Dr Libby: What Is Metabolic Flexibility & How Can I Improve It?

In this special series, guest writer Dr Libby Weaver shares her health insights.

Are you hearing about metabolic flexibility more? Here’s what you need to know.

Ever wonder why you cruise through some days with a consistency to your energy while other days you hit the wall, sometimes multiple times? Or you might feel like every day you’re flat against that wall. This often boils down to something called metabolic flexibility. It’s a hot topic for a good reason — it’s all about how well your body can switch between using predominantly fat or glucose for fuel.

What is metabolic flexibility?

Our bodies are amazingly adaptive, similar to hybrid cars that run on both electricity and petrol. We are always using a combination of both fat and glucose but right now, what’s your ratio? Is it 50:50? Or 70% glucose and 30% fat? Or vice versa? For example, as you’re reading this, your body is calculating the best energy mix to keep all systems inside you running smoothly — from beating your heart to blinking your eyes. This ability to be able to switch fuels efficiently is key to maintaining energy and feeling great.

Back in 2010, I wrote about this in my first book, Accidentally Overweight, where I explored the body’s decision-making on whether to store fat or burn it, revealing the complex interplay of hormones and metabolic processes involved. More recently diets like keto or intermittent fasting have popularised ways to manipulate this balance. Yet there are numerous ways to support your body to be able to efficiently switch between its fuels that affect many aspects of health beyond body weight.

How does the nervous system affect metabolic flexibility?

The influence of the nervous system on metabolic flexibility is particularly intriguing. One part, called the autonomic nervous system, has two main divisions: the sympathetic nervous system, which is like an emergency response team, and the parasympathetic nervous system, which I like to call the “rest and digest” team. When adrenaline levels are high — perhaps fretting over an earlier disagreement, how much you have to get through in your day or the result of too much caffeine for your body — the sympathetic system tells your body to use glucose for quick energy to get you out of the danger the adrenaline says you’re in. While this is helpful if we need to jump to immediate action, regularly relying on glucose as the predominant fuel to use can lead to sugar cravings and increased fat storage if the real-life scenario doesn’t require physical action like running or fighting. Since most of our stress these days is psychological, it most commonly doesn’t.

What are the risks of developing metabolic disorders like type 2 diabetes?

What are the consequences of poor metabolic flexibility?

The relentless stress that many people experience these days is a major factor that’s messing with our metabolic flexibility. This is why understanding how you think and managing the activation of the sympathetic nervous system through addressing your personal experience of stress, lifestyle changes and how you eat can be crucial for restoring and maintaining metabolic flexibility. Spending more time with your parasympathetic nervous system in charge enables your body to efficiently adapt its fuel usage to match your lifestyle and health needs, promoting overall metabolic health and wellbeing.

Our diets, filled with easy-to-grab ultra-processed foods, also contribute significantly to our loss of metabolic flexibility. It’s a set-up for health troubles down the road, including persistent hunger, insulin resistance and type 2 diabetes. Yet here’s the good news: metabolic flexibility is something you can improve. It’s not about following strict diets that feel more like maths homework or leave you feeling deprived. It’s about smarter, kinder ways to support your body.

How can we improve metabolic flexibility?

Think about managing stress better — one of the most helpful ways to do this is to become incredibly curious about how you think and start to notice if at least some of your stress hormone production is ultimately stemming from worrying about what others think of you. Spend more time basking in the sun, enjoying peaceful sleep and choosing real food over junk. It’s about simple, sustainable habits that will also foster learning and growth. Physical activity is also crucial. It’s not about punishing workouts but about keeping moving in ways that feel good — like walking, yoga or even gardening. Activities that maintain or, preferably, build on your muscle mass can make a major difference to your metabolic flexibility. These activities help your body better manage its energy sources and keep you feeling great.

By understanding and tuning into your body’s signals and needs, you can significantly improve your metabolic flexibility. This doesn’t mean adhering to strict dietary rules unless they genuinely work for and uplift you. Instead, it’s about embracing habits that support your body’s natural processes, ensuring you enjoy life and maintain optimal health. In essence, metabolic flexibility is about more than just physical health; it’s about creating a lifestyle that allows you to thrive in every way. So, take a moment to listen to your body, adjust your habits accordingly and embrace a lifestyle that feels good for you — whatever that looks like.

Dr Libby Weaver PhD is a nutritional biochemist, 13 times best-selling author and international keynote speaker. For more on balancing your hormones, visit Drlibby.com

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