Insulin resistance: what is it all about?

Published on August 19, 2023 | Power supply, Carbohydrates, Diet, Fasting, Metabolism, Obesity, Lifestyle, Sugar

What is insulin resistance?

Insulin resistance is a metabolic condition caused by factors such as a diet rich in processed, carbohydrate-rich foods, a sedentary lifestyle, excess body fat, genetics, and certain hormonal syndromes such as the polycystic ovary syndrome (PCOS) [1].

If uncontrolled, it can progress to pre-diabetes, in which blood sugar levels are higher than normal, and then to type 2 diabetes, metabolic syndrome, nonalcoholic fatty liver disease, and other cardiovascular problems [2-4].

To fully understand insulin resistance, it is necessary to talk about glucose, a simple sugar found naturally in a variety of foods, including starchy vegetables and grains such as corn, rice, potatoes, and wheat, as well as honey and fruits.

Glucose and insulin: partners in energy management

The body breaks down all carbohydrate intake into glucose, its preferred energy source.

We have evolved to depend on glucose because it is the most abundant monosaccharide (simple sugar) in nature and the easiest to convert into energy by the mitochondria, the engines of our cells [6].

In other words, glucose was essential for our survival in the pre-agricultural conditions in which our ancestors lived, where sugary and fatty (high-calorie, energy-rich) foods were scarce and hunter-gatherers sometimes wandered as far as 500 miles to search for food [7, 8].

Before supermarkets existed, our ancestors could spend much of the day with little food before encountering a supply of honey, a bunch of bananas, or another sugary food. To maintain a steady supply of energy, the body needed to store additional calories for the future and evolved to cope by using a hormone called insulin [9].

If we think of energy as money, insulin can be considered the hormone that manages it, in the same way as an investor.

In life, when you receive a sudden influx of money, you decide, based on how much you have and how much you need for current expenses, whether to spend it, put it in a checking account, or put it in a long-term savings account.

In the body, insulin plays a very similar role, directing glucose where it needs to go according to the body's current needs.

Suppose we have just eaten a ripe banana and a sandwich. Here's what happens:

Blood glucose levels rise due to sudden carbohydrate intake.

In response to this biochemical "liquidity injection," the pancreas (an organ near the stomach, liver, and gallbladder) releases insulin, which transports glucose into cells through specialized transporters [10, 11].

The first task of insulin is to transport glucose to cells that need to use it immediately, such as active muscle cells.

But if there is more glucose than the cells need for current "spending" (i.e., if there is more glucose than is needed immediately to be used in the cells), insulin sends the glucose to be stored in a short-term storage molecule called glycogen. Glycogen is like a bank account. It stores energy but is easily broken down to take it out when needed. A small amount of glycogen is stored in muscles and other cells for their use, but most is stored in the liver, where it can be broken down into glucose that is released into the bloodstream for use by all cells in the body, including brain cells.

Once glycogen stores are replenished, the excess glucose that remains in the bloodstream is converted to fat and stored in adipose tissue (fat), which can be regarded as a savings account or a rainy day fund [12]. Although this is natural, accumulating too much fat-particularly visceral fat, in and around organs-increases the risk of developing metabolic syndrome, diabetes, heart disease, and more.

Why is insulin resistance important?

If insulin resistance is not kept under control, it can lead to serious diseases such as type 2 diabetes, atherosclerosis, and nonalcoholic hepatosteatosis (fatty liver) [17-19]. It can also lead to weight gain, which is associated with a number of adverse health outcomes [20].

The immediate effects of insulin resistance can also affect daily performance. Symptoms such as poor sleep, fatigue, and difficulty concentrating are common with insulin resistance and can make one's performance-status difficult [21, 22].

One of the main problems with insulin resistance is that it can trigger a vicious cycle in which cravings for carbohydrate-rich foods develop, compromising metabolic health and further worsening insulin resistance [23]. As we consume more and more carbohydrate-rich foods, glucose levels spike, triggering the pancreas to release additional insulin to bring blood glucose levels back to normal. But because cells do not respond to insulin, you risk getting stuck in a state of elevated glucose and insulin, resulting in weight gain and fat accumulation that is difficult to manage.

What are the causes of insulin resistance?

When we constantly consume a high-glucose diet (an easy feat in the modern world, where we have 24/7 access to processed snacks and drinks), our insulin-based storage system becomes stressed.

In essence, the ability to store glycogen in the muscles and liver is depleted, and excess glucose is converted into fat. While some of this fat may be deposited under the skin (subcutaneous fat), the body also deposits fat around and inside organs that is not visible (visceral fat). Researchers have found that one of the factors contributing to insulin resistance is this type of hidden fat, which is biologically active and can release hormones and inflammatory compounds that promote insulin resistance [13].

The location of fat (subcutaneous or visceral) depends on a number of factors, including genes, birth weight, hormones, and age, but visceral fat is more sensitive to changes in diet and exercise [37]. In other words, consumption of processed and sugar-rich foods and a sedentary lifestyle can increase weight and visceral fat, while a metabolically healthy diet and regular exercise can help metabolize visceral fat.

Because visceral fat is located under the belly muscles and covers the organs (so you cannot pinch it as you would subcutaneous fat), people who do not appear to be overweight may still have unhealthy amounts of visceral fat and exhibit insulin resistance.

Due to hormones and inflammatory compounds released by visceral fat, cells may become increasingly less responsive to insulin in terms of glucose uptake, requiring the pancreas to release more and more insulin to do the same job. When insulin loses its ability to effectively transport glucose to cells and maintain blood glucose levels within normal ranges, insulin resistance develops [13].

It is important to emphasize that not all cases of insulin resistance are related to excessive sugar consumption, and that diet alone is not the only factor behind an incorrect insulin response. Researchers have found that chronic stress, a disturbed gut microbiome, and unrestorative sleep are all associated with an increased risk of developing insulin resistance.

Does the risk of insulin resistance increase with age?

Aging involves a number of physiological changes, some of which are visible (such as wrinkles and graying hair) and some of which are not. In fact, with advancing age comes an increased risk of developing insulin resistance (or reduced insulin sensitivity), whether or not one leads a metabolically healthy lifestyle. In other words, one can do all the "right" things metabolically, but insulin sensitivity may be reduced.

Other aspects of aging are also associated with insulin resistance. Decreased levels of estrogen during menopause, for example, can make cells less responsive to insulin and lead to higher blood glucose levels. In addition, both menopause and andropause (an age-related decline in sex hormones in men) can lead to reduced muscle mass, increased visceral fat, and other changes in body composition that can affect insulin sensitivity.

New research also suggests strong links between insulin resistance in the brain and the development of Alzheimer's disease, which is sometimes called "type 3 diabetes."

What is the relationship between insulin resistance and PCOS?

Insulin resistance is associated with polycystic ovary syndrome, or PCOS. PCOS is a hormonal disorder characterized by the presence of ovarian cysts that can disrupt menstruation and fertility, although it is often accompanied by complications such as insulin resistance, increased risk of cardiovascular problems, increased androgen (male sex hormones) and abdominal fat. Scientists has and that such resistance may in fact contribute to the development of PCOS [33].

What are the signs and symptoms of insulin resistance?

Some people with insulin resistance show obvious signs, such as [14, 15]:

A darkening of the skin around the armpits or neck, known as acanthosis nigricans

Small skin growths (related to the skin) called skin tags or other skin abnormalities

An enlarged waistline ("apple shape").

If the situation has become more severe and you have progressed to hyperglycemia (high blood sugar), you may feel tired and thirsty, with a need to urinate frequently, or hungry even if you have already eaten [16].

Insulin resistance may have unusual or surprising warning signs that are not so obvious, including:

Hair loss, due to elevated blood glucose levels that alter the hair growth cycle and trigger inflammation that impedes blood flow to hair follicles.

Sugar cravings, due to a vicious cycle in which the body's glucose is dysregulated and you start craving sweet things to bring glucose levels back to normal after the crash.

Lethargy and fatigue, due to cells being starved of glucose and unable to use it properly.

The reality is that most people with insulin resistance have no obvious symptoms, which makes it even more important to see the doctor for routine blood tests and to lead a balanced, metabolically healthy lifestyle.

How is insulin resistance diagnosed?

The best way to tell if insulin resistance has developed is to do a blood test.

The three most common tests are:

The fasting glucose and insulin test, which measures glucose levels after at least 12 hours without eating or drinking. The HOMA-index gives us insulin resistance through the calculation: blood glucose x insulin/405.
The oral glucose tolerance test, in which you test fasting plasma glucose, drink a special glucose solution, and measure blood glucose levels every 30 minutes for 2 hours. In these cases, I always prefer to calculate not only the blood glucose but also the insulin value at each blood draw.
A hemoglobin A1C test, which provides a picture of glycemic trends over the past 3 months.

What treatments are available for insulin resistance?

The best way to treat insulin resistance is to make lifestyle changes in relation to diet, exercise, sleep and stress (see below). But your doctor may decide to prescribe metformin, a drug that sensitizes cells to insulin and helps keep blood glucose levels balanced [36]. Metformin, like Ozempic and other GLP-1 agonists, is commonly used for the treatment of type 2 diabetes. It is not explicitly used to treat insulin resistance, but may help improve its symptoms.

How is insulin resistance reversed?

affordable steps to reverse it. The two keys to reversing insulin resistance are (1) improving insulin sensitivity and (2) stabilizing blood glucose levels, paying close attention to the four pillars:

diet,
exercise,
sleep and
stress.

1. Eating a metabolically healthy diet

Nutrition has a powerful effect on insulin resistance. What you eat-and especially when-can help you stabilize blood sugar levels and avoid the glucose roller coaster (the infamous blood sugar spikes resulting in a drop in blood sugar and a feeling of a sweet hunger attack), which can quickly degenerate into reduced insulin sensitivity.

When it comes to building a metabolically healthy plate, fiber consumption is important. Fiber is a great way to lower blood glucose levels and reduce the risk of developing insulin resistance [30].

Other key aspects of a diet that can help reverse insulin resistance:

Eat protein and healthy fats to achieve satiety.
Avoid processed foods and refined sugar
Experiment with mealtimes and intermittent fasting (I recommend skipping dinner)
Avoid a carbohydrate-rich breakfast: the result is less controlled glycemic patterns throughout the day and more hunger. On Mars all milk substitutes and meal replacements. the best breakfast is a fatty protein breakfast.

2. Regular exercise

If diet can help balance glucose levels, exercise is the best way to improve insulin sensitivity. According to one study, even one session of moderate exercise can improve insulin sensitivity for up to 48 hours [35]. Another 2017 study found that even less than one hour of resistance training per week (without additional aerobic exercise) reduces the risk of developing metabolic syndrome [26]. Another group of studies found that 2-3 sessions of resistance training for at least 8 weeks improved insulin sensitivity up to 48% [27].

When exercising, the body "breaks down" glycogen and frees up glucose to be burned during exercise, which in turn frees up "storage" space. This space can be used to store even more glucose during the next carbohydrate-rich meal, instead of forcing insulin to direct it to fat cells.

Although any type of exercise is beneficial for metabolic health, practicing a mix of resistance training and aerobic exercise can help improve body composition and build muscle (which uses more circulating glucose-remember that 80% of circulating glucose ends up in the muscles, as long as there is room for glycogen).

Five of the best exercises for insulin resistance are:

Walking fast
Running
Swimming
Weights
Running

Regarding the time of workout, the best time is when you workout consistently. However, some preliminary research suggests that morning workouts are better for weight loss and concentration/attention, while evening workouts may have a greater effect on metabolic health.

3. Quality sleep

Sleep is critical for insulin sensitivity, glucose level balance, and overall metabolic health. A single night of poor sleep can cause a measurable increase in insulin resistance in healthy people [28]. But good sleep requires certain factors, including the timing and variability of sleep. In other words, not only the time you go to bed and wake up, but also the consistency of your sleep routine.

A 2020 systematic review found that later sleep times and greater sleep variability are associated with increased cardiometabolic risk and other adverse health outcomes [29].

To improve sleep quality, it is important to practice good sleep hygiene. This includes:

Avoid eating (especially carbohydrates) before going to bed.
Keep the room cool, between 15 and 19°C.
Turn off screens at least one hour before bedtime
Take direct sunlight within 2 hours after waking up.
Use blackout curtains or eye masks
Eliminate caffeine after lunch

4. Managing stress

Chronic stress, in which cortisol levels are elevated over a long period of time, can promote insulin resistance and compromise metabolic health. This is partly because cortisol can naturally hinder insulin secretion, although this is not a significant problem in cases of acute, short-term stress [32].

Over time, stress can contribute to the onset of insulin resistance by damaging pancreatic beta cells (responsible for insulin production) and triggering widespread inflammation that worsens insulin resistance. It can also prompt us to make poor metabolic health choices, such as snacking on processed and sweet foods and exercising less, which locks us into a metabolic vicious cycle.

In addition to reducing stress through exercise (even as little as two days a week of aerobic exercise can help reduce anxiety), studies show that mindfulness practices such as meditation can help reduce the physiological response to stress [34].

5. Maintain an appropriate body weight

Insulin resistance can lead to weight gain, which can further worsen insulin resistance, causing a vicious cycle that is difficult to break.

A study of adult women aged 24 to 40 years found that those who had maintained weight loss demonstrated greater insulin sensitivity than the control group with no history of weight loss [24].

On the other hand, women who had previously lost weight but then regained it showed reduced insulin sensitivity. Researchers studying overweight and obese women found that maintaining a 15% reduction in body weight for 12 months improved insulin sensitivity [25].

This does not mean that one cannot lose weight effectively in the presence of insulin resistance, but that when one focuses primarily on reversing insulin resistance (i.e., balancing glucose levels and improving insulin sensitivity), weight loss becomes a natural side effect of the pathway.

How can a CGM help you with insulin resistance?

If the two basic steps to reversing insulin resistance are improving insulin sensitivity and balancing glucose levels, continuous glucose monitoring (CGM) is a powerful tool to help you monitor blood glucose levels consistently and in real time. Monitoring blood glucose levels using CGM combined with an app on your cell phone can provide you with a wide range of information that allows you to make specific, long-term lifestyle changes, many of which can improve insulin sensitivity.

Not only can one learn to identify the foods that trigger glycemic spikes, but one can also understand how one's specific responses to exercise timing, sleep patterns, and periods of stress or inactivity contribute to influencing blood glucose levels and consequently also the insulin response.

Above all, the use of CGM can provide the knowledge needed to combat insulin resistance before it turns into a more serious chronic condition such as type 2 diabetes. Because symptoms of the metabolic disorder often do not appear until it is too late, many people with insulin resistance do not even know they have it.

Basically, what do I recommend you do?

Insulin resistance is a major underlying cause of chronic diseases in our century.

Some practical tips, also to speed up metabolism:

1. Eating protein and fat before carbohydrates does not cause glycemic spikes. Remember that fiber also reduces your glycemic spikes (vegetables). The LOW CARB diet is the ideal approach, especially when combined with the intermittent fasting.

2. Taking a walk after meals can help lower the glycemic response and prevent glycemic spikes: within 90 minutes.

3. High-intensity workouts can actually cause blood glucose to rise due to the liver releasing more glucose to use as energy for the muscles during training, but these increases are not harmful and end up helping to stabilize blood glucose over the long term.

4. Cold therapy is a new technique for post-workout recovery and can help lower blood sugar levels after an intense session.

5. Stress management techniques are important, as we know that chronic, short-term stress causes increased blood sugar levels.

6. The use of apple cider vinegar in water (1 tablespoon) before a meal reduces the glycemic spike.

7. Because weight affects insulin response, achieving an appropriate body weight is crucial.

8. Quality sleep.

In writing the article, I relied on the publication by Claudia S. Copeland, PhD.

Insulin resistance: what is it?