Insulin resistance is a common condition, affecting up to 24% of adults over 20 years in the US.
Insulin resistance can be described as critical cells in your liver, adipose (fat) and muscle tissue not responding well to insulin. When this happens, they cannot take up glucose from your blood, which is needed for energy.
As a result, the glucose can build up, causing complications. This can lead to further health conditions, including type 2 diabetes.
Risk factors associated with insulin resistance include having metabolic syndrome, being overweight, having pre-existing medical issues, or having a family history of the condition.
Yet, it is worth noting that insulin resistance does not only occur in overweight individuals.
This article will delve a little deeper into what insulin resistance is and how to work toward reversing it.
We will explore the diet and lifestyle factors that can decrease (and increase) your risk of developing insulin resistance.
What is insulin resistance?
Insulin is a hormone produced in your pancreas in the pancreatic beta-cells. Its primary function is to assist glucose in the bloodstream for energy by the cells in your liver, muscle, and adipose tissues (fat tissues).
The glucose in your blood comes mainly from the food we eat, although your liver can also make glucose in times of need, such as during fasting or starvation.
Seeing a rise in your blood glucose levels (also called blood sugar levels) after eating is normal. When your pancreas is functioning well, your liver will release insulin in response to this, to help your blood sugar levels to remain in the normal range (1).
In a state of insulin resistance, the body has difficulty clearing excess glucose in the body’s cells and tissues. This results in a compensatory increase in insulin levels (1,2,3) and leads to something called hyperinsulinemia.
If your pancreas can respond effectively to your bodies’ compromised response to insulin stimulation, your blood glucose levels can remain in the healthy range by producing more insulin.
If, however, measures are not taken to control your blood sugar levels the pancreas becomes overworked.
It is constantly trying to battle with raised blood sugar levels. It does this by producing more insulin. Eventually, the pancreas stops producing enough insulin to control your blood sugar levels, or the insulin it does produce is less effective. This leads to the development of pre-diabetes and, then, commonly, on to type 2 diabetes (1,4).
Risk factors for insulin resistance
There are several risk factors for developing insulin resistance (1). These are divided into modifiable and non-modifiable risk factors.
The modifiable risk factors are those that generally can change or work toward changing if advised to do so. They include:
- Weight. Obesity is a frequent cause of insulin resistance, and it also poses a major risk for type 2 diabetes. When there is abnormal fat deposition within skeletal muscle, this has been identified as an obesity-associated insulin resistance mechanism.
- Hypertension. High blood pressure is a risk factor associated with a higher likelihood of developing insulin resistance. People who have metabolic syndrome, which is a combination of high blood pressure, dyslipidemia (abnormal cholesterol levels), and high waist circumference, are also more likely to have prediabetes.
- Physical inactivity. See the exercise section of this article for more information on how staying active can help to reduce your risk of developing insulin resistance.
Non-modifiable risk factors are those that cannot be altered by the at-risk person. For insulin resistance, non-modifiable risk factors include:
- Age. As we get older, the risk of developing insulin resistance increases. The age at which the risk gets greater varies, depending on the information source, but it is broadly thought to be somewhere above 40 (1,7).
- Ethnicity. People from, but not limited to, the following ethnic groups are more likely to develop insulin resistance and type 2 diabetes.
- African Americans
- American Indians
- Asian Americans
- South and East Asian
- Family history. Insulin resistance is more common among those who have a first-degree relative with the condition.
Other medical conditions are linked with an increased risk of insulin resistance, including:
- gestational diabetes (diabetes in pregnancy)
- heart disease.
In addition, certain medications, including antipsychotics, can increase a person’s risk of becoming insulin resistant. Sleep apnoea can also increase your risk.
Reversing insulin resistance
As with most medical conditions strongly related to diet, there is more than one way to approach treating, managing or even reversing insulin resistance.
While it is possible to do this with lifestyle changes and an insulin resistance diet, it is also important to point out that these methods will not be successful for everyone.
Yet, they may lead to other additional benefits!
Low carb, high protein diet
Low carbohydrate diets have undoubtedly gained popularity over the years. They are frequently cited as an effective approach to weight loss and better glycaemic control in type 2 diabetes.
When thinking about the most popular insulin resistance diet, a low carb, high protein diet is among the most popular to try. Scientific literature also supports their use for improving various factors associated with insulin resistance, such as:
- Reduction in body weight
- Improved insulin sensitivity
- Lower fasting blood sugar levels
- More steady blood sugar levels
However, research also supports the hypothesis that improvements in clinical parameters of insulin resistance, diabetes and pre-diabetes when on a low carbohydrate diet, are due to the weight loss that occurs, rather than the type of diet itself.
In this previously linked randomized controlled trial, fiber intake was also significantly lower among those on a low carbohydrate diet than those on a Mediterranean diet.
There are concerns about the sustainability of low and very low carbohydrate diets in the long-term. More evidence is needed on their safety and efficacy beyond the short-term. Approaches such as the ketogenic diet are quite restrictive and can be challenging to follow.
The ketogenic diet does have a more widely accepted definition, although, as mentioned, it can be challenging to stick to. Various forms of a low carbohydrate diet (including the keto diet) can often be high in saturated fat. Diets high in saturated fat have been linked to abnormal lipid profiles.
Various other dietary approaches were evaluated in an overview of the current scientific reports relating to dietary support in insulin resistance (2019). In addition to a low carbohydrate, high protein diet, these include:
- The DASH diet (Dietary Approaches to Stop Hypertension)
- Low glycaemic index (GI) diet
Each of the above dietary approaches was found to impact the condition of those who have insulin resistance positively. Low carbohydrate diets were found to be effective, although, as already mentioned, there was concern around their sustainability.
A less restrictive approach to reducing carbohydrates (up to 40% rather than as low as 10% energy from carbohydrate) appears to lead to a beneficial effect on insulin homeostasis. This can be achieved by making simple dietary changes, such as:
- Reducing intake of refined carbohydrate by cutting back on fizzy drinks, sugary sauces, desserts, and cereals
- Using less honey and other sweeteners containing sugar
- Reducing your intake of sugary alcoholic drinks
A reduction in portion sizes of refined starchy carbs such as white rice, pasta, and potatoes – replacing with non-starchy vegetables if necessary and choosing wholegrain carbohydrate foods
If you decide to try a low carbohydrate diet, the advice is to seek professional advice from a registered dietitian or nutritionist. As previously mentioned, it is essential to ensure that you are still getting enough fiber, as this can be a concern for people who reduce their carbohydrate intake (6).
Fiber is a type of non-digestible carbohydrate that is essential for good gut health. Most people’s advice is to eat more, and in the UK, the intake is well below the recommended 30g per day.
Fiber can also help regulate blood glucose levels, as it slows the absorption of sugar into the bloodstream. Studies have also found that soluble fiber can help to lower cholesterol levels, having the potential to reduce cardiovascular disease risk.
Soluble and insoluble fibers are the two types of dietary fiber. The following foods are good sources of fiber:
- Beans, pulses, and lentils
- Oats and oat bran
- Nuts and seeds, e.g., linseeds, pumpkin seeds, sunflower seeds, and chia seeds
These nutritious foods are a good source of insoluble fiber:
- Wholemeal bread and cereals
- Some fruit and vegetables
Whilst most foods contain a mix of both soluble and insoluble fiber, they usually contain more of one type.
Regular exercise has been found to be one of the most effective ways of improving insulin sensitivity.
When we exercise, sugar in the blood is more easily moved into the muscles for storage, and insulin sensitivity improvements are seen.
In individuals who are more insulin sensitive, their body is better at utilizing insulin to lower their blood sugar levels. This is important in people who have insulin resistance, as it can lower their risk of developing diabetes.
In this study carried out on overweight men (both with and without diabetes), their insulin sensitivity increased over three months due to taking up resistance training. This benefit was seen regardless of weight loss.
Resistance training includes the following types of exercise:
- Free weights, e.g., using dumbbells or kettlebells.
- Using weighted balls or bags
- Weights machines such as those you frequently find at the gym
- Resistance bands
- You can also use your body weight, e.g., to do squats or push-ups.
It is important to point out that not everyone can carry out resistance exercises. Improvements to insulin sensitivity can also be seen by those who are doing aerobic activities, such as walking, swimming, or cycling.
In this randomized clinical trial, eight weeks of moderate to intensive aerobic exercise effectively affected insulin resistance in those with type 2 diabetes.
It is universally accepted that smoking is bad for your health. Specific to insulin resistance and insulin sensitivity, research tells us that smoking is related to an increased risk of developing diabetes and an increased risk of insulin resistance (9).
Several studies have concluded that nicotine is associated with decreased insulin sensitivity in humans. This, in part, links smoking with insulin resistance.
Seek advice from a Health Care Professional if you would like to get advice and support to stop smoking.
We will all be aware of the effect of losing out on sleep on our mood and outlook. Did you also know that it can harm your health, and more specifically, your blood glucose levels as well?
Sleep apnoea is linked with an increased risk of developing insulin resistance. There is evidence to support this relationship (10), which is thought in part to be related to some key characteristics of sleep apnoea.
Intermittent hypoxia (IH) is one of those key characteristics. IH can mean patterns of oxygen desaturation lasting 15-60 seconds for those with sleep apnoea, followed by a period reoxygenation.
Several studies on rodents have reported that frequent IH encourages insulin resistance and impairs glucose tolerance.
The good news is that the effects can be reduced by improving your sleep routine and catching up on lost rest. Exercise, meditation, and reducing screen time can all have a positive impact on sleep. Speak to a Health Care Professional or visit reputable sites like the Sleep Foundation for more information about improving the quality of your shut-eye.
Intermittent fasting is a hot topic at the moment. It can be defined as an eating pattern where you cycle between periods of eating and fasting.
Examples include the 5:2 diet, whereby you eat a restricted low-calorie diet (around 500 per day) on two days per week, and your usual dietary pattern on the other five days. The advice is to maintain a healthy balanced diet on the days you are not fasting.
Another common example of intermittent fasting is the 16:8 diet. This involves fitting all of your meals and snacks into an eight-hour window during the day. For example, you might choose only to eat between 11 am and 7 pm and fast for hours on either side of those times.
There are different schools of thought surrounding the efficacy of intermittent fasting. If you do not overcompensate by eating more during your non-fasting windows, it is highly likely your calorie intake will go down overall. This will lead to body fat loss. Other scientists have hypothesized that intermittent fasting helps you burn more calories by increasing your metabolic rate.
The explanation for this is that it enhances growth hormone function and increases the hormone production noradrenaline, which promotes the breakdown of body fat to be used for energy.
The studies that support this hypothesis also cite lower insulin levels as a reason for success with intermittent fasting.
Other studies are supporting the benefits of intermittent fasting, which can include:
- Weight loss
- Improved insulin sensitivity and reduced insulin resistance
Despite studies that have shown intermittent fasting benefits, there are also several drawbacks to be aware of. It is not sustainable for everyone, and there are concerns it can lead to a preoccupation with food and an increased risk of disordered eating.
You can achieve a healthy diet more easily by eating regularly – remember that intermittent fasting is not for everyone and should not be considered in those with a history of disordered eating.
Consult a registered nutrition professional if you are interested in finding out more.
You may have heard the following two hormones being mentioned – cortisol and adrenaline. Most people will be aware of adrenaline release, such as when you are doing something that makes you feel excited or nervous. Cortisol, on the other hand, maybe less well known.
Cortisol and adrenaline are both ‘stress-hormones.’ When they are released (in response to a stressful situation), your insulin has a harder time working effectively. This can worsen your insulin sensitivity and lead to insulin resistance.
If stress is longstanding in someone with insulin resistance, it can increase the risk of developing type 2 diabetes and the complications that can arise.
If you have insulin resistance, it is a good idea to consider the stresses in your own life. If you can identify them, you are more likely to be better placed to manage them. Some popular approaches to managing stress include:
- Being physically active
- Mindfulness and meditation
- Steering clear of unhealthy habits, such as excessive drinking and smoking
- Talking to friends, family or a therapist
- Doing something creative, such as writing, drawing or crafts
The NHS has some more evidence-based suggestions for managing stress, which can be found here.
A lack of sleep and stress incidence can often be linked. If you are experiencing both, perhaps consider if they may be linked, and consult a medical professional.
As mentioned above, mindfulness can form part of a strong strategy for reducing your insulin resistance risk.
Meditation can be described as a simple mental technique that can be adopted and learned by people of all ages, backgrounds, beliefs, ethnicities, or cultures. It has well-documented benefits for health and wellbeing (8).
In this study, the researchers looked at the effect of meditation on those with coronary artery disease (CAD, a form of heart disease), strongly linked with insulin resistance and risk of type 2 diabetes. They found that within the group who practiced meditation and mindfulness for 6 months, a significant decrease was seen in CAD’s following clinical parameters:
- Blood glucose levels
- Glycosylated hemoglobin (HbA1C)
- Serum insulin levels
This study’s benefits go beyond the points mentioned above, as the improvement was seen without the need for a significant change in beliefs or stark dietary changes.
If you have insulin resistance, there are various approaches you may wish to try to reverse it. As always, speak to a healthcare professional before making any significant changes to your diet or lifestyle, particularly if you have pre-existing medical conditions.
Risk factors for insulin resistance include metabolic syndrome, family history of the condition, and several non-modifiable risk factors such as age. Dietary and lifestyle changes can help, and it is interesting to consider the benefit that mindfulness and meditation can have on clinical parameters linked to insulin resistance and diabetes risk.