The importance of nutrient timing: how and when to fuel your training for optimum performance

As an athlete you demand the very best from your body. Performance is key and every advantage is important. No matter how small.

So if there was a way to boost your endurance and strength, delay fatigue and even enhance your recovery without changing your diet or your training regime. You’d be all over it, right?

Well, there is. It’s all about nutrient timing.  

Because peak performance is not just a case of what to eat to fuel your training, but when.

In this guide we’ll show you how by strategically manipulating your food and supplement intake you can transform the way you perform on the track, in the ring or at the gym.

Key points:

  • Nutrient timing enhances both performance and recovery by manipulating the absorption of nutrients pre and/or post-exercise.
  • Carbohydrates are the most popularly researched nutrients in relation to timing of ingestion for endurance athletes.
  • Carb-loading before exercise and carb ingestion after can improve performance and recovery.
  • Post-workout carbs should be consumed within a 30-minute period to optimally replenish glycogen.

What is nutrient timing?

To get the best from your body you need to fuel it the right way. This means flooding your cells with proteins, wholegrains, fruits and vegetables.

Calorie intake supports activity levels and wholesome, nutritious foods will help you support your performance goals. 

But nutrient timing isn’t so much to do with what you eat, but when.

According to a recent position statement from the International Society of Sports Nutrition (ISSN), nutrient timing incorporates the use of methodical planning and eating of whole foods, fortified foods and dietary supplements.

Put simply, by timing your intake of food and by manipulating the ratio of macronutrients it is possible to enhance performance, recovery and muscle tissue repair.

There’s also a huge psychological to it element too. With advocates of nutrient timing suggesting it can also have a positive impact on mood and energy levels.  

Nutrient timing focuses on eating at specific times around exercise. To have the maximum impact on your adaptive response to acute physical activity

Nutrient timing has been around since the 1980s. Researchers found that when athletes manipulated carbohydrate intake around exercise, muscle glycogen stores increased and physical performance improved during time trials1

At around the same time, scientists realized that increasing carbohydrate intake immediately post-exercise led to significant improvement in glycogen synthesis rates - an important part of the recovery process2.

Since these innovations, nutritionists, performance coaches and researchers have spent hours analyzing the timed effects of different nutrients and supplements on exercise performance.

Why is nutrient timing important?

Athletic success is built on fundamentals. As you adapt to training and support your activity levels with the right foods, your performance will improve. But after a while, in order to really push your progress you will need another strategy layered on top.

That’s where nutrient timing comes in.

Note: It’s important to realize that nutrient timing is aimed at athletes who have already reached a good level of physical fitness. And follow a healthy diet that supports their body composition and athletic performance.

In other words, nutrient timing suits those that have already nailed their calories and macros. There’s no advantage in timing nutrient intake if those nutrients aren’t going to support your progress.

 

Nutrient timing techniques provide a competitive edge in athletes whose physiques are primed.

If you’re just starting your journey to improved athletic performance, focus your attention on overall energy intake and exercise to begin with. And build in timing manipulation as you progress.

There’s no advantage in timing nutrient intake if those nutrients aren’t going to support your progress

It’s not just the what, but the when.

As time has passed and research has grown, we now know that nutrient timing provides several key benefits:

  • Enhanced adaptation to exercise
  • Better repair and recovery
  • Increased work capacity
  • Improved performance.

Energy balance and food choices are key indicators of a healthy, performance-optimized diet. But evidence shows that timing is too. Because your body utilizes nutrients differently depending on when they are ingested.

Athletes are always looking for that extra edge over competitors. Nutrient timing is a key weapon in your performance arsenal. Providing your body with that push it needs to be successful

The research on carbohydrate nutrient timing

Training, competitions and workouts that last 60+ minutes, or include multiple bouts of high-intensity exercise rely on glycogen storage for fuel.

It is therefore important to put strategies in place to help maximize the amount of glycogen stored within the muscle and liver. A diet rich in carbohydrates is key of course, but emerging research has shown that timing carb ingestion is important to maximize overall effects.

Note: While strength and team sport athletes require optimal glycogen stores to improve performance, most of the research into nutrient timing using carbohydrates has been conducted on endurance athletes.

Find out more about how glycogen storage can affect exercise performance in our dedicated guide... 

Athletes can utilize carb-loading to enhance glycogen stores

Ever since the late 1970s, coaches have used a technique called carb-loading to maximize intramuscular glycogen3. The technique varies from athlete to athlete (and from sport to sport), but the most traditional method of carb-loading is a 7-day model:

  • Periods of high-volume training for 3-4 days with limited carb intake
  • Followed by a ‘loading phase’ of 3-4 days (ingesting between 8-10 grams per kilo of body weight) while decreasing training.

There are variations on this model too. Including the classic 6-day version and 3-day variation where carbohydrate intake is increased, but exercise isn’t included during loading phases. There’s even a 1-day version which essentially involves resting while eating high carbs.

This technique has been shown to result in supersaturation in glycogen stores - much more than through a traditional high carb diet4. The idea is to deplete glycogen stores with a low carb diet and high-volume training regime. Then force muscle cells to overcompensate glycogen storage.

Carb loading has been found to improve long-distance running performance in well-trained athletes, especially when combined with an effective tapering phase prior to competition5. Evidence shows that female athletes may need to increase calorie and carb intake in order to optimize the super-compensatory effect6. This is purely down to physiological differences.

Delayed fatigue, prolonged endurance

It has also been shown to delay fatigue during prolonged endurance training too7. This is thought to be due to higher levels of glycogen stores, which not only provides more substrate energy but also decreases indirect oxidation (via lactate) of non-working muscles.

It’s worth noting that carb-loading only seems effective in trained athletes, as glycogen supercompensation doesn’t occur as well in untrained individuals. In fact, trained athletes can also super compensate without the low-carb phase too - providing a rationale for a more ‘modified’ approach to carb-loading.

Carb-loading as part of a nutrient timing protocol can lead to glycogen supercompensation and improved endurance performance

Strategies for carb-loading involve high glycemic carbs during the loading phase, which helps to increase carb intake - but limit fiber (high fiber will lead to bloating and discomfort). Focusing on familiar foods is key in order to limit unwanted adverse effects.

Foods to focus on could include:

  • White bread and pasta
  • Potatoes
  • Juice and sports drinks
  • Candy, cakes and applesauce
  • Fruit

Both strength and endurance athletes can benefit from pre-workout carbs

Carb-loading on the days prior to competition, or high-intensity training is one strategy to help optimize athletic performance. Another is to ensure carb intake is increased in the hours beforehand.

High-carb meals have been shown to improve cycling work rate when taken four hours prior to exercise by enhancing glycogen synthesis8. Even though the meal had been fully digested prior to exercise, glycogen storage was still increased by 42%.

It is not recommended to eat a high-carb meal in the hour immediately prior to exercise due to gastric load and potential negative effects, such as rebound hypoglycemia9.

Instead, high-carb snacks, supplements or smaller meals can be used instead - and combined with fluids to optimize hydration. Many athletes are turning to carb-based supplements to fuel up prior to exercise. Mostly because glycogen synthesis is the same compared to food10, 11 but with fewer potential side effects.    

Liquid carb supplements may provide a better option for athletes as a pre-workout tool

Similar results have been seen in strength athletes too.

A study published in the Journal of Strength and Conditioning Research12 found that weightlifters who took part in high-volume strength workouts benefitted from carb supplementation prior to, during and also after each workout.

The authors suggested that because intermittent activities rely on anaerobic glycolysis to provide fuel, adequate glycogen stores needed to be achieved prior to exercise in order to optimize performance.

This has been backed up in other studies, showing pre-workout carbs taken an hour or two prior to strength exercise. Low carb intakes before weight training have resulted in loss of strength [9] as well as force production and early onset of fatigue13.

Strategic fuel consumption in the form of pre-workout carbs can help to maximize muscle and liver glycogen levels and enhance strength and endurance capacity

Post-workout carbs replenish energy and help with recovery

The main objective after a training session or competition is to promote recovery. This process is undoubtedly underpinned by carbohydrate intake, as replenishing glycogen levels is a priority for all athletes.

Early research showed that glycogen stores could be replenished in half the time if a large dose of carbohydrate could be ingested within 30-minutes post-workout14.

Since then, several studies have found similar results. Collectively, it seems that ingesting between 0.5 - 1 gram of carbohydrates per kilogram of body weight within a 30-minute post-exercise window is the best strategy to replenish energy stores.

Additionally, glycogen can be completely replenished with 24-hours if the athlete achieves a carb intake of over 8 grams per kilogram of body weight15.

Post-workout carb intake should be a priority for an athlete in any of following three scenarios:

  • One who requires fast glycogen replenishment
  • One who has taken part in glycogen-depleting exercise
  • Or when inadequate amounts of carbohydrate were administered pre-workout.

To maximize glycogen re-synthesis after exercise, a carbohydrate supplement should be consumed immediately after competition or a training bout

Takeaway…

Peak performance is not just a case of what you eat, but when you eat it.

Nutrient timing can help athletes who want to optimize performance and recovery.

Muscle glycogen depletion can lead to poor performance and negatively impact on muscle repair. This is where carb-loading in the days before exercise and strategic carb intake in the hours immediately after, can transform strength, endurance and recovery.