So periods of lower carbohydrate intake, which we might consider as a proxy although not a perfect one for intermittent fasting, may enhance or reduce training adaptations, depending on your overall training goal. Similarly, not eating before a high-intensity exercise, such as sprints and resistance training, also will likely reduce training performance and, in turn, hamper competition performance.

The only downside is when it comes to protein intake. While by far and away the most important factor with protein is total daily intake, some evidence suggests that eating g every hours provides a small advantage regarding muscle protein synthesis, which could affect muscle recovery and growth.

And though the impact of this may be small, it could make all the difference for elite athletes. Some evidence suggests that regular intakes of protein spaced throughout the day are better than larger intakes consumed less often. While the impact might be small, it could make the difference for elite athletes, and intermittent fasting would preclude this.

Given that high-level athletes require much more nutrition than non-elite athletes and must spread out these nutrients across the day when they have multiple daily sessions, this time-restricted approach seems to be a sub-optimal option. However for recreational athletes who train for shorter durations and with less intensity—and therefore have lower energy demands—intermittent fasting may be appropriate, especially for weight management.

More people are reading SimpliFaster than ever, and each week we bring you compelling content from coaches, sport scientists, and physiotherapists who are devoted to building better athletes. Please take a moment to share the articles on social media, engage the authors with questions and comments below, and link to articles when appropriate if you have a blog or participate on forums of related topics.

Since retiring, Craig has been working as Head of Sports Science at DNAFit, along with a number of other consultancy roles, including sports coaching. However, if I have not consumed enough calories the previous day I will likely struggle until I am burning ketones as my primary fuel — but it can take a while before this kicks in.

So long as my calorie intake is sufficient, all is well. My mind is clear, I feel light and sharp, both physically and mentally. ironically this is the case today! I have found intermittent fasting very useful but must be mindful to replace energy once it is burnt.

Which, as you said, can be difficult, especially if you need significant calories. Craig, thank you for this outstanding article. With all the new scientific information regarding the benefits of intermittent fasting it can become confusing for athletes who are training and need optimal fuel and energy for sustained performance.

Your article explains well the nuances of the fasting practice as well as the need for athletes in training to resume their fuel and high protein intake throughout the day. This article gives me the confidence to resume my training and fuel regime to obtain peak performance especially when training for a rigorous endurance event carrying heavy weight.

Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. Please contact the developer of this form processor to improve this message.

Active students reported decreased power and anaerobic capacity after ten days of intermittent fasting as assessed by the Wingate stationary bike test, although the study reported that power increased in the same group after four weeks.

Men and women who followed a strength training program had similar gains in muscle mass and strength when practising intermittent fasting compared to a control diet. There was no significant difference in muscle power between active men who did or did not practise intermittent fasting.

However, one study reported an increase in strength and muscular endurance in active young adults after eight weeks of strength training combined with intermittent fasting. So, as we see, the results vary greatly from one study to another and are influenced by several factors, including the type of fasting and its duration, the level of the athletes, the type of sport they practise and so on.

In addition, very few studies have been carried out in women. Also, the lack of a control group in most studies means the effect of intermittent fasting cannot be isolated.

So for the moment, it is not possible to draw a conclusion about the effectiveness of intermittent fasting on athletic performance.

Athletes who wish to use intermittent fasting should consider several practical issues before starting. Are their training schedules compatible with this dietary approach?

For example, does the period during which an athlete is allowed to eat allow them to consume enough food prior to doing physical exercise, or to be able to recover after the training? And, importantly, what about food quality, given that athletes must consume sufficient protein to recover and maintain their lean body mass and limit negative impacts on their performance?

Intermittent fasting may result in an energy deficiency that is too great for athletes with high energy needs to overcome. This could be the case for endurance athletes running, cycling, cross-country skiing, triathlon, etc.

due to their high volume of training. These athletes may end up suffering from Relative energy deficiency in sport RED-S , a syndrome that affects hormone secretion, immunity, sleep and protein synthesis, among other things. It is also important to question the motivation for adopting a dietary practice as strict as intermittent fasting.

Some people do it for religious reasons such as Ramadan. A recent study showed a significant association between intermittent fasting in the past 12 months and eating disorder behaviours overeating, compulsive exercise, vomiting and laxative use.

Although this study does not determine whether fasting causes eating disorders, or eating disorders lead to fasting, it does highlight an associated risk in this practice. Finally, the potential impact of intermittent fasting on social interactions must also be considered.

When implemented carefully, intermittent fasting can complement a runner's lifestyle and performance without compromising overall health. Disclaimer: The text, images, videos, and other media on this page are provided for informational purposes only and are not intended to treat, diagnose or replace personalized medical care.

Intermittent fasting has broad benefits for many health conditions, including obesity, diabetes, heart disease, certain cancers, and neurologic disorders [ 2. Research shows IF can improve metabolic health and blood sugar control by reducing insulin resistance, blood glucose, and fasting insulin levels [3, 5].

You can maintain your current running performance with IF as long as you prioritize your nutrition intake, training, and sleep [9].

Elo Smart Protein. International Food Information Council. de Cabo, R. Effects of Intermittent Fasting on Health, Aging, and Disease. The New England journal of medicine, 26 , — Longo, V. Fasting: molecular mechanisms and clinical applications.

Cell metabolism, 19 2 , — Mattson, M. Impact of intermittent fasting on health and disease processes. Ageing research reviews, 39, 46— Barnosky AR, Hoddy KK, Unterman TG, Varady KA. Intermittent fasting vs daily calorie restriction for type 2 diabetes prevention: a review of human findings.

Transl Res. doi: Epub Jun PMID: Heilbronn, L. Glucose tolerance and skeletal muscle gene expression in response to alternate day fasting. Obesity research , 13 3 , — Moro, T. Time-restricted eating effects on performance, immune function, and body composition in elite cyclists: a randomized controlled trial.

Journal of the International Society of Sports Nutrition, 17 1 , Brady, A. Effects of 8 wk of Time-restricted Eating in Male Middle- and Long-Distance Runners. Medicine and science in sports and exercise , 53 3 , — Chaouachi, A. The effects of Ramadan intermittent fasting on athletic performance: recommendations for the maintenance of physical fitness.

Journal of sports sciences , 30 Suppl 1 , S53—S Zouhal, H. Exercise Training and Fasting: Current Insights. Open access journal of sports medicine, 11, 1— Tinsley, G. Time-restricted feeding plus resistance training in active females: a randomized trial. The American journal of clinical nutrition , 3 , — Time-restricted feeding in young men performing resistance training: A randomized controlled trial.

European journal of sport science , 17 2 , — Home Articles The ultimate guide to intermittent fasting and running The ultimate guide to intermittent fasting and running Intermittent fasting has become one of the latest buzzwords in the health and wellness space. But why are people talking about it, and is there a way to safely fast, especially for runners?

Contents What is intermittent fasting? Named the most popular diet of in a study by the International Food Information Council, intermittent fasting IF has become a favorite way for many to manage their weight and improve their health [ 1 ]. What is intermittent fasting?

Types of intermittent fasting All variations of intermittent fasting split either the day or week into eating and fasting periods. Key takeaways Intermittent fasting has broad benefits for many health conditions, including obesity, diabetes, heart disease, certain cancers, and neurologic disorders [ 2 ].

Pre-workout and post-workout nutrition should be optimized to support exercise performance and recovery. Elo Smart Protein can be a convenient and cost-efficient way to boost protein and carbohydrate intake after a run to deliver the right amount of nutrients to optimize your recovery.

References International Food Information Council. pdf de Cabo, R. S Tinsley, G. Show more.

Trained cyclists reported increased fatigue and muscle soreness during Ramadan, but this may be partly due to dehydration, since fluids are also restricted during this period when you cannot consume anything from sunrise to sunset.

In the context of fasting, low glycogen carbohydrate reserves may limit the execution of repeated, intense efforts. Active adults reported a decreased speed in repeated sprints after fasting 14 hours per day for three consecutive days.

Active students reported decreased power and anaerobic capacity after ten days of intermittent fasting as assessed by the Wingate stationary bike test, although the study reported that power increased in the same group after four weeks. Men and women who followed a strength training program had similar gains in muscle mass and strength when practicing intermittent fasting compared to a control diet.

There was no significant difference in muscle power between active men who did or did not practise intermittent fasting.

However, one study reported an increase in strength and muscular endurance in active young adults after eight weeks of strength training combined with intermittent fasting.

So, as we see, the results vary greatly from one study to another and are influenced by several factors, including the type of fasting and its duration, the level of the athletes, the type of sport they practice and so on.

In addition, very few studies have been carried out in women. Also, the lack of a control group in most studies means the effect of intermittent fasting cannot be isolated. So for the moment, it is not possible to draw a conclusion about the effectiveness of intermittent fasting on athletic performance.

Athletes who wish to use intermittent fasting should consider several practical issues before starting. Are their training schedules compatible with this dietary approach? For example, does the period during which an athlete is allowed to eat allow them to consume enough food prior to doing physical exercise or to be able to recover after the training?

And, importantly, what about food quality, given that athletes must consume sufficient protein to recover and maintain their lean body mass and limit negative impacts on their performance?

Intermittent fasting may result in an energy deficiency that is too great for athletes with high energy needs to overcome. This could be the case for endurance athletes running, cycling, cross-country skiing, triathlon, etc. due to their high volume of training. These athletes may end up suffering from Relative energy deficiency in sport RED-S , a syndrome that affects hormone secretion, immunity, sleep and protein synthesis, among other things.

If the deficit is prolonged, this will have an adverse effect on an athlete's performance. It is also important to question the motivation for adopting a dietary practice as strict as intermittent fasting.

Some people do it for religious reasons such as Ramadan. Others are motivated by weight control goals and the hope of achieving an "ideal" body according to socio-cultural norms. A recent study showed a significant association between intermittent fasting in the past 12 months and eating disorder behaviors overeating, compulsive exercise, vomiting and laxative use.

Although this study does not determine whether fasting causes eating disorders or eating disorders lead to fasting, it does highlight an associated risk in this practice. Finally, the potential impact of intermittent fasting on social interactions must also be considered.

A fasting schedule may limit participation in social activities that involve food. What is the risk of negatively influencing the eating behaviors of other family members, especially children or teenagers who see their parents abstain from eating and skip meals?

With such conflicting scientific data, it is not possible at this time to come to a conclusion about the effects of intermittent fasting on sports performance. Further studies are needed before this practice can be recommended, especially for seasoned athletes.

Furthermore, the potential negative effects on other aspects of health, including eating habits and social interactions, are not negligible. A more recent review concluded that, as long as athletes maintain their total intake of calories and micronutrients and their typical sleep quality, they likely would not see any negative effects on performance.

For most people most of the time, the timing of these factors is less important provided they consume enough food and fluid. In fact, more recent research suggests that, for some athletes, periods of time with less—or even no—energy intake may help enhance performance.

An important training adaptation for endurance athletes is the production of new mitochondria, called mitochondrial biogenesis. When endurance athletes train, their bodies detect when energy stores are getting low, which releases several signaling factors including AMPK.

These signaling factors, in turn, stimulate many of the positive adaptations to endurance exercise, including mitochondrial biogenesis. As such, training in a low energy state is associated with enhanced training adaptations in some specific measures. So periods of lower carbohydrate intake, which we might consider as a proxy although not a perfect one for intermittent fasting, may enhance or reduce training adaptations, depending on your overall training goal.

Similarly, not eating before a high-intensity exercise, such as sprints and resistance training, also will likely reduce training performance and, in turn, hamper competition performance. The only downside is when it comes to protein intake.

While by far and away the most important factor with protein is total daily intake, some evidence suggests that eating g every hours provides a small advantage regarding muscle protein synthesis, which could affect muscle recovery and growth. And though the impact of this may be small, it could make all the difference for elite athletes.

Some evidence suggests that regular intakes of protein spaced throughout the day are better than larger intakes consumed less often. While the impact might be small, it could make the difference for elite athletes, and intermittent fasting would preclude this.

Given that high-level athletes require much more nutrition than non-elite athletes and must spread out these nutrients across the day when they have multiple daily sessions, this time-restricted approach seems to be a sub-optimal option. However for recreational athletes who train for shorter durations and with less intensity—and therefore have lower energy demands—intermittent fasting may be appropriate, especially for weight management.

More people are reading SimpliFaster than ever, and each week we bring you compelling content from coaches, sport scientists, and physiotherapists who are devoted to building better athletes. Please take a moment to share the articles on social media, engage the authors with questions and comments below, and link to articles when appropriate if you have a blog or participate on forums of related topics.

Since retiring, Craig has been working as Head of Sports Science at DNAFit, along with a number of other consultancy roles, including sports coaching.

However, if I have not consumed enough calories the previous day I will likely struggle until I am burning ketones as my primary fuel — but it can take a while before this kicks in.

So long as my calorie intake is sufficient, all is well. My mind is clear, I feel light and sharp, both physically and mentally. ironically this is the case today! I have found intermittent fasting very useful but must be mindful to replace energy once it is burnt. Which, as you said, can be difficult, especially if you need significant calories.

Craig, thank you for this outstanding article. With all the new scientific information regarding the benefits of intermittent fasting it can become confusing for athletes who are training and need optimal fuel and energy for sustained performance.

Your article explains well the nuances of the fasting practice as well as the need for athletes in training to resume their fuel and high protein intake throughout the day. This article gives me the confidence to resume my training and fuel regime to obtain peak performance especially when training for a rigorous endurance event carrying heavy weight.

Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. Please contact the developer of this form processor to improve this message. Even though the server responded OK, it is possible the submission was not processed. Fasting has garnered interest since research in animals has shown that those consuming fewer calories tended to live longer, says craigm Click To Tweet The research on intermittent fasting is somewhat scarce, with intervention studies both low in number and participants.

Insights from Athletes Observing Ramadan Of course, athletes are always looking for the next edge they can gain over their competitors, and intermittent fasting potentially represents such an edge.

Intermittent Fasting and Adaptation In fact, more recent research suggests that, for some athletes, periods of time with less—or even no—energy intake may help enhance performance. If you train in the morning, intermittent fasting may compromise training adaptations, performance, says craigm.

When I was competing in bobsleigh, I weighed 95kg and trained for hours daily.