What is Metabolic Flexibility?
Our health is maintained by complex mechanisms happening in our bodies all the time to maintain homeostasis. These processes function in response to changes in environment and metabolic demand. Metabolic flexibility refers to the body's ability to adapt to changes in metabolic demand. This concept has been used to explain the mechanisms in which the body decides between glucose and fatty acids as fuel for the body. This article provides a primer on Metabolic flexibility and its important role in health and nutrition.
By Stephanie Tucker
What is metabolic flexibility?
Our health is maintained by complex mechanisms happening in our bodies all the time to ensure homeostasis. These processes function in response to changes in environment and metabolic demand. Metabolic flexibility refers to the body's ability to adapt to changes in metabolic demand (Goodpaster & Sparks, 2017). This concept has been used to explain the mechanisms in which the body decides between glucose and fatty acids as fuel for the body.
Metabolic Flexibility in Health
Maintaining metabolic flexibility is crucial for overall health and well-being. When the body can efficiently switch between fuel sources, it helps regulate blood sugar levels, optimize energy production, and support various physiological processes. This adaptability also plays a vital role in metabolic homeostasis and can contribute to reducing the risk of chronic diseases. Metabolic inflexibility or dysfunction has been associated with chronic conditions such as obesity and diabetes (Storlien et al, 2007) (Kelley et al, 1999).
Role of Metabolic Flexibility in Insulin Resistance
Metabolic flexibility is mostly well known because of its implication in insulin resistance. After eating, there is a rapid switch in fuel source, between glucose and fatty acids to prevent hyperglycaemia and allow glucose availability for the brain during fasting (Palmer et al 2022). Insulin resistance, a condition where cells fail to respond properly to insulin, can disrupt metabolic flexibility. When cells become resistant to insulin, it impairs the body's ability to regulate blood sugar levels effectively, leading to elevated glucose levels in the bloodstream. Improving metabolic flexibility can help mitigate insulin resistance by enhancing the body's ability to utilize glucose and fat for energy efficiently (Galgani et al, 2008).
Skeletal muscle accounts for 60 - 80% in glucose response to insulin
How to Measure Metabolic Flexibility in Digital Health Using a Test
Advancements in digital health technology have made it possible to assess metabolic flexibility through various tests and tools. Metabolic flexibility can be used as a biomarker for metabolic health, where a lower metabolic flexibility is associated with excess body weight (Alcantara & Galgani, 2024).
One commonly used method is the oral glucose tolerance test followed by calculating the respiratory quotient (RQ), which measures how effectively the body processes glucose over time. After fasting overnight, plasma glucose levels are tested, and the person receives an oral dose of glucose. Usually after 1 or 2 hours the blood glucose levels are tested again, and the respiratory exchange ratio or respiratory quotient is calculated.
The respiratory quotient (RQ) is the ratio of carbon dioxide produced to oxygen consumed while breathing. It provides insights into which type of fuel (carbohydrates or fats) the body is predominantly using for energy. A lower RQ typically indicates a greater reliance on fat as a fuel source, whereas a higher RQ suggests a predominance of carbohydrate utilization (Smith et al, 2018).
Wearable devices can also be used to measure markers of metabolic flexibility. These devices can monitor various metabolic parameters in real-time, providing continuous data that helps in understanding the body's metabolic responses. For instance, heart rate variability (HRV) reflects the variation in time intervals between heartbeats and is a useful indicator of the autonomic nervous system's activity, which influences metabolic processes.
A higher HRV is generally associated with better metabolic health and flexibility, indicating the body's efficient adaptation to metabolic demands. Certain wearables can also measure ketone levels in the body. Ketones are produced during the breakdown of fats for energy, particularly when carbohydrate intake is low. Monitoring ketone levels can provide insights into the body's ability to switch to fat burning, an essential aspect of metabolic flexibility.
Metabolic Flexibility in Personalized Nutrition
Personalized nutrition considers individual variations in metabolic flexibility to tailor dietary recommendations accordingly. By understanding how different foods impact individual metabolic response, personalized nutrition plans can optimize metabolic flexibility and support overall health goals. Suitable management of calories and nutrients requires good metabolism and the ability to cope with temporary discrepancies in diet quality is important for maintaining overall health and function (van Ommen & Wopereis 2016).
This research aimed to identify whether metabolic flexibility (MetF) indexes were associated with cardiometabolic risk factors before and after adjustment for body size-related factors. The study found that MetF indexes correlated with each other and related to body weight, but were not related to cardiometabolic risk factors except for BMI and HDL-C.
This study investigated the effect of modulating dietary macronutrient composition according to muscle insulin-resistant (MIR) or liver insulin-resistant (LIR) phenotypes on cardiometabolic health. The researchers demonstrated that precision nutrition based on IR phenotype enhances diet-induced health improvements.
Role of Metabolic Flexibility in Weight Loss and Performance
Metabolic flexibility plays a significant role in weight management and athletic performance. When the body can efficiently switch between burning carbohydrates and fats for fuel, it enhances endurance, promotes fat loss, and improves overall exercise capacity by providing the muscles with appropriate fuel. Incorporating strategies to enhance metabolic flexibility can be particularly beneficial for individuals looking to lose weight or optimize athletic performance. The most important aspects to gain and maintain lean muscle as this greatly contributes to metabolic flexibility. For example, based on recent research, adults with low skeletal muscle mass and high adiposity are at greater risk for high glucose, triglycerides, and other biomarkers associated with metabolic health (Wu et al 2021).
Metabolic Flexibility and the Keto Diet
The ketogenic diet is a high-fat, low-carbohydrate eating plan designed to induce a state of ketosis, where the body primarily burns fat for fuel. The keto diet can promote metabolic flexibility by training the body to rely on fat for energy, Nutritional ketosis has been shown to decrease insulin resistance, reduce fasting blood glucose levels and helps to facilitate weight loss (Gershuni et al, 2018). It is important to note the keto diet is not suitable for everyone, especially those with kidney problems, liver disease or high cholesterol.
Current and past Innovators in the Marketplace Measuring Metabolic Flexibility
From wearable sensors to comprehensive metabolic testing platforms, there are multiple companies providing individuals with actionable insights to optimize their metabolic health and performance.
Habit - A US company that uses microbiome testing to create personalized nutrition plans. However in it's hey day, Habit created a solution that included a challenge test which was a milkshake loaded with carbs, fats and protein which a users would have to drink at the beginning of the program. This was followed by blood tests.
Lumen – A small handheld device that measures metabolic fuel usage through exhaled carbon dioxide (CO2) to allow individuals to monitor their metabolic flexibility.
JanuaryAI - Is an app that uses a continuous glucose monitor and activity tracker, to predict the impact of diet on your metabolic health and use this information to help you reduce excessive change in blood glucose levels to improve health and help users lose weight. AI-powered insights allow users access to real time glucose monitoring and predictions.
LSee – A metabolic tracker which analyzes a single drop of blood to measure fat burning in real time after sport or meals. It is for people looking to lose weight to optimize their training and nutrition according to their own metabolism. The tracker works by analyzing a sample of the users blood for glycerol, a fat present in your blood after a meal.
Zoe - A program that helps users understand how food affects their body. It uses at-home tests, food logging, and blood monitoring to provide users with personalised feedback and guidance on what to eat. ZOE uses blood sugar response, fat response, and gut microbiome makeup to guide food choices that reduce dietary inflammation, work with users metabolism, and improve their gut health.
How to Achieve Metabolic Flexibility?
Unfortunately there is no simple answer: achieving metabolic flexibility requires a multifaceted approach that includes regular physical activity, a balanced diet, stress management, and adequate sleep.
How to Improve Metabolic Flexibility
Metabolic flexibility can be enhanced by incorporating a variety of foods, including complex carbohydrates, healthy fats, and lean proteins, prioritizing nutrient-dense foods, minimizing processed and sugary foods. It is also important to engage in regular exercise, manage stress levels, get sufficient sleep, and stay hydrated. Regular physical activity is also just as important as it has been shown to alter fuel storage and availability, a higher mitochondrial capacity in exercise trained skeletal muscle has been associated with enhanced metabolic flexibility (Goodpaster and Sparks 2018). Using tracking tools to measure metabolic flexibility as mentioned above can be a good way to track progress and help individuals recognise what methods work for them.
The Qina Take
Metabolic flexibility is an area that has been growing steadily. A lot has to do with the rise in consumer interest in metabolic health. Whilst the term metabolic flexibility is not exactly rolling off consumers' tongues, consumers do understand that an imbalance can lead to chronic conditions and that not everyone responds to diet and lifestyle in the same way. We believe that metabolic flexibility is important component personalized nutrition and helping consumers to understand their baseline would provide context and reassurance on where they are at. However, testing metaboli flexibility is not cheap, and also not always accessible. We believe with a drive towards prevention the Metabolic flexibility will become part of routine screening and monitoring.
In conclusion, mastering metabolic flexibility is key to optimizing health, performance, and longevity. By understanding its importance, leveraging innovative technologies, and implementing lifestyle strategies, individuals can enhance their metabolic flexibility.
References
- Goodpaster and Sparks 2017 | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5513193/
- Storlien et al, 2007 | https://pubmed.ncbi.nlm.nih.gov/15294056/
- Kelley et al, 1999 | https://journals.physiology.org/doi/full/10.1152/ajpendo.1999.277.6.E1130
- Palmer et al, 2022 | https://www.sciencedirect.com/science/article/pii/S0025619622000428
- Galgani et al, 2008 | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2584808/
- Alcantara and Galgani, 2024 | https://pubmed.ncbi.nlm.nih.gov/38110728/
- van Ommen and Wopereis 2016 | https://pubmed.ncbi.nlm.nih.gov/26764470/
- Gershuni et al, 2018 | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6472268/
- Lumen | https://www.lumen.me/
- JanuaryAI | https://www.hellolingo.com/
- LSee | https://lsee.com/en/
- Wu X., Park S. 2021 | https://pubmed.ncbi.nlm.nih.gov/34069247/