What is Ketosis?
Ordinarily, human bodies run on a mixture of carbohydrate and fats.
Each meal we consume props up our blood sugar level and we primarily run on carbohydrates and when our blood glucose levels begin to drop, we would normally eat our next meal.
And while we sleep at night, our bodies start to shift to a higher amount of fat for metabolism and for the physical repair that occurs during our sleep cycles but glucose is still primarily used to support our active brains during dreaming.
However, if we consume a diet that removes a considerable portion of carbohydrates and replaces them with fat, within 24 or so hours, our liver and muscles become depleted of their carbohydrate stores and our body mobilizes body fat, transports it to the liver and the liver produces an ‘alternative fuel source’ known as ketone bodies.
Ketone bodies, which are technically water-solublechemical substances, are comprised of acetoacetate, beta-hydroxybutyrate and acetone.
Once released by the liver, ketones enter into the blood stream and all cells with mitochondria can take ketone bodies up from the blood and reconvert them into acetyl-CoA, which can then be used as fuel in their citric acid cycles.
Unlike free fatty acids, ketone bodies can cross the blood-brain barrierand are therefore available as fuel for the cells of the central nervous system, acting as a substitute for glucose, on which these cells normally survive.
Is diet the only way we can get into ketosis?
Elevated levels of ketones in the blood can occur via several methods, namely during starvation, fasting, prolonged heavy endurance exercise, consuming supplemental ketone salts or esters or by eating a low carbohydrate, high fat ketogenic diet.
How quickly do we switch from glucose burning to fat-metabolism?
The answer varies from person to person, as there are considerable individual differences in the degree of metabolic flexibility that allow it to switch metabolic substrates effortlessly.
Most studies show that the transition from glucose metabolism to ketosis, where beta-hydroxybutyrate levels are consistently over 0.7 mmol/l, occurs within around 5 days.
But what about performance?
Leading expert in the field, professor Dominic D’Agostino, has suggested that the length of time it takes for the metabolic machinery (enzymes, transporters, mitochondria etc...) to adapt to ketone metabolism might be anywhere from 2 weeks to 8 months, with the average being 3–6 months.
This means one would experience a short-term decrement in their physical performance until the metabolism had fully adjusted to the alternative fuel source..
Research has generally shown that once adapted to the ketogenic diet, both strength performance, body composition and endurance performance does not seem to be impaired.
However, a recent study by professor Louise Burke and colleagues found that a 3-week ketogenic diet in elite level race walkers reduced inflammation.
Is a ketogenic diet good for me?
Ketogenic diets are not suitable for everyone.
20% of the population might have issues handling such a high-fat diet.
Likely reasons might be genetic or possibly related to the microbiome.
There are also a variety of fatty acid oxidation disorders.
It would be advised to have several blood tests within a few months of transitioning to the diet to assess lipid status to ensure no adverse responses to the high fat content.
Individuals who tolerate carbohydrate rich diets well (hunger is controlled, few post-meal dips in energy, no blood sugar crashes) would most likely find little benefit from swapping to a ketogenic diet, as they are already insulin sensitive.
Conversely, it is now well accepted that those with type II diabetes and insulin resistance, which is typified by carbohydrate intolerance, would most benefit from adopting a low carbohydrate, high fat diet.
Will a ketogenic diet make me lose body fat?
Many people are attracted to the ketogenic diet because of the surface claim that you will increase ‘fat burning’.
Despite the clear metabolic shift from glucose metabolism to fat during ketosis, research has clearly demonstrated that the primary driver of weight loss is a negative energy balance over time and not the diet type.
This was recently shown in two very well controlled studies lead by Dr. Kevin Hall at the NIH. Dr. Hall did note that most subjects on the ketogenic diet reported less hunger and had difficulty eating all the food amounts they needed to for the study and all subject’s insulin levels were reduced by 50%.
This has enormous implications for those who have difficulty controlling their appetite, overeating and those with elevated insulin levels.
What are the best keto foods?
- Seafood - fatty fish like salmon, mackerel, sardines etc are the best
- Grass-fed, free range meat and poultry (pork belly a favourite for us!)
- Slow cooked bone broths
- High quality whey protein powder (e.g. Aus Natural Protein!)
- Vegetables - fresh, pickled and fermented
- Coconut and olive oil
- Full fat Greek yoghurt
- Nuts and seeds
- Butter and Cream
- Dark chocolate and/or cocoa powder
- Black coffee (With MCT oil) and tea (without milk)
Renowned sports scientist Dr Tony Boutagy, has a PhD in exercise and sports science from Charles Darwin University in Australia and is an Exercise Physiologist. Having conducted over 50,000 training sessions in his career that has spanned 25 years, Tony is regarded as one of the premier personal trainers in the country.