Why is fasting fast becoming the tool of choice for improving energy, reducing inflammation, increasing focus, mental clarity, mood, improving sleep, stabilising blood sugar, preserving lean muscle mass, increasing metabolism and helping to normalise appetite?
In recent times, fasting has garnered much attention for it’s ability to affect multiple aspects of our health. The vast beneficial effects all come down to a specific group of bioactive compounds called ketones.
Our hungry brains require vast amounts of energy, whilst accounting for just 2% of our body weight, they demand 23% of our energy expenditure. The majority of our fuel for the brain comes in the form of glucose, the byproduct of carbohydrate breakdown. There is however an alternative source of fuel for the brain, called ketones as discovered in the 1960’s by Dr George Cahill.
Ketones are produced as a result of breaking down of fat. When glucose is absent, the body turns to its own stored reserves of body fat to burn as a source of fuel, resulting in ketones. However, in order to access the stored fat for fuel, glucose levels must first be depleted. This is where the magic of fasting comes into play.
When we fast, the body first turns to the stored glucose within our liver, called glycogen, to use for fuel. There is approximately 900 calories worth of stored glycogen in the liver and takes about 14 hours of fasting to use up this stored source of glucose…after that the body turns to stored fat to seek out fuel to make the necessary energy.
When we burn fat for fuel, ketones are produced. These compounds are used in place of glucose to produce ATP, the body’s currency of energy. Ketones are a highly effective source of fuel, producing more energy pound for pound than glucose. Ketones produce less free-radicals during energy production within our cells, giving them their anti-aging status. Ketones also have anti-oxidant properties, donating electrons to unstable free-radicals.
Ketones circulate in the blood, passing though the blood-brain barrier to fuel the brain cells. This is of great benefit to those with insulin resistance, a condition that results from over consumption of sugar and results in a glucose deficit in the cells of the brain. Poor cognitive function, poor memory, poor focus and low mood can set in as a result of this inability of brain cells to use glucose for fuel. It is also of great benefit during perimenopause and menopause, when the fuel supply to the brain can become compromised with changing hormone levels.
Ketones have been shown to enhance cognitive function in individuals with insulin resistance and glucose deficit…essentially providing the brain cells with the fuel needed to function optimally.
It is the ability of ketones to cross the blood brain barrier and enter into the cell to create fuel that confers the many benefits on brain health and function.
Ketones have also been shown to reduce cravings and normalise appetite through their impact on hunger hormones, increase metabolic rate as well as improving various aspect of brain health such as increased cerebral blood flow and ease of energy production in the brain.
It is fasting that provides access into the highly beneficial world of ketones. In order to increase circulating ketone levels, we need to allow our body to access fat to burn for fuel. This can be from the fat on our plates, or the fat stored on our body. Ketone levels can also be increased by consuming foods rich in Medium Chain Triglycerides (MCT). This includes MCT oil, which can bump up your ketone levels, reduce cravings and increase energy and focus.
A Beginners Guide to Fasting…
1. Start slowly
You have essentially trained your hunger hormones to peak at meals times. Ghrelin, a powerful hunger hormone that drives appetite, will peak to match the times of day when you usually eat. If you eat very regularly, you will have peaks in ghrelin very regularly, therefore if you want to reduce the regularity of your hunger, reducing the regularity of eating will help to reduce the hunger hormone ghrelin. Ghrelin peaks can be shifted by about 45min per day, therefore if you usually have breakfast at 8am, begin by moving it to 8.45am, then 9.15am the next day and so on until you reach 12pm over a five day period.
2. Start with an overnight fast
Stopping eating at 7pm in the evening and breaking your fast with your first meal at 12pm creates a 17-hour fasting window. Working up to this over a few weeks provides a great goal. Overnight fasting can be done once or twice a week or more regularly.
3. Ensure you have plenty of water
We lose water when we reduce our insulin levels (as a result of fasting), which can have beneficial effects on our blood pressure and bloating. It is possible to lose electrolytes such as sodium, magnesium, potassium and calcium during a fast. These can be replenished through adding a little sea salt or Himalayan salt to water or using an electrolyte supplement.
4. Break you fast with low carb foods and protein
To help keep ketones circulating and encourage fat burning, reduce sugar intake and consume healthy fats such as coconut milk and coconut oil. Coconut is a rich source of a special group of fats called MCT, which is converted by the liver into ketones.
Intermittent fasting has been a way of life for our hunter gatherer ancestors and remains that way for many individuals globally, whether for religious or health benefits. The ability of the brain and other organs of the body to switch from glucose to ketones for fuel could hold the key to optimising our health.
Individuals who are diabetic or pre-diabetic, taking insulin or any other medication for diabetes or those prone to low blood sugars, should consult your doctor before deciding to fast.
To learn more about how to increase fat-burning and balance hormones, read Pauline Cox MSc latest book Hungry Woman - Eating for Good Health, Happiness + Hormones.
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