Lots of people talk about the benefits of the ketogenic diet, but what does the research say? Here is some of the science on how going keto may enhance your health, fitness and lifestyle.
Metabolic flexibility is the capacity for the body to effectively utilise both carbohydrates and fats for fuels. Being healthy is associated with full metabolic flexibility whereas being overweight and type 2 diabetes is associated with metabolic inflexibility (1).
Lifestyle, diet and exercise, as well as life events, such as pregnancies and medications influence your degree of metabolic flexibility. Usually, metabolic inflexibility refers to being less insulin sensitive and having a reduced capacity to break down fats (1,2).
Whilst someone who is metabolically flexible can respond to a meal higher in fat by upregulating the genes needed to help the process of it being broken down, someone who is metabolically inflexible may have reduced capacity to do this (3) and this may contribute to a greater propensity for weight gain (4).
The ketogenic diet is an effective tool to shift the spectrum of metabolic inflexibility. As the body adapts to nutritional ketosis it has to reduce insulin levels and build the metabolic machinery to effectively break down fat and generate ketone bodies. The ketogenic diet may increase the expression of the genes required for fat metabolism (5) and induce changes to the mitochondria (power house of the cell) (6) which may enhance fat oxidation.
Ketone bodies may affect the expression of other genes, a term described as epigenetic (7) which may also contribute to metabolic adaptations.
Note: be mindful of sticking to the ketogenic diet long term and this affecting your capacity to be metabolically flexible with carbs!
Improved insulin sensitivity
Reduced insulin sensitivity and insulin resistance is associated with conditions such as: type 2 diabetes, cardiovascular disease and polycystic ovarian syndrome (PCOS) (8). Insulin is an important hormone with diverse roles, such as: regulating glucose uptake into muscle and fat cells, regulating fat storage, synthesis and breakdown, and assisting in the relaxation of blood vessels and arteries.
Remaining insulin sensitive facilitates the insulin signalling processes functioning effectively and cells responding appropriately. Being insulin sensitive is associated with remaining lean and metabolic flexibility (1,9).
To get into nutritional ketosis, insulin levels must be low enough for fat to be broken down and ketone bodies to be generated. Therefore the ketogenic diet significantly reduces insulin levels (10,11,12) and may increase insulin sensitivity in individuals with type 2 diabetes (12).
Going keto is also associated with weight loss which improves insulin sensitivity (10). The epigenetic properties of ketone bodies may also contribute to increased insulin sensitivity (7).
Note: there is only research on individuals with type 2 diabetes to indicate improved insulin sensitivity.
Improved blood sugar levels
Consistently elevated blood sugar levels and/or spikes in blood sugar spikes can be damaging to health. They are associated with formation of harmful substances, such as advanced glycation end (AGE) products, over production of reactive oxygen species (ROS) and a pro inflammatory response (13). These are all then associated with the development of chronic diseases such as type 2 diabetes (13).
High blood sugar levels also subsequently increase insulin levels and are therefore associated with those corresponding health conditions, such as cardiovascular disease, type 2 diabetes, PCOS (8).
Studies on type 2 diabetes, show that the ketogenic diet reduces markers of blood sugar levels (HbA1c) (12,14,15,16). Type 2 diabetes, characterised by high blood sugar and insulin levels, is also shown to be improved and reversed by the ketogenic diet (12,14,15,16).
The ketogenic diet demands carbohydrate intake to be substantially reduced. Since carbohydrates are broken down into sugars, reducing carbohydrate intake subsequently reduces blood sugar levels.
Note: there are many other factors that affect blood sugar levels and two different carbohydrates can have very different impacts on blood sugar levels depending on their protein and fibre content.
Better body composition
Going keto is associated with improved body composition, usually referred to as fat loss and either maintained or increased muscle mass (17,18,19,20,21).
Adapting to nutritional ketosis requires insulin levels to be lowered and the upregulation of the metabolic machinery to breakdown fat. Low levels of insulin signal to the body that fat can be broken down and upregulates genes that breakdown fat.
Muscle mass retention/increase may partly be due to increased protein intake which is almost doubled in most of these studies (17,18,19,20,21). Protein stimulates the muscle protein synthesis pathway by activating a protein called mTOR (mammalian target of rapamycin) (22,23). Ketone bodies themselves may also induce protein synthesis (24), as well as protecting against the breakdown of muscle (25).
Additionally, many studies incorporated resistance training, (18,19,20,21) which provides the necessary stimulus to activate muscle protein synthesis (23).
Note: studies do seem to indicate that the ketogenic diet results in superior body composition results! The type of ketogenic diet and protein intake, as well as training will inevitably influence these outcomes.
Improved inflammatory levels
Maintaining an optimal balance of inflammation is critical for good health. Most chronic diseases are associated with continual low level inflammation. Clinical studies indicate that a ketogenic diet reduces levels of inflammatory biomarkers significantly more than comparative diets (26).
The ketone body β-hydroxybutyrate (BHB) may inhibit a series of pro inflammatory reactions, subsequently reducing levels of inflammatory biomarkers (27).
Note: there isn’t the research to conclude that a ketogenic diet would impact systemic (whole body) inflammation yet.
Increased antioxidant defence system
Overproduction of reactive oxygen species (ROS) is associated with an inflammatory response, the development of chronic health conditions and aging. The anti-oxidant defence system is important in maintaining balance against the production of ROS.
The ketone body BHB has been shown to both decrease the production of ROS (28) and increase antioxidant defences (29). The epigenetic properties of BHB may upregulate the expression of certain anti-oxidants, for example glutathione (30).
Note: current research is experimental only.
For more details, check out Does going keto benefit the athlete? To summarise, research is mixed as to whether the ketogenic diet benefits performance outcomes. Some benefits for the keto-adapted endurance athlete may include: avoiding the hitting the wall phenomenon, reduced gastrointestinal distress and delayed central fatigue.
For power/strength training, research is more questionable due to the requirement for the glycolytic system which utilises carbohydrate as a substrate.
Going keto is also indicated to enhance the recovery process and improve symptoms of muscle soreness due to the anti-inflammatory properties of ketone bodies (27).
Note: there is only the research to show that going keto increases capacity to utilise fat for fuel.
Better brain health
The ketogenic diet is a proven therapy for epilepsy (31) and ketone bodies may be neuroprotective and benefit neurodegenerative disease. Ketone bodies may be a more metabolically efficient fuel source for the brain than glucose (32), beneficial for states of cognitive decline and neurodegenerative diseases when the brain receives inadequate energy and subsequently brain cells (neurons) become dysfunctional and dye.
Ketone bodies may also enhance cognition and alertness via their impact on the mitochondria (6), and also have a calming effect due to influencing the ratio of excitatory to inhibitory neurotransmitters (glutamate to GABA) (33).
Since ketone bodies may be anti-inflammatory (27) and up regulate the anti-oxidant defence system (30), this may also improve the aging process and protect against neurodegeneration, both of which are associated with the overproduction of ROS and inflammation.
Note: there is no research on healthy individuals to show the impact of the ketogenic diet on brain health.
Final words for now…..
The research to support the health benefits of going keto is mostly conducted on people who already have health conditions, for example type 2 diabetes or very overweight. We cannot assume that these benefits apply to someone who is already relatively healthy / lean.
Should I go keto as an athlete dives into the potential benefits for individuals who train in more detail and definitely check out What are the downsides of going keto to get the other side of going keto.
10 tips to starting a ketogenic the right way can also help you to begin you keto journey successfully!
Let me know your thoughts below – have you gone keto and experienced any of these benefits? Have I left anything out that works for you?
Thank you for reading!