cholesterol/low good cholesterol
- High triglycerides
In a study with over 2,300 people, those with higher insulin resistance at baseline had more than a 5 times greater risk of developing metabolic syndrome 5 years later .
In another study that monitored 3,400 people over 20 years, those with the highest insulin levels and HOMA-IR had a much greater risk of eventually developing high blood pressure .
3) Heart Disease
According to a meta-analysis of 9 studies with over 22,000 people, those with higher fasting insulin were at an increased risk of heart disease .
In addition, in a study that followed 2,500 people over 20 years, those with the highest HOMA-IR values had an almost 70% higher risk of dying of heart disease compared to those with low HOMA-IR levels .
4) Fatty Liver
Polycystic ovary syndrome (PCOS) is the most common hormone disorder of premenopausal women.
Insulin resistance can precede PCOS and contributes to its development by causing a disbalance in sex hormones .
7) Cognitive Decline
In 1,416 mid-life nurses, higher insulin levels were associated with a faster cognitive decline and worse verbal memory after 10+ years .
In a study of 351 people, higher HOMA-IR was related to subsequent poorer cognitive performance and greater cognitive decline .
Ways To Decrease HOMA-IR
- Improving your nutrition: reduce the amount of overall calories in your meals, eat more fiber and less processed carbs
- Becoming more active: get plenty of exercise and taking regular active breaks from prolonged sitting. Be persistent, but don’t overdo it!
1) Fasting/Calorie Restriction
While there is a belief that high sugar intake contributes to diabetes, studies now suggest that sugar is bad only as it contributes to excessive energy intake in general .
If you are baffled or frustrated by the prospect of counting calories, don’t despair. Intermittent fasting and alternate day fasting can also help decrease insulin resistance and are promising strategies for diabetes prevention [72, 73, 74].
2) Fruits and Vegetables
While the number of calories you consume is important, where those calories come from also matters.
In 418 non-diabetic people, following the Mediterranean diet for 4 years lowered diabetes risk by 50%, compared to a low-fat diet .
In 72 diabetics, a vegetarian calorie-restricted diet improved insulin sensitivity better than the conventional omnivore version after for 6 months .
Why are plant-based foods beneficial? Studies suggest protein, and especially branched-chain amino acids (BCAA), worsen insulin resistance .
A study in 15 postmenopausal women revealed that even partly replacing meat with soy in a moderately high-protein diet improved insulin sensitivity .
In another study with almost 5,5k people, those who ate more whole grains had lower insulin resistance, less inflammation, and lower chances of getting diabetes .
Adding more fiber to your diet can improve your HOMA-IR pretty fast. 12 weeks of supplementation with soluble fiber was enough to effectively lower insulin resistance in a study with 120 overweight men .
4) Weight Loss
Calorie restriction works when it comes to insulin resistance because it helps you lose weight – especially belly fat.
In a study with 56 women, those who successfully lost weight had better insulin sensitivity than those who regained it. Weight loss itself was the strongest predictor of improved insulin sensitivity .
Gastric bypass resolves type 2 diabetes in approximately 80% of patients !
Weight loss doesn’t have to be radical to be effective. In 2 studies with 48 obese and 8 diabetic people, respectively, gradual loss of 5 – 8% body fat was enough to lower belly and liver fat as well as insulin resistance [92, 15].
According to a meta-analysis of 11 studies with 846 diabetics, exercise was effective in decreasing insulin levels and lowering insulin resistance .
But is the type of physical activity important?
According to a study in 1229 people, leisure-time physical activity is beneficial for HOMA-IR, while occupational and household physical activities are not. And, as mentioned, strenuous eccentric exercises like running downhill do more harm than good .
Get enough good-quality sleep. This will help decrease insulin and blood sugar levels.
In a study of 245 high school students, shorter sleep was associated with higher HOMA-IR .
Similarly, in 280 adolescents, poor sleep quality was related to a greater HOMA-IR .
Take time to deal with the stress in your life. Any activity that helps you unwind and decreases your cortisol levels will have a beneficial effect on your insulin levels – whether it’s a relaxation technique, meditation, yoga, exercise, a hobby, or simply having fun.
8) Deal with Infections and Inflammation
If you are suffering from infections and/or inflammation, those may be contributing to your insulin resistance .
In addition, in 370 patients, HOMA-IR decreased with successful eradication of H. pylori .
Another culprit that can increase your insulin resistance without you knowing it is gum inflammation (periodontitis). Proper dental hygiene and regular visits to the dentist are important for your overall metabolic health. Treating gum disease reduces insulin resistance in diabetics .
Adding the following supplements to your diet can help lower HOMA-IR:
- Cinnamon [107, 108]
- Ginkgo biloba 
- Green tea extract [110, 111]
- Ginger 
- Broccoli sprouts 
- Beta-carotene 
- Cocoa/dark chocolate [115, 116]
- Fenugreek 
- Grape seed oil 
- Flaxseed 
- Nuts – including pistachios, walnuts, almonds, and hazelnuts [120, 121, 122]
- Vitamin D [123, 124, 125, 126]
- Magnesium [127, 128, 129, 130]
- Zinc [131, 132, 133]
- Chromium [134, 135]
- Alpha-lipoic acid 
- L-Carnitine 
- Histidine 
- Arginine 
- CoQ10 
- Resistant starch 
- Probiotics and synbiotics (probiotics + fiber) [142, 143, 144, 145, 146]
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HOMA-IR is an important measure of insulin resistance. It is not measured directly in the blood but is calculated from your fasting blood sugar and insulin levels.
You produce too much insulin when your cells no longer respond to it, which can lead to type 2 diabetes and a number of other chronic diseases. In that case, your HOMA-IR score will be high. The higher your score gets, the more problematic your insulin resistance is.
The main causes of insulin resistance and high HOMA-IR are overeating and being inactive. You need to change your diet and lifestyle to get your scores down.
Aim to engage in light exercise every day. Try to interrupt your sedentary routine by getting up from time to time. You should also reduce your calorie count or try intermittent fasting.
Eating more fiber and vegetables can also help lower your HOMA-IR. Additionally, make sure your lifestyle is not stressing you out or disrupting your sleep. Lastly, look to resolve any underlying infections with your doctor.