Hey - I am Dr. James Morehen...
Firstly, I would like to say a big hello. I am excited to be part of the Kinetic Kitchen journey and it is a pleasure to be working alongside Harry and Mike.
Mike and I work together at Bristol Bears Rugby and I have seen first-hand his quality of work. Hand on heart, to date, he is the best Performance Chef I have worked with in my career. Most, if not all the rugby players and staff at Bristol Bears will also agree.
For my first blog, I want to address a hot topic in sports and nutrition circles. It is an area many athletes ask me about and an area I have enjoyed reading up on. So here goes…
Let’s get into it
Working in professional sports for over 9 years, I have been asked about many nutrition-related diets. To name a few, some questions put towards me have been:
- What do you think of time-restricted feeding?
- Will intermittent fasting help me with my performance?
- Can I consume too much protein in my diet?
- Should I follow a low-carbohydrate, high-fat diet?
- What do you think about the ketogenic diet?
Considering Kinetic Kitchen is a keto bakery (as well as gluten-free, organic etc) and one of their best-selling products is the KETOnuts (by the way, I have tried them, and WOW!), I wanted to share some information on what the ketogenic diet is. Amazingly, “keto” was the top trending diet on Google in 2018.
First and foremost, we need to define what ketogenic is. In the textbook The Ketogenic Bible: The authoritative guide to Ketosis there are 6 definitions of a ketogenic diet. One thing they all have in common is significantly reduced carbohydrates:
- Less than 50g of carbohydrates per day (or 5% to 10% of total daily caloric intake) and dietary fat as high as 90% of total daily caloric intake (Paoli et al., 2013).
- Less than 50 grams of carbohydrate per day regardless of fat, protein or caloric intake (Westman et al., 2003).
- Four times as much fat as carbohydrates, with protein regulated so that 90% of calories are derived from fat (Swink et al., 1977).
- Less than 50 grams of carbohydrate per day or approximately 10% of total daily calories from carbohydrates (i.e., 200 calories on a 2000 calorie-per-day diet) (Accurso et al., 2008).
- High fat, low protein, and low carbohydrate (Freeman, 1998).
- An ad libitum (“free-feeding”) diet consisting of less than 50 grams of carbohydrates per day (Gregory et al., 2017)
I like the definition of:
“A ketogenic diet consists of high fat, adequate protein, and low carbohydrate intake (normally less than 50g of total daily carbohydrate intake)”.
Although we have defined a ketogenic diet, it is important to not confuse it with a low carbohydrate product or actual physiological ketosis within the body.
From my research online (February 2023), I cannot find any universal or agreed definition of what constitutes a “keto” product or food type. For individuals to follow a ketogenic diet, it makes sense for daily nutritional intake to be made up of food types which contain a low carbohydrate content (of which Kinetic Kitchen have many), but for an actual product to be “keto”, I'm afraid right now there is no available definition in a scientific published journal. Additionally, it is important to note that the consumption of a single food will not result in physiological ketosis.
Having said this, many will agree that to kick-start and generate increased ketone concentrations within the body, individuals need to remain on a low-carbohydrate diet for several days (normally 2-4 days) depending on the individual factors (i.e., age, fitness levels, metabolism). Therefore, any products being consumed by someone wanting to start or maintain a ketogenic diet needs to be low in carbohydrate.
For this blog, we shall define a keto product as one that contains a low amount of carbohydrates per 100g for example less than 5g carbohydrate per 100g.
At this point, it is important to understand there are many other examples of food and drinks which contain low carbohydrates (per 100g) including:
- Whey protein
- Spinach, cucumbers, peppers, and other vegetables
- Some protein bars
- Some protein yoghurts
- Some protein ice-creams
- And of course, the KETOnuts, Brioche Loaf and Cinnamon KETOrolls
So how does ketosis happen
Either way, very low intakes of carbohydrates (normally <50g) lead to physiological ketosis in the body. In this process (and we won’t go too sciency, but it’s important to know a little) ketone bodies are released from the liver from the breakdown of fats and converted to acetyl-CoA, which enters the Krebs cycle and are oxidised for energy.
Ketone bodies are water-soluble organic compounds derived from lipids (fats). They have gained wide interest due to the possibility of providing an alternative fuel source for the brain (therefore you may have heard some people say they have more clarity around focus and attention), heart, and skeletal muscle. Ketone bodies are increased by low carbohydrate availability, due to fasting (i.e., not consuming food for a period during the day or overnight when you sleep) or following a ketogenic diet.
Nutritional ketosis is the process of intentionally restricting dietary carbohydrates to accelerate ketone production to induce a metabolic effect that stabilises blood sugar and minimises insulin release. It is nutritional ketosis that most people try to do, rather than achieve ketosis from external supplements.
You can use supplements to achieve ketosis. Exogenous ketone supplements (EKS) are a collective term for ketone salts, ketone precursors, and ketone esters aimed to achieve nutritional ketosis. This effect can influence metabolism both at rest, during, and after exercise within minutes of ingestion and be maintained for several hours depending on the type and dose of EKS. These effects have led to considerable interest in EKS as beneficial agents in athletic performance, recovery, and beyond.
In 2016, the first research on this topic was published, and interest has increased regarding the effects of acute ingestion of EKS on exercise metabolism, physical and cognitive performance, and post-exercise recovery. This paper assesses the mechanisms associated with the increase in ketone bodies that could potentially enhance or impair performance. It also analyses the effect of EKS on exercise performance and recovery.
Measuring Circulating Ketone Bodies Concentrations
It's essential to measure the circulating ketone body amounts to determine the metabolic changes associated with acute nutritional ketosis. Without measuring, individuals will have no idea if they are actually in ketosis or not. An individual on a regular diet will typically have ≤0.1 mM of blood ketone bodies after a meal and ~0.1 to ~0.4 mM after an overnight fast. Whereas nutritional ketosis is defined as having ≥0.5 and 3 mM of blood ketone bodies.
The common way to measure this concentration is a handheld point-of-care (POC) device. These were originally used to handle and monitor ketoacidosis in clinical patients but are now popular for monitoring adherence to a ketogenic diet. These devices use strips that contain enzymes to give users rapid feedback on their blood ketone body concentration. Some factors can influence ketone body concentration, which should be considered before measuring. For example, capillary samples often overestimate readings compared to serum samples and hematocrit value (amount of red blood cells in the blood) or pH of the blood can increase ketone body concentrations.
Mechanisms of Exogenous Ketone Supplements to Potentially Benefit Performance
There are three metabolic effects of short-term nutritional ketosis that could potentially act as ergogenic aids for exercise performance: 1) oxidation of ketone bodies as an alternative energy substrate, 2) efficiency of ATP production when ketone bodies are used as a substrate, 3) reduced reliance of carbohydrate utilisation during exercise.
Oxidation of Ketone bodies as an Alternative Substrate
Substrate utilisation during exercise is predominately carbohydrate and fat and negligible contributions from other substrates including amino acids, ketone bodies, and lactate. Two studies have suggested that the average contribution of the ketone body to energy provision when an athlete is in nutritional ketosis (~1.7 to ~4.5 mM) after consuming EKS is ~2.5 to ~4.5%, and ~7.4 to ~8.4%. These results exist despite the difficulty of accurately measuring ketone body concentrations in the body.
This is not unexpected as further in vitro research suggests that ketone bodies have a small effect on mitochondrial respiration, particularly when other sources (e.g. pyruvate) are available. Furthermore, higher oxidation rates have been observed at higher exercise intensities, despite the greater reliance on carbohydrates as a utilised substrate (75% vs 40% VO2max). Interestingly, endurance-trained athletes are believed to be better adapted to utilise ketone bodies, as their skeletal muscle has higher uptake rates, increased activity of ketolytic enzymes, and greater oxidation rates.
The efficiency of ATP Production When Ketone bodies are Used as a Substrate
Despite ketone bodies' seemingly insignificant role in supplying energy during exercise, a critical question is whether they are a more efficient source of ATP (energy) production. Ketone bodies have a higher energy yield per carbon unit compared to glucose and/or pyruvate, but long-chain fatty acids have higher values for energy per ATP than ketone bodies. However, ketone bodies are more efficient than fatty acids at the amount of ATP produced per oxygen molecule, though glucose is the most efficient among the three substrates.
A regularly referenced illustration of improved energetic efficacy associated with ketone bodies as a substrate comes from a working rat heart model, where acute ketosis can raise the contribution of ketone bodies to energy provision and amplify cardiac output and myocardial oxygen consumption. This effect in the skeletal muscle would be seen as greater power output for the same amount of oxygen utilisation, or vice versa, during an exercise conducted in acute nutritional ketosis.
When testing this effect on performance, there are conflicting results as to whether ketone bodies reduce the oxygen cost of steady-state exercise (50-75% VO2 max). Because of limited high-quality research and bias towards no distinctions in steady-state oxygen uptake or exercise efficiency, more research needs to determine if raised ketone body concentrations elicit this performance benefit.
Ketone bodies Reduce Reliance on Carbohydrate Utilisation During Exercise
Contributions from substrates in skeletal muscle during exercise is a complex interaction between exercise intensity, extra- and intramuscular substrate availability, and training status. Acute nutritional ketosis has been observed to increase the contribution of fat to energy provision (predominately in the form of intramuscular triglyceride) during moderate-intensity exercise. This could reduce the reliance on carbohydrate oxidation, termed ‘glycogen sparing’. Sports that are limited by glycogen stores may benefit from nutrition strategies that ‘spare’ glycogen utilisation, such as team and endurance sports. However, ketone bodies are proposed to inhibit key enzymes that inhibit glycolysis and increase the conversation of glucose in glycogen. This questions whether nutritional ketosis ‘spares’ carbohydrate or ‘impairs’ carbohydrate utilisation.
The ketogenic diet has been considered a possible alternative to extreme caloric restriction to tackle increases in body fat by athletes in the off-season. However, research on the ketogenic diet is conflicting. Certain studies report negative effects on performance following the ketogenic diet, whilst others suggest a positive effect, or no difference compared to ‘western’ diets.
Adherence plays a central role in the success of athletes following a ketogenic diet. I would question whether eliminating or heavily restricting carbohydrates from the diet is necessary since safe body composition manipulation can be achieved through a nutritional intake that periodises energy intake aligned with the training demands of each day. There are times when you will need carbohydrates in your diet to have the energy for training and exercise, but there are also times when you do not need a big carbohydrate intake due to a lack of energy expenditure or training. This is where Kinetic Kitchen is a perfect option. I for one have been consuming Kinetic Kitchen low-carbohydrate breads with my eggs in the morning instead of traditional slices of bread.
If I or my athletes that I work with fancy a sweet treat but want to keep it low in carbohydrates then the KETOnuts are a nice option with a cup of tea in the evening.
In summary, I hope this blog has provided you with an understanding of what ketosis is and how it works. Remember that nutritional intake is a key part of human life and there are times when carbohydrates are going to be important for energy (i.e. to increase glycogen availability in your muscles to fuel you running a marathon) but also when carbohydrates do not need to be consumed in high volumes.
In the next blog, I would like to cover two key areas of nutrition right now which are fuelling for the work required (i.e. how to fuel training and exercise) and eating with intent (i.e. how to consume the right foods, in the right amounts and at the right times of the day).
Any questions please pop them in the comments section below.