What is Metabolic Flexibility and how do we achieve it?

Metabolic flexibility simply means that the body can switch from using sugar as energy to using stored fat – an evolutionary survival advantage that would have benefited our ancestors in times of food scarcity.

It’s an important biological function and a sign of good metabolic health. So how do we ensure we are metabolically flexible? Natalie and Holly explain.

In a nutshell, the term ‘metabolic flexibility refers to the body’s ability to seamlessly switch between using different energy sources, a bit like a hybrid car. Most cells in the body contain mitochondria that are like battery packs and they are responsible for generating the energy we need for all of our body’s biological processes. 


As with all energy it needs a fuel source and the body’s preferred sources come primarily from carbohydrates (glucose/sugar) and fats (fatty acids), both dietary and stored sources. Whether a cell favours glucose or fats as its primary fuel source will depend on the function of the cell.  

Metabolic flexibility means the body can switch between fuel sources. 


But here’s the thing – the body will use glucose as its primary fuel source when it is present in the bloodstream because it is quicker for the body to turn that into energy than it is for fat to be utilised. This is why carb-heavy diets can make metabolic flexibility challenging.   


Insulin resistance – when things go wrong

Carb-heavy diets lead to a consistent need for insulin. Insulin is a hormone released in response to the presence of glucose in the body. It has a gatekeeper role that facilitates the uptake of glucose for energy by muscle, adipose (fat) and liver. It is an anabolic (building) hormone and when glucose is in excess it converts it to fat for long-term storage.


However, when insulin is consistently elevated (aka insulin resistance) its ability to stimulate cellular glucose uptake becomes compromised and the glucose remains in the bloodstream. The result is twofold, the body releases more insulin to try and get the glucose into the cell and as a last resort it stores excess glucose/sugar in and around our organs – this is called visceral fat.


Note – for people with type 2 diabetes who continue to have prolonged high blood sugars, the demand for insulin over time can exhaust the pancreas and lead to requiring insulin injections as the organ can no longer do its job.

Insulin diagram_ owned by Integral Wellness

A decline in metabolic flexibility means we become metabolically in-flexible – we can only run on sugar and we struggle to make the switch to using fat stores for energy. A key indicator of this is stubborn weight, especially around the middle, that just won’t budge.


There are other signs and symptoms too.

  • Tiredness and feeling unrested when you wake up
  • Cravings and the need for snacks between meals
  • Brain fog and the feeling of walking through treacle each day
  • Getting sick often and taking a while to recover.


These symptoms are the most common and it’s the body’s way of indicating that it cannot effectively turn food and stored energy into fuel – a fundamental biochemical need for us to live well.


Not being able to effectively use multiple energy sources as and when needed, not only impacts our every day but also has a profound effect on our health. We see this played out in metabolic disorders such as type 2 diabetes, metabolic syndrome, non-alcoholic fatty liver disease, cardiovascular disease and so on. 


Want some good news – the loss of metabolic flexibility isn’t permanent! You can take proactive steps to regain flexibility once again.


How to become more metabolically flexible

Reduce reliance on traditional carbohydrates. Bread, pasta, rice – the beige foods that are so commonly in our meals these days need to reduce and make way for fats and proteins.


Eliminate ultra-processed foods (UPFs). These are foods made by factories and things you couldn’t recreate at home. Speaking of which, creating as much as you can at home helps you switch from UPFs to whole foods which is a great step in the right direction.


Don’t be scared of fat. I know Slimming World want you to be but the truth is we need fats for metabolic flexibility and for our hormones (check out our other blogs on hormones).


Stop snacking or grazing your way through the day. Allowing yourself to feel hungry is really key and if you make the switches listed above, the hunger shouldn’t be so strong as your body switches its fuel system. If you keep snacking, it won’t.


Caveat – if you have issues with your gallbladder then this can be harder so our advice is to work with a Nutritional Therapist to address this. Although we can survive without our gallbladder we cannot live as well because our ability to metabolise fats has been compromised so using fats as a fuel source is impacted. This isn’t an ‘end of the road’ issue, there’s plenty that can be done but it’s very specific to your health status so it’s best to book a free call with us and chat it through.

If you’re ready to get metabolically flexible, with or without type 2 diabetes, book your call with a Nutritional Therapist.

Start living life with more energy, vitality and zest than you’ve felt in a long time.