What is Metabolic Syndrome and Insulin resistance?

Back in 1988, in his paper ‘Role of Insulin Resistance in Human Disease’, Dr Revan described the process of insulin resistance is the start of a process of metabolic dysfunction commonly known as Metabolic Syndrome. 

The primary issue in insulin resistance, is a lack of insulin sensitivity by the cells.

1. In normal metabolism, when you eat foods containing glucose, it enters the bloodstream and the pancreas is signaled to release insulin.

2. Insulin helps glucose enter the muscle, fat and liver cells to use immediately as energy or to store for later use.

3. As glucose leaves the bloodstream and enters the cells the pancreas stops producing insulin.

In insulin resistance, there is hypersecretion of insulin. Over time, the cells in the muscles, fat cells and liver cells do not respond to normal amounts of insulin. They are resistant, not sensitive to insulin. In response the pancreas needs to produce more insulin to continue to maintain normal blood sugars.

Over time the pancreas becomes overworked and less effective at producing these larger quantities of insulin and the body is no longer able to keep blood sugar levels low, resulting in pre-diabetes or diabetes. The higher levels of insulin also are pro-inflammatory and contribute to wider metabolic dysfunction in the body. 

Features of Insulin Resistance and Metabolic Syndrome

There are a number of features which help identify people with metabolic syndrome, which is definition of metabolic syndrome has expanded to include:

1. Abdominal obesity, as seen in a large waist circumference measurement or high waist to hip ratio.

2. Too much sugar (glucose) in your blood.

3. High blood pressure (hypertension).

4. Higher-than-normal amount of fat (triglycerides) in your blood.

5. Lower-than-normal level of “good” cholesterol (HDL).

6. Obesity (BMI>30).

However up to 25% of people with insulin resistance have normal BMI.

What Causes Insulin Resistance?

There are many complex interacting factors that contribute to the development of insulin resistance. These include factors such as:

1. High-simple carbohydrate diet, (such as white breads, pasta, sugar, processed foods containing sugars, high-fructose corn syrup, soda)

2. High fat diets (refined oils, processed foods containing added oils)

3. Alcohol intake,

4. Smoking,

5. Genetic predisposition,

6. Side effects of medications such as atypical antipsychotics.

7. Menopausal status,

8. Lack of physical activity.

9. Jetlag, insomnia, sleep apnoea and shift work

There are also complex social and commercial contributors to insulin resistance and metabolic dysfunction.

1. Colonization of indigenous diets,

2. Displacement of peoples from traditional lands, ways of living and consuming,

3. Poverty

4. Low social support

5. Availability of affordable fresh fruit and vegetables

6. Time-restraints on cooking due to labor participation

7. Town/City planning that determines where fast-food and alcohol is sold.

8. Corporate profit driving pervasive marketing and consumer choice

What Health Conditions Are Associated With Insulin Resistance?

Insulin resistane is the underlying metabolic dysregulation that drives a number of chronic diseases associated. Insulin resistance is a major risk factor for:

1. Type 2 diabetes, 

2. Heart disease,

3. Cancer,

4. Weight gain,

5. Non-alcoholic fatty liver disease (NAFLD),

6. PCOS.

Reversing metabolic syndrome is important as it can reduce the risk of these associated metabolic diseases.

Type II Diabetes and Insulin Resistance

Type 2 diabetes mellitus is the most common form of diabetes. It is estimated that around 90% of all diabetes cases are type 2. In type 2 diabetes, the body initially hypersecretes insulin and is less capable of using the insulin. The point where insulin resistance becomes type 2 diabates is when the pancreas fails to be able to balance blood sugars without medications.

Type 2 diabetes is usually diagnosed in adults over the age of 40. However, it is increasingly being diagnosed in children and adolescents. This is thought to be due to the increasing rates of insulin resistance from earlier ages in these age groups.

Type 2 diabetes is a serious condition that can lead to a number of health complications. These include heart disease, stroke, kidney disease, and blindness.

Metabolic syndrome *which is due to insulin resistance) is a key risk factor in the development of type 2 diabetes in men of normal weight, increased weight or obese, they had an increased risk of diabetes if they had metabolic syndrome (Ärnlöv 2011).

Cancer

Cancer is a disease in which cells in the body grow out of control. Cancer is the second leading cause of death in the United States.

There are many different types of cancer, and each type can develop in almost any part of the body. Metabolic syndrome is a risk factor for several types of cancer. In a systematic review and meta-analysis of 43 studies, they found that men with metabolic syndrome had an increased risk of;

1. liver cancer,

2. bowel cancer,

3. bladder cancer.

It also found that women with metabolic syndrome had an increased risk of;

1. endometrial cancer (cancer of uterus),

2. pancreatic cancer,

3. breast cancer after menopause,

4. rectal cancer,

5. bowel cancer.

Each of these was associated with approximately a 1.5-fold increased risk of developing cancer. The most common type of cancer associated with metabolic syndrome was colorectal cancer.

Heart Disease

Metabolic syndrome is a well-established risk factor for heart disease. In a recent systematic review and meta-analysis found that metabolic syndrome is associated with a 2-fold increase in cardiovascular disease and a 1.5 fold increase in all-cause mortality. They also note that even those without diabetes, maintained a high cardiovascular risk.

Weight and Metabolic Syndrome

Optimal metabolic health is a key component of managing weight. In one study, people who lost 5-10% of their body weight had a significant reduction in the number of conditions associated with metabolic syndrome (Pataky 2018). These included a decrease in blood sugar levels, blood pressure, and waist circumference.

Nonalcoholic Fatty Liver Disease (NAFLD) and Metabolic Syndrome

Nonalcoholic fatty liver disease (NAFLD) is a condition where there is accumulation of excess fat in the liver. This can lead to inflammation and damage to the liver. NAFLD is a common condition, and it is estimated that up to 25% of people in the United States have it. NAFLD can progress to more serious conditions, such as nonalcoholic steatohepatitis (NASH) and cirrhosis or liver failure.

There is a strong link between nonalcoholic fatty liver disease (NAFLD) and metabolic syndrome. NAFLD can both contribute to metabolic syndrome and can also be caused by metabolic syndrome (Wainwright, 2016).

How to Reverse Insulin Resistance

The first step in reversing insulin resistance is to visit your doctor. They can take some baseline measurements and lab tests and can help to identify if you have any of the metabolic conditions associated with insulin resistance. Your doctor can work with you to create a treatment plan.

Modifying lifestyle factors are important improving your metabolic health, reversing metabolic syndrome and reducing risk factors of cardio-metabolic diseases. Your metabolic health plan will likely include lifestyle changes, such as diet and exercise, and medication.

Four lifestyle factors include eating a healthy diet, getting regular exercise, improving sleep and quitting smoking. The four main steps are outline below:

1. Reverse Insulin Resistance: A Pro-Metabolic Diet

A number of studies that have shown the reversing metabolic syndrome can be achieved via modification of diet and these include;

1. Diabetes Prevention Program which treated people with metabolic syndrome with weight reduction of at least 7% of clinical body weight through a healthy low-calorie, low-fat diet and 150 mins of moderate intensity exercise per week. This found reversal of metabolic syndrome in 41 percent of participants who made these lifestyle changes.

2. Participation in group sessions weekly 1-18 of LEARN (Lifestyle, Exercise, Attitudes, Relationships, and Nutrition) Program. Then further group sessions fortnightly in weeks 20-40. Participants lost on average 6.7 kg, reduced blood pressure, cholesterol, triglycerides and cholesterol compared with control group. Balanced diet with energy deficit of 750kcal per day. Diet composition was 30% fat, 50% carb, 20% protein.

These dietary interventions all focused on low calorie diets reflecting previous understanding around metabolic syndrome that was focused on energy balance. However such a low calorie deficit is difficult to maintain long-term. Although it does induce weight loss, it is hard to sustain and many people need healthy ways of eating for longer term health.

Contemporary research on obesity, metabolic syndrome, insulin resistance and the gut microbiome has revealed a much more complex relationship between diet and metabolic syndrome than simply a energy mismatch between intake and output.

When it comes to a healthy diet, there are many different ways to eat. Most importantly are dietary patterns that focus on eating whole foods and avoid colonized diets/processed foods as much as possible. There is a significant body of evidence that demonstrates diets:

1. high in less-healthy plant foods (refined grains, sugars, salty foods),

2. low in healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, tea and coffee) and

3. high in animal foods (animal fat, dairy, eggs, fish/seafood, meat, miscellaneous animal foods) have a higher risk of developing metabolic syndrome (Marrone 2021).

The BROAD Study in 2017 used a plant-based diet intervention in a randomized controlled trial over only 12 weeks. It continued to measure outcomes out to 1 year. It demonstrated significant reductions in BMI, cholesterol, HBA1C (blood sugars) and medication use.

Diets that are whole food based include the Mediterranean diet or a whole food plant-based diet.

Processed foods contain large quantities of added, refined sugars which interfere with insulin signaling, organ function and blood sugar management.

The also contain added fats which when deposited within the pancreas they interfere with insulin production. When deposited in the liver they interfere with glucose regulation.

Processed foods also contain added fats which get deposited in the liver and pancreas and interfere with pancreatic insulin production and liver glucose storage, both of which result in elevated blood sugars.

Western diets high in saturated fats are associated with increased rates of metabolic syndrome. Reducing intakes of cheese, beef, pork, processed meats and high-fat dairy (milks and ice-cream) will dramatically reduce intake of saturated fats (Turner-McGrievy 2014).

Eating lots of vegetables, fruits, legumes, nuts and seeds, is a good place to start. High intakes of fruit and vegetables is associated with reduced rates of metabolic syndrome. Fruit and vegetables also contain a myriad of anti-oxidants that help reduce bodily inflammation.

Fiber intake from whole plant foods reduces and slows down sugar absorption into the bloodstream. It also feeds the gut microbiome with prebiotics that promote an anti-inflammatory diverse gut microbiota that promotes optimal metabolic health. Fiber also improves feelings of fullness.

Most people consuming western/colonized diets consume significantly less fiber than the human body needs (>25g/d for women and >38g/day for men – Turner-McGrievy 2014) .

Replacing animal sources of protein with plant sources of protein, such as beans, dramatically increased the fiber in meals.

2. Exercise and Insulin Resistance

Exercise is important for many reasons, but when it comes to metabolic health, it helps to improve insulin sensitivity and reduce inflammation. Getting at least 30 minutes of moderate intensity exercise per day is a good goal to aim for. Moderate intensity exercise is exercise where you are able to talk but not sing.

In addition to aerobic exercise, muscle strength or resistance training can improve metabolic health because it helps the large muscles become more sensitive to the messaging of insulin (Williams 2007).

Studies have shown reversal of insulin resistance with:

1. walking or jogging 19km per week for 8 months (Johnson 2007) ie 2.7km per day.

2. Supervised resistance training + aerobic exercise 3 days per week for 26 weeks. This included: 1. stretching warm up, 2. Resistance training: 2 sets of 10-15 repetitions per exercise at 50% one rep max. There were 7 exercises performed and once 15 reps could be completed without difficulty, the weight was increased. 3. Aerobic exercise: treadmill, exercise cycle, stair stepper, carried out at 60-90% heart rate. (Stewart 2005).

Additionally sedentary lifestyle is associated with poor metabolic health and increases risk of chronic disease. Studies have shown that 2 minutes of even low intensity walking every 20 mins reduces blood sugar levels and improves metabolic health (Dunstan 2012).

If you have a sedentary job, using a device such as a Fitbit that reminds you to walk 250 steps every hour can be a great way to promote metabolic health.

3. How to Improve Metabolic Health & Insulin Resistance: Sleep Hygiene.

Sleep is often overlooked when it comes to health, but it is important for many reasons, including metabolic health. Getting 7-8 hours of sleep per night is ideal, but if you can’t get that much, aim for at least 6 hours.

There are a few things you can do to improve your sleep hygiene:

1. Keep a regular sleep schedule by going to bed and waking up at the same time every day, including weekends.

2. Avoid caffeine and alcohol for at least 3 hours before bed (or longer if you are more sensitive to the effects).

3. Avoid working or using electronic devices in bed.

4. Avoid blue light for 90 minutes before bedtime.

5. Exercise in the morning or afternoon, but avoid vigorous exercise in the 4 hours prior to bedtime.

6. Have a routine, calming activities that help you wind down before sleep, such as reading, yoga, a bath.

If you snore or are tired when you wake in the mornings after what should have been enough sleep, see your doctor as some people with metabolic syndrome also have sleep apnea. This is an important condition to treat to improve your sleep quality and overall health and quality of life.

Related: How to improve your sleep

4. Quit Smoking For Metabolic Health

Smoking is harmful to your health in many ways, and it is also a risk factor for metabolic syndrome. It also increases risks of heart attacks, strokes and cancer. If you smoke, quitting is one of the best things you can do for your health.

There are many resources available to help you quit smoking, such as nicotine replacement therapy, counseling, and support groups. Additionally there are medications that are very successful in helping people quit smoking such as bupropion and varenicline.

Making lifestyle changes can be difficult, but it is worth it to improve your metabolic health and reduce your risk of cardiometabolic diseases.

Frequently Asked Questions

How Long Does it Take to Reverse Metabolic Syndrome?

As noted above studies that have used diet showed improvements in metabolic health at 3 months. Those using exercise have been successful in reversing metabolic syndrome in only 6 months. Changes to metabolic health on a cellular level occur much sooner.

It is likely that by combining an exercise program with dietary shift to a whole food plant-based diet that changes would create beneficial metabolic shift faster than exercise alone.

How To Insulin Resistance With Diet And Exercise?

In summary, reversing insulin resistance can be achieved with diet and exercise. Supporting your body by moving and eating well help support your metabolic processes.

For long-term health choose a a diet that is whole-food and plant-based, meaning it avoids colonized/processed foods, preferencing whole-grains, fruit, vegetables, nuts, seeds, herbs and spices. It also reduces or eliminates animal product consumption or where animal products are included it opts for leaner options such as chicken, seafood and low-fat dairy.

If you have any questions or would like more information, please consult with your health professional.

Dr Deborah Brunt is a menopause doctor at Rebelle Health and would love to support you through the perimenopause and menopausal stages, supporting all aspects of your health and wellbeing.

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