Time-Restricted Eating and Running Performance - She Runs Eats Performs

Episode 45

Published on:

25th Feb 2021

Time-Restricted Eating and Running Performance

TRE and running performance

Time-Restricted Eating (TRE) is well known for promoting general health and wellbeing, but have you ever considered introducing it to support your running performance? In this episode we delve into the science behind time-restricted eating before discussing the potential PROS and CONS of time-restricted eating for sports performance. We also outline some questions you should ask yourself to help you determine if it is the correct approach for you. 

Show Notes


Defining Time Restricted Eating before moving on to describe its connection to the body’s Circadian System, which organises metabolism, physiology and behaviour within a daily cycle of circadian rhythms. Outlining the potential benefits to general health and wellbeing including:

  • Insulin sensitivity
  • Glucose tolerance
  • Reduced risk of metabolic disorders including: diabetes, insulin resistance, cardiovascular disease.


“Eat like a king in the morning, a prince at noon, and a peasant at dinner”. Appreciating this quote and analysing how TRE could sit alongside this way of eating. 


Explaining how the circadian system works and outlining the various external factors that may influence its function. Factors including:

  • Light
  • Feeding - what we eat 
  • Physical activity and its timing
  • Sleep - quantity and quality 


Thinking about Circadian System synchronicity and how TRE may help maintain the synchronicity between the 2 parts of the system.


Looking at the potential PROS to running performance from introducing a TRE plan including:

  • Weight loss
  • Energy intake not restricted – beneficial for endurance runners
  • Transient hypoglycaemia – may be reduced 
  • Use of fat as fuel – preserving glycogen stores


Moving on to address the potential pitfalls of TRE for running performance including:

  • Loss of muscle mass
  • Poor food choices – energy dense, not nutrient dense
  • Poor endurance performance – in runs over 90mins
  • Stress response – potentially adding to the body’s stress burden



  1. Hormonal Imbalance: for female runners with any sex hormonal imbalance TRE may not be an ideal approach due to the potential stress response, which may further disrupt hormonal balance
  2. Pregnancy: Definitely not a recommended approach for any runners who are pregnant due to the additional energy/nutrient requirements of pregnancy. 
  3. Half/full/ultra marathon distance: Due to the intensity of training and long distances being run during training TRE wouldn’t be recommended due to the limitations of Fasted State Running, but also the limited ability to take on sufficient energy during the eating window.


Considering how to introduce Time Restricted Eating alongside your running training, but also highlighting the key questions to ask yourself before embarking on this approach to eating. The key questions include:

  • Within how many hours will your eating window be? 
  • At what time of the day will you start/end eating? 
  • How do your timing decisions fit in with your work/home/family situation? 
  • How do your timing decisions fit in with when you train? 
  • Will it support my training or hinder my running performance? 

 Moving on to think about how to introduce TRE into your plan; take it slowly, ensure optimal everyday nutrition is in place first, ensure your food choices are nutrient dense, maybe begin with 14:10 eating window and build up to 16:8.



1) TRE is only one form of Intermittent Fasting, however it is the one most studied when relating it to exercise and exercise performance.

2) TRE it is thought to be supportive to health and wellbeing principally because of its potential to maintain the synchronicity of the body’s circadian system

3) Remember, TRE may not be suitable for every runner. Factors need to be considered including:

  • Running distances
  • Current BS control
  • Current stress levels
  • ALSO, current health concerns

4) There are several potential benefits of TRE on running performance including:

  • Weight loss
  • Reduction in transient hypoglycaemia
  • No restrictions to energy intake, so could be suitable for some longer training

5) BUT there are some pitfalls to TRE that a runner would need to consider including:

  • Possible loss of lean muscle mass
  • Potential to over/under eat
  • Potential to make poor food choices
  • Stress response and the fallout from that including inflammation, increased risk of injury and illness. 

6) Ask yourself these questions before embarking on TRE:

  • Is this the correct approach for me?
  • Will it support my training or hinder my running performance?

Related Episodes:

Ep18 Intermittent Fasting and the Female Runner


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.

Aileen Smith and Karen Campbell met at as nutrition students (Institute for Optimum Nutrition, London) and became lifelong friends and nutritional buddies! Both have a love of running and a passion for nutrition, delicious food and healthy living.

Together they host RUNNERS HEALTH HUB. A place for like-minded runners who are looking for simple ways to support running performance, energy, endurance, and general great health.

We are excited to be able to share our expertise, experience and short cuts with you. We hope you'll join us again. If you'd like to know more about us and She Runs Eats Performs please check out our TRAILER.

If you're ready to make learn more about how you may introduce easy nutrition into your running and training plan join our Easy Nutrition For Healthy Runners Online Programme for short videos, recipes, downloads and LIVE training and Q&A.

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If you’d like help from Karen and Aileen to design a personalised sports nutrition plan for your running - please contact them at hello@runnershealthhub.com

Happy Running!

Aileen and Karen




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About the Podcast

She Runs Eats Performs
for mid-life female runners of all abilities
Are you confused about the science around nutrition for runners? Listen in to learn about the WHY, HOW, WHAT, and WHEN of eating to fuel your running performance.

We are here to help you translate sports nutritional science, into easy to apply tips and plans, helping you enjoy peak running performance. We focus on the FEMALE FACTORS every mid-life woman needs to know to be a healthy runner.

About your host

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Aileen Smith

Nutritionists, Educators, Podcasters, Runners and Friends

We have a love of running and a passion for nutrition, delicious food and healthy living. She Runs Eats Performs for female runners of all abilities who are looking for simple ways to improve their running performance and their health with nutrition and lifestyle.
We enjoy sharing our nutritional expertise, reviewing the latest sports science and most of all helping you to take easy action so you can enjoy your running life to the full.
We are here to help you achieve great health and good shape whilst staying injury-free with easy-to-understand sports nutritional concepts and easy-to-implement tips and plans.

Aileen and Karen are BANT and CNHC Registered Nutritional Therapists.