If you haven't read Part 1, click here.
Meet metabolic flexibility, the secret to intermittent fasting.
Metabolic flexibility is the body’s ability to adapt and use whatever fuel is available to it, glucose or fat.
Glucose is the sugar in your blood, the quickest and most available energy form. It's like kindling on fire, it's used up quickly and needs to be replenished frequently to maintain the fire.
Fat is reserved for emergencies when glucose is spent. Fat is a more efficient energy source for your metabolism. It is long-term, sustainable energy, like a slow and steady log on a fire.
So how do we get to the point of using fat for energy instead of glucose?
We need to stop constantly eating. Our high-sugar, high-carb, and never-ending snacking culture can make this difficult, I know. It's these habits that have made us metabolically inflexible, meaning: the inability of our mitochondria to switch between glucose and fat burning to maintain consistent energy levels. This loss of adaptation can leave us shaky, hangry, fatigued, and foggy when we run low on that sugar spike.
To elaborate:
Metabolic inflexibility is a result of:
Blood sugar imbalances
Gut health issues
Leptin resistance
Due to chronic inflammation
Chronic stress and brain dysfunction
Chronic stress alone can slow your metabolism and increase cravings (thanks to cortisol and adrenaline)
Chronic inflammation
The biggest contributor is psychological stress
4 core reasons for increased inflammation
Dairy, sugar, refined grains, and industrial seed oils
Where does intermittent fasting come into play?
Through IF, you can:
Reset your mitochondria to burn fat for fuel
Recharge your metabolism
Renew and repair inflammation
Rebalance your hormones
Here's a look into how intermittent fasting works, as a whole, to gain metabolic flexibility ↓
The 5 key benefits of fasting
Ketosis
A natural metabolic state that takes effect when there's not enough glucose left to burn for fuel
The body uses glycogen from the liver when glucose is spent
When glycogen is gone, the body uses stored fats
The byproduct of fat burn is ketones
When ketones are circulating, your brain can use them as an alternative fuel source
Health benefits of ketosis
Weight loss
Increased energy
Improved mental clarity
Better blood pressure
Improved acne
Lower system-wide inflammation
Curbed food cravings
Reduced seizures in people with epilepsy
Lowered risk of some cancers
Reversed or improved symptoms of PCOS
Improved type 2 diabetes
*** Ketosis can also be achieved through a high fat, moderate protein, and very low carb ratios (the keto diet). However, this diet is very strict and not sustainable for most people.
Hormesis
Good stress challenges your body in a way that is beneficial
Like exercise or cold exposure
Fasting is a form of temporary stress, but in the long term you are increasing adaptability and resiliency at the cellular level
When you fast, your cells enhance their ability to cope under starvation conditions, which makes them healthier and more resilient to disease overall
As long as you don't overdo it, you will become physically stronger in the face of controlled amounts of stress
Autophagy
The cellular clean up crew makes room for new healthy cells
During fasting, the body rids, recycles, or destroys damaged cells and proteins
This improves cellular function, increases the healing of stem cells, and improves resilience against a wide range of stressors including metabolic, oxidative, traumatic, and proteotoxic stressors
This process decreases as we age and it's very important in Alzheimer's Disease prevention!
Fighting inflammation
Fasting decreases inflammation with the 3 above mechanisms by:
Turning off pro-inflammatory cells (monocytes)
Stimulating adiponectin (anti-inflammatory hormone)
Improving insulin sensitivity (lowers inflammatory markers)
Fat loss
As a result of the 4 above mechanisms, fat loss is a byproduct of IF by:
Lowering levels of ghrelin (hunger hormone)
Increasing levels of HGH (a metabolic protein known for maintaining muscle mass)
Although calorie and food restriction is not required with fasting, when decreasing your eating window, you can naturally decrease the food you eat, resulting in weight loss
A study showed that simply limiting one's daily eating window to 10 hours for 3 months can lead to significant weight loss. Participants only ate between 8 am-6 pm and lost 3% of their body weight with a 4% reduction in abdominal fat. They were not asked to change what they ate, but they did organically consume 8.6% fewer calories.
IF also targets belly and visceral fat, slimming the waist
Largely in part of lowered inflammation
To conclude
Some of you that have never heard of IF may think you have to fast for 24 hours to achieve these results. But, no! People saw results with just 10 hours of fasting! This is very attainable and sustainable for busy people like me and you. I personally fast at least 10 hours every day, but 12 hours most days, and occasionally 16-18 hours a couple of times a month. 18 hours may seem like a lot to you know, but after you achieve metabolic flexibility, it seems effortless.
We'll get more into how to start IF in Part 4, but for now, I'm just giving you the basics!
References
Cole, W., & Lidicker, G. (2021). Intuitive fasting: The flexible four-week intermittent fasting plan to recharge your metabolism and renew your health. Yellow Kite.
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