What is metabolic flexibility?
"Due to possible discontinuities in both the supply and demand for energy, humans need a clear capacity to use lipid and carbohydrate fuels and transition between them.(1)"
This capacity is a healthy state called metabolic flexibility.
In English, metabolic flexibility is the ability to switch from one fuel source to the next; from fats to carbs and carbs to fat.
Metabolic inflexibility is just the opposite; the inability (or limited ability) to switch from one fuel source to the other.
How does Insulin impact?
There are many hormones in the body which affect your body's composition and moods. A key to understanding metabolic flexibility is the vital role the hormone insulin plays.
In a healthy state with normal insulin metabolism, humans can effectively switch from a primarily fat metabolism to a carbohydrate metabolism, and vice versa.
For instance, having more muscle mass mean that more energy is exerted at rest to maintain the same amount of mass than fat. Furthermore, both storage capacity of glycogen and lipids and your level of insulin sensitivity are affected.
Key Information to Know about Insulin
All foods result in the release of insulin.
Insulin is the fuel selector switch.
When levels of insulin are low, the body is in fat burning mode.
When insulin is high, the body is shifted towards carbohydrate metabolism (and fat storing mode).
Throughout the day, our insulin levels go up and down in peaks and troves until we go to sleep. During the hours of the night, our insulin levels are at their lowest which makes it the time when we are most likely to burn fat.
How to know and test if you’re metabolically flexible?
“1 – High Insulin
If you feel like collapsing face-down in your drink and spilling it all over the table, you probably have an issue with high levels of insulin and the resulting crash from it.
If you feel great, no worries.
*These are the opinions of Mike T Nelson. Before doing any changes to your diet, consult a nutritionist first.
How to eat and train to become metabolically flexible?
The key to becoming metabolically flexible are timings and diet/nutrition. Both are as important as each other when it comes to fat burning.
If you did a high-intensity workout such as sprints and power session, increasing your intake of protein and carbs before and the after session will give you an increased level of insulin. The body is then able to utilize the carbohydrates better, giving you a better output in performance.
If the next day you were to do low-level aerobic training. It may be beneficial to do it fasted. When doing slower, workouts for a longer period of time, the body's best source of energy is fat.
By doing this you are matching your fuel to the intensity and maximizing your fuel sources. The benefits to being very metabolically flexible are when you come to competition, you will be able to maintain performance without flag lining.
What should your macro split be to be the most efficient?
For an active person, i.e. does high-intensity training 3 - 4 times a week
0.75 grams per lb of body weight (total body mass) to 1.5 max
60 - 80g Fat
20g carbohydrates with 20g protein pre and post workout
Adjust Carbohydrates to be losing fat whilst still maintain performance
Recommended to increase protein if cutting carbs to lower end and vice versa. However, as noted, having a low carbohydrate level for a high-intensity training have been shown to be less beneficial.
For instance, a 140lb (10st or 65kg) person this would equate to:
105g - 200g P | 60g - 80g F | 105g - 200g C
How to maximize your Metabolic Flexibility?
Eat more protein
Numerous studies have shown that in a calorie deficit, 0.75g per lb of body weight was the minimum. Body builders have shown to increase protein to up to 1.5lb per body weight. This method should only be used for a short period of time as you want to do the minimal Effective Amount (mEA). Work by Devkota S et al. (2) showed that replacing carbs with protein was beneficial in shifting molecular activity in muscle vs. fat; which should improve body composition (more muscle, less fat).
Like most of us (including myself) tend to eat the same things day in and day out.
Having more variety in your life allows you to feed your body with a huge array of micronutrients. These are critical for health, performance and most importantly, prevents OVERexposure to any one particular item or toxin too!
Add In a Fast
By fasting, exercising on an empty stomach. Fasted cardio has been shown to burn more fat during the session. It has also been shown, that during a fasting condition, insulin levels are low, pushing the body towards more direct fat utilization (burning).
The later is the best form to increase metabolic flexibility as studies have shown to be easiest strategy to maintain and have the quickest recovery time compared to more complex methods.
Author: Charleh Dickinson
Disclaimer: Please note that we are not a professionally qualified Doctor, Dietician or Nutritionist. The information on our blogs are based only on my own experiences and the research we have found in academia.
If you are interested in changing your diet we would highly recommend doing so under the care of a qualified Health Professional. We firmly believe that there is a no diet that suits everybody. You have to go out there and discover it for yourself and enjoy the journey along the way.