Ketogenic Diet and Exercise Performance

March 25, 2021

Ketogenic Diet and Exercise Performance

The Ketogenic diet is well known as an approach for weight loss, at least in the short term, and has been used as an adjunct treatment for epilepsy and other neurological conditions. BUT, is it an appropriate diet for endurance athletes?

In this episode we explore what the ketogenic diet is, and our current understanding of its use as an approach to health.

We consider its influence on exercise performance and translate all this information into recommendations for you as runners. We look at the questions:

  • What are the potential detrimental side effects for health and running performance?
  • What are the benefits to performance from using fat as fuel?
  • Could the Ketogenic diet be manipulated to support running performance?
  • Could it be suitable for some runners but not others?
  • Could it be suitable at certain times during a runner’s annual training cycle?

LISTEN HERE Episode 48: Ketogenic Diet and Exercise Performance


Ketogenic Diet and Exercise Performance


Defining the Ketogenic diet as low carbohydrate:high fat diet, where carbohydrate intake is reduced to as little as 10% of the overall daily macronutrient intake. Also, outlining some food ideas and quantities to consider if following this stye of eating.


Looking at energy production when following a Ketogenic diet, thinking specifically about:

  • Gluconeogenesis
  • Ketogenesis

A brief introduction to gluconeogenesis is given before focusing on Ketogenesis in more depth including an outline of some of the known general health benefits and possible detrimental effects of this dietary approach.


Moving on to consider how the Ketogenic diet may influence exercise performance. Thought is given to the benefits of using fat as fuel, but the demand for oxygen when shifting from carbohydrate to fat metabolism and the subsequent potential effects on performance are also debated.


Translating all the information and current research theories discussed into recommendations for runners of all abilities. Considering aspects including:

  • The potential for nutrient deficiencies
  • Running in the fasted state and its ability to support efficient utilisation of “fat as fuel”
  • Manipulating the ketogenic diet to support running training


Ketogenic Diet and Exercise Performance

  1. Regarding weight loss and blood sugar balance, the ketogenic diet has been found to have fewer positive effects in females compared to males.
  2. The influence of oestrogen may be a factor in WHY the Ketogenic diet is less effective in women besides men.
  3. The Ketogenic diet may be more suitable for post-menopausal women when oestrogen levels are naturally reduced.
  4. This diet is difficult to maintain in the long-term so may lead to rebound weight gain. Subsequent weight loss may be more difficult to achieve, especially for women in midlife.
  5. This diet could lead to the removal of a complete food group; a food group important for general health, but also many female specific aspects of health, including: sex hormone balance, blood sugar control and cortisol stability.
  6. More research is required into the ketogenic diet and its impact on female (and male) runners.


Ketogenic Diet and Exercise Performance

1) The Ketogenic Low Carb High Fat Diet is one where Carbohydrate intake is reduced to a minimal daily intake and replaced with a much higher intake of fat.

2) This diet appears to have a place in medicine as an adjunct treatment for certain medical conditions e.g. epilepsy

3) There is limited research into this diet and its effects on exercise performance, and the studies carried out todate do not appear to suggest it IMPROVES performance

4) Studies do suggest the ketogenic diet could increase peak aerobic CAPACITY

5) The ketogenic diet appears to have several side effects including an increased risk of

  • Dehydration
  • Electrolyte disturbances
  • Hypoglycaemia
  • Vitamin and mineral deficiencies

6) Also, it has been shown to be unsustainable in the long-term and when used as a weight loss strategy may result in rebound weight gain when removed.

7) We would not recommend this approach for running performance, we suggest a more balanced diet and using the different macronutrients strategically to manipulate their performance enhancing capabilities

Related Episodes:

Nutrition Periodisation for Runners

Macronutrients to Help Runners go Faster and Longer


The suggestions we make during this episode are for guidance and advice only, and are not a substitute for medical advice or treatment. If you have any concerns regarding your health, please contact your healthcare professional for advice as soon as possible.

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