Metabolic Flexibility: Everything You Need to Know to Get Started

In an ever-changing environment, the human body evolved to cleverly control how it uses fuel depending on the food that is available. 

While in today’s modern world, it's a lot easier to predict where your next meal might come from, that wasn't always the case! Metabolic flexibility is the ability your body developed to alter how it uses different types of nutrients for fuel.

When food was not as readily available, metabolic flexibility allowed the body to limit the impact of going long periods without eating. However, easy access to high-calorie processed foods combined with physically inactive lifestyles may directly impact your ability to be metabolically flexible. 

But having that metabolic flexibility can be helpful so that you can feel your best and live a healthy lifestyle. Let's explore what metabolic flexibility really means and how it affects overall wellness. 

What is Metabolic Flexibility?

When you are metabolically flexible, it can become easier for your body to switch between fuel sources to maximize efficiency. In other words, if you have good metabolic flexibility, your body is able to more efficiently use the fuel from different macronutrient sources such as carbs and fats.

When you go long periods without food, your body makes a number of internal adjustments, shifting gears to rely on different fuel sources, such as glycogen breakdown, protein breakdown for glucose, and fatty acid oxidation.

Though more research is needed, some early studies suggest that metabolic flexibility can be associated with certain aspects of a healthier lifestyle, such as: 

• Better weight maintenance
• Increased energy levels
• Lower odds of developing a metabolic disease
• More consistent, healthy glucose levels
• Improved sleep
• Optimized workout performance

Metabolic Flexibility vs. Metabolic Health vs. Metabolism

Terms like “metabolism” and “metabolic health” can be difficult to understand at first glance. But they play a major part in understanding metabolic flexibility. 

Once you learn the role they play, it’s easier to understand the impact they have on your overall well being and a healthy lifestyle.

What is Metabolism?

Metabolism describes all the chemical processes that take place in your body to keep you alive. These chemical processes break down into two main categories:

• Anabolism is the process of building and storing. An example of anabolism is when your body takes the food you eat and uses it to build organs, bone, or muscle. This process can also involve building proteins from smaller amino acid units, building glucose from carbon dioxide molecules, and building lipids from fatty acids joined with glycerol molecules. Your body uses these larger molecules to maintain body tissues, grow new cells, or store energy. It also takes energy for these anabolic processes to work. 

• Catabolism is the opposite, breaking down tissues and energy stores. Catabolic processes break down proteins, carbohydrates, and lipids to release energy. 

The process of energy metabolism involves generating ATP from nutrients. ATP is adenosine triphosphate and it is often considered the "energy currency" of the cell. 

The balance between energy intake and energy expenditure determines energy stores. Your energy metabolism works in your body every minute of every day. It’s at the very root of your body’s ability to survive. But, it may not be working as efficiently as possible. 

Metabolic Rate and Metabolism

Your basal metabolic rate (BMR) is the number of calories your body burns when at rest. Many factors can affect BMR, including: 

• Age
• Hormones
• Genetics
• Body weight
• Body composition (body fat/muscle ratio)
• Physical activity
• Sleep patterns
• Stress

The efficiency of your metabolic rate may affect your metabolic flexibility and wellness. Healthy lifestyle decisions related to your diet, sleep routine, stress management, and physical activity may help metabolic processes work effectively. 

But just as you have to work at being physically fit, you have to work at being metabolically fit. The right lifestyle choices can help support good metabolic health, and this may include improved metabolic flexibility.

What is Metabolic Health? 

There is no standard definition of metabolic health. Scientists generally describe it as the absence of metabolic syndrome. Many researchers express concern over the current limited definition of metabolic health and the way they may have limited predictive relevance.

According to a recent study published in the journal Current Hypertension Reports, metabolic syndrome affects approximately one-third of adults in the United States. 

Five conditions may contribute to metabolic syndrome: 

• High blood pressure
• High blood sugar
• Abdominal obesity
• Abnormal cholesterol
• High triglyceride levels

Having three or more of these risk factors may lead to a metabolic syndrome diagnosis. If all five are present, it greatly increases the chance of developing heart disease, diabetes mellitus, and stroke.  

The main factors that can lead to metabolic syndrome (being metabolically unhealthy) include physical inactivity, being overweight, age, poor diet, and genetics. To learn more about metabolic health, check out these books recommended by the Nutrisense Dietitian team.

Differences Between Metabolic Health & Metabolic Flexibility

Metabolic flexibility is one aspect of metabolic health. When your body becomes metabolically inflexible, problems like hyperglycemia can arise and affect your metabolic health and wellness. 

Why Metabolic Flexibility can be Important for Glucose Levels 

Metabolic Flexibility Means Better Energy Efficiency

If you are metabolically inflexible, your glucose levels are more likely to rise higher than normal and stay higher for longer than they should in certain situations. Metabolic flexibility allows for improved energy efficiency, including supporting optimal glucose regulation and energy metabolism.

Connection between Metabolic Flexibility and Insulin Resistance

The best example of compromised metabolic flexibility is insulin resistance. Remember, when you’re metabolically inflexible, you are more likely to experience reduced glucose oxidation.

If you continue to have these high glucose levels long-term, your pancreas has to produce more insulin to manage the increase. The cells that make insulin in your pancreas then become overworked and dysfunctional. 

Over time, your cells start to ignore the persistent insulin signal and stop removing the excess glucose from your blood. Impaired insulin-stimulated glucose metabolism is linked to diabetes mellitus.

This insulin resistance can lead to long-term health problems.

Potential Effects of Metabolic Inflexibility on Insulin Resistance 

There are several long-term health effects that result from metabolic inflexibility and insulin resistance:

• Insulin resistance and long-term inflexibility can increase your risk of developing type 2 diabetes, high blood pressure, and high cholesterol. 
• Your body's ability to use its fat stores may become impaired, leading to weight gain and obesity. 
• When you become insulin resistant, it alters the mass, structure, and function of the mitochondria in your cells. Mitochondria (the powerhouse of your cells) then have to work harder, producing more by-products called free radicals. Too many free radicals in your body can trigger illnesses like cardiovascular disease or cancer. 

Better Metabolic Flexibility = Reduced Micromanagement

Metabolic flexibility and glucose homeostasis are intertwined. That’s why understanding your body’s glucose response is important for supporting metabolic flexibility as part of a healthy lifestyle. 

Steps to Exploring Your Metabolic Flexibility

If you want to learn more about your body’s metabolic flexibility, here is a guide on how to get started:

1) Track your Glucose

It’s challenging to know what is happening to your glucose levels unless you actively track them. You can’t physically see what foods make your glucose levels spike and put a strain on your cells. 

The only way to track your glucose in real-time is to use a continuous glucose monitor (CGM). It lets you actively see which lifestyle influences and foods directly impact your glucose levels.

Armed with this knowledge, you can make simple yet effective lifestyle changes for better metabolic health. It also allows you to experiment with foods to ensure you find a nutrition plan personalized to your individual body reactions.

2) Focus on your Diet

Diet can affect your metabolic flexibility. Remember the phrase, “you can’t outrun a bad diet.” 

Even with regular exercise, a bad diet can put stress on your body at a cellular level. Eating nutrient-dense whole foods with plenty of fiber and avoiding processed foods is the best place to start.

• Avoid the Standard American Diet 

The standard American diet contains excess sodium, refined grains, processed vegetable oils, and added sugars and can lack important vitamins and minerals. This contributes to the fact that over half of all American adults have one or more preventable chronic diseases. 

To improve metabolic flexibility, you may want to focus on whole foods and minimize your added sugar and refined carbohydrate intake.

This can help to:

• Reduce your glucose and insulin levels
• Put less stress on your cells
• Improve metabolism
• Improve metabolic health 

• Consider Teaming Up with a Qualified Nutrition Professional

If you’re already thinking about changing your diet or starting a new one, working with a credentialed dietitian or nutritionist may be beneficial. Each individual may have unique dietary needs and respond differently to certain eating patterns.

A dietitian can customize different dietary experiments to help you find what works best for you based on your unique body and medical history.

• Eat Within your Energy Requirements

Overeating and excess energy intake, regardless of the food, can lead to inflexibility. Extra calories can lead to excess glucose, which may lead to insulin resistance and fat storage. 

Ensuring you eat within your energy requirements may reduce this risk and can improve metabolic flexibility. 

3) Get Appropriate Exercise

Physical inactivity is one of the leading causes of metabolic inflexibility. Exercise is key in fighting this because it helps control glucose levels. 

Studies show that there are many positive effects of exercise, such as increased mitochondrial content, improved glycemic control, and improved insulin sensitivity. Improving insulin sensitivity helps your body maintain healthy glucose levels. 

Trying different types of workouts in your exercise routine can also assist your body to become more metabolically flexible.

Any type of exercise is beneficial and can increase your energy expenditure. But, experts believe that incorporating a mix of moderate to high-intensity aerobic cardio (zone 2 heart rate training—60 to 70 percent of heart rate max) and strength training gives optimal results. Zone 2 training improves mitochondrial function while strength training may improve insulin sensitivity and glucose management.

Regardless of the type of exercise, regular muscle activation stands as a frequently recommended preventative measure against developing metabolic disease. 

4) Get Enough Rest and Repair

The connection between sleep, stress, and metabolic health is a popular topic in clinical research. Sleep deprivation can lead to chronic health problems such as diabetes or an increased risk of cardiovascular disease. 

Both the quality and length of sleep are essential to metabolic health. Even partial sleep deprivation can lead to insulin resistance in an otherwise healthy person. 

In fact, poor sleep can:

• Affect hormone levels (lowering leptin increasing ghrelin)
• Increase inflammation in the body
• Promote insulin resistance
• Increase risk for chronic health problems
• Increase weight gain

So, good sleep hygiene is a key part of improving metabolic flexibility. This goes hand in hand with managing stress, which has a very similar impact on your metabolic health.

Stress causes your body to release hormones such as adrenaline and cortisol. When facing a “fight or flight” stress response, our bodies release glucose to provide the extra energy required to deal with the situation. 

Chronic stress may cause many changes in how your body processes glucose, even leading to hyperglycemia or even more reactive hypoglycemia. That built up glucose may increase risk for long-term conditions like diabetes.

Taking steps to reduce stress and improve sleep may support healthy glucose regulation, positively affecting metabolic flexibility. 

Why Glucose Monitoring is Important for Metabolic Flexibility

As you can see, there are links between glucose, metabolic flexibility, and metabolic health. High glucose levels are not always linked to diabetes, though having high glucose levels may lead to other adverse effects. Monitoring your glucose levels can make it easier to build healthier habits and improve your overall well being.

How Can You Monitor Your Glucose Levels?

A CGM gives you the ability to track glucose in real-time. Glucose monitoring provides biometric data that empowers you to understand what your body needs to live a healthy lifestyle. 

There is no “one size fits all” approach to achieving metabolic flexibility. Everyone has a different genetic makeup and response to external factors. 

Using a CGM to can allow you to:

• See in real-time how your body responds to food, drink, exercise, sleep, and stress
• Try experiments to find what works best for your body’s specific needs
• Actively track changes in your glucose levels
• Make lifestyle changes based on data for a healthier lifestyle