Metabolic Flexibility is the new buzz term in functional medicine! But what does it mean to have a metabolism that’s flexible and why is it so important to you?
Your metabolism works day and night to regulate chemical changes in your body that produce energy, called ATP, for your daily activities and basic life processes like keeping your heart beating, breathing, and digesting. Metabolic flexibility is the ability of your body to respond to these metabolic shifts signaled by an increased or decreased need for energy, and to adjust the fuel source to a preferred source, based on this metabolic demand.1 You may hear it often referred to as the ability to move from a fasting state to a condition of being fed, because in a fasting state, like that of overnight sleep, you should move toward burning fat burning and after a meal you should be burning carbohydrates.
Your body adapts – a built in survival mechanism as we humans evolve over the centuries. Lifestyle habits, multiple snacks filling the space between meals or depriving yourself of fats or carbs over long periods of time can result in metabolic in-flexibility. As you become less flexible, it will become harder for you to shift fuel sources. Instead of using those carbs and fats for fuel, you begin to store the glycogen and fatty acids, leading to insulin resistance, high cholesterol, dysregulated blood sugar and weight gain. And it could be the reason you are craving that next chocolate chip cookie or potato chip.
We do need healthy carbs (and fats) in our diet. If your diet is too low in carbs it is easy to get trapped in a space in between where you are not efficiency burning either fat or carbs, and where you could begin to convert protein into the glucose you need for energy – taking it away from essential metabolic tasks protein is needed for.
Do you ever experience food cravings, mood swings, irritability, anxiety, brain fog, or headaches if you go for too long without eating? Are you eating “healthy” but can’t lose weight? Do you feel fatigued and depleted of energy, even after a good night sleep?
These are all signs that you may be metabolically inflexible, and your metabolism may need some coaching!
In addition to better fuel efficiency, benefits of metabolic flexibility include improved insulin sensitivity, balanced blood sugar levels, increased fat burn, consistent mood and energy levels, optimized workouts, more highly functioning mitochondria, and better overall health. With exercise, good sleep habits, macronutrient manipulation, and intermittent fasting you can get your metabolism back in shape.
Manipulating our macronutrient intake, we can influence the body’s fuel preference. Of course, it is more complex than just reorganizing how and when you eat. There is a whole orchestra of hormones that are taking direction from the foods you eat which influence your metabolism. On low carbs on days with little to no physical activity, look to stimulate the metabolism toward fat burning and on days when you will be exercising, raise carbs around workout times for better performance and metabolic adaptations. During these times nutrient absorption and oxidation will be determined by the hormone pyruvate dehydrogenase (PDH), an orchestra leader in the production of ATP, and GLUT transporters that facilitate the transfer of glucose into cells, an example of how hormones are directing your energy.
Exercise is fundamental. When you exercise, you can burn both fatty acids and glucose at the same time, but the degree to which you do this is individualized. Your working muscles use glucose for fuel and the demand increases with intensity of blood flow and movement. With mild exercise your body will tend to burn more fat, and as intensity increases your muscles will lean toward glucose until with intense exercise, you are primarily burning glucose.2
Sleep helps to regulate the metabolism with its influence on insulin resistance, glucose tolerance and regulation of growth hormone, cortisol, leptin, and ghrelin. It is essential to metabolic flexibility to have healthy sleep habits. Take a deep dive into your relationship with sleep and give it some pillow talk.
Intermittent fasting, or time restricted eating, also helps coach the metabolism since in a fasting state your insulin levels are lower, and your body moves into a fat burning state. Duration, frequency, and timing of your fast is important for its effect on your metabolism. Keep your eating window to daytime hours when you better metabolize food due to your circadian rhythm. Just skipping breakfast is not an efficient way to intermittent fast because you may find yourself eating most of your calories later in the day or at night when it is least efficient for your metabolism.
If you are not sure how to measure your metabolism and best balance your macronutrients, intermittent fast to meet your goals and optimize your health, consider meeting with a nutritionists to discuss your specific needs which are individual and vary depending on your lifestyle, age, energy level and some genetic predispositions.