How Much Sugar Should a Runner Eat?

A runner pulls a GU gel from her pack

Just a few decades ago, endurance athletes (along with the general public) labeled fat as the bad guy. Today, carbohydrates (carbs) are in the hot seat.

According to the rumors, carbs--namely sugar--are said to be unhealthy, cause weight gain, reduce the body’s ability to burn fat, contribute to diabetes, insulin resistance and cravings, cause energy crashes and, finally, negatively affect performance. Yikes! No wonder everyone is avoiding carbs like the plague. However, not all rumors you hear are true. And, when it comes to proper fueling, carbs actually aren’t the bad guys they’ve been made out to be.

The role of carbs

Carbs are essential for optimal health and serve as the primary fuel for the body. Before you even lace up your shoes to run, your body requires 120 grams of carbs (about 500 calories) per day simply to fuel your brain, support your central nervous system and maintain red blood cell production and immune health.

During exercise, your body utilizes carbs for energy in the form of glucose. This fuel assists in fat metabolism, delays fatigue, promotes recovery and supports the central nervous system.

In high-intensity exercise (like a tempo workout), carbs are responsible for converting fat to glucose quickly; fat is burned in a carbohydrate-fueled flame. The proverbial “wall” or “bonk” runners refer to, occurs when glycogen (long-chain glucose stored in the muscle) reserves are depleted. And, in the absence of glycogen, no fuel is available to convert fat to usable fuel quickly.

On top of this, the body’s glycogen stores are limited. Fully stocked, your tank holds enough glycogen for approximately two hours worth of effort at moderate intensity. Keep in mind, the higher the effort, the more carbs you use, and the faster you burn through glycogen stores.

So, what you eat day to day and the timing relative to exercise directly impacts how much glycogen you have available in your “gas tank” at any given time. Adequate carb intake that matches activity level can safeguard your glycogen storage, muscle tissue, support blood sugar levels during exercise, optimize recovery and protect your immune system.

So how do you know how much to eat?

A spread of healthy carbohydrate based food

Daily carbohydrate recommendations

Some of the healthiest and fastest runners in the world consume a carbohydrate-rich diet, including the elite Kenyan runners who dominate the distance running world.

In conducting research for his book, “The Endurance Diet,” dietitian, writer and endurance runner, Matt Fitzgerald writes that elite Kenyan runners get 76 percent of their daily calories from carbs that come from fresh, unprocessed food sources.

While it’s OK to eat processed food on occasion, if you prioritize wholesome, nutrient-dense carb sources in place of processed, refined, or nutrient-poor choices most of the time, you can radically improve running performance and feel better, too. That’s because these types of carbs are complex, which means they break down into glucose a bit slower than simple sugars and provide vitamins, minerals and fiber. Being selective with your carb choices and strategic about the timing of your consumption, helps too.

For example, a morning runner should include carbs at breakfast and lunch but can taper off carbs at dinner and include more veggies and fruit. Exception: if it’s the night before a long, intense workout or race, don’t skimp on complex carbs at dinner.

A runner removes his mask to drink from a handheld bottle

Sports nutrition

The confusion is real when deciphering why it’s OK and even encouraged to fuel with sugar during a run, but it’s not OK to eat simple sugar any time you want. What’s the difference? There’s a big difference.

The body runs on various energy systems, and at any given time, we are always burning a percentage of both fat and sugar. The lower the output, such as sleeping, the higher the percentage of fat utilized. The higher the output, such as running all-out repeats on the track, the more sugar we burn. An easy, aerobic run that is fully conversational will utilize approximately 50 percent carbs and 50 percent fats.

During an interval run, you may go from aerobic to anaerobic and back to aerobic efforts, drastically changing from one metabolic system to the next, which utilizes glucose pulled from stored glycogen – quickly. Therefore the sugar consumed during this run will be broken into glucose rapidly since there’s no protein or fat to slow down gastric emptying, turned into blood glucose, and quickly taken up by the working cells for energy.

In layman’s terms, the sugar you consume in training and racing is immediately used for energy and will enhance your performance.

Sugar can also restock glycogen storage and spur along recovery when consumed after running long distances or intense workout. If glycogen stores aren’t refilled after depletion, it puts the body under stress, increasing cortisol. In turn, muscle is broken down for energy, the very thing the runner wants to avoid.

However, when the body is at rest while sitting at your desk or watching a movie, it is burning primarily fat. During this state, the muscle cells are not working hard and don’t need to utilize sugar for quick energy. So, the sugary snacks consumed, in this case, will be converted to fat for storage and future use.

Carbs are an important part of a runner's diet

Diet and fueling recommendations for improving your carb intake

Nutrient-dense carbohydrate choices (to name a few):

  • white/sweet potatoes
  • brown/wild rice
  • quinoa
  • oatmeal
  • winter squash
  • beans
  • peas
  • lentils
  • legumes
  • corn
  • fruit
  • root vegetables


It’s worth mentioning that fruit has been wrongly lumped in the same category as sugary candy. Nothing could be more misleading! Fruit contains naturally occurring fructose, fiber, micronutrients and water, whereas prepackaged candy has sugar – and little else. Candy is often dyed, flavored table sugar (sucrose). Fruit has been labeled nature’s vitamins, minerals and dessert all wrapped up in one. Include fruit in your daily diet and your body will thank you.

Daily carb recommendations based on volume/intensity

Low intensity <1 hr/day

3-5 g/kg/day*

Moderate intensity 1 hr/day

5-7 g/kg/day*

Moderate to high intensity 1-3 hr

6-8 g/kg/day*

High intensity 4-5+ hr/day

8-12 g/kg/day*

*Remember as training volume and intensity increase so does the need for carbohydrates


Carbohydrate portions based on training phase

Another way to manage appropriate carb intake based on training load is the portion sizes on your plate.

Off-season or lighter training days

25 percent of your plate

Intense peak-training days, race phase

50 percent of your plate

Carbohydrate recommendations during activity

To maintain blood glucose levels and keep glycogen stores from hitting empty, supplementing with sports nutrition products is wise during prolonged and/or intense training sessions.

Low intensity for 45 to 75 minutes

No fueling is required*

Moderate to high intensity

up to 75 minutes

Hydrate and fuel if needed


high intensity up to 2.5 hours

30-60 grams per hour

*Water is recommended. Electrolytes may be necessary for extreme sweating. Low intensity includes activities such as golf, yoga, and walking the dog around the neighborhood.

Prioritize your recovery

A woman fills her cup with a recovery drink

Post-workout recovery fuel is designed to speed up the repair of damaged muscle tissue, replace glycogen/energy stores and promote physical adaptation. Immediately following a training session, muscle cells are open, insulin sensitivity is elevated and the body is primed to absorb simple sugar and protein. The faster you refill the tank, the faster the body gets the green light to burn body fat.

The optimal recovery window to jump-start the process is short, just 30 minutes.

As time ticks, insulin sensitivity declines, and muscles take longer to absorb glucose from the bloodstream; therefore, glycogen storage is less than optimal. These hormonal reactions create a stressful environment for the body; hence, cortisol is released, which promotes fat storage especially in the abdominal area.

By consuming a recovery snack within 30 to 45 minutes, you can extend your ability to effectively refill glycogen stores up to eight hours by snacking on carbs every couple of hours.

If you skip a recovery snack, then two to two and a half hours post-workout, your glycogen stores fall to less than 50 percent. This lack of glycogen stores doesn’t bode well for recovery, performing well in tomorrow’s training session, or for the tidal wave of cravings that will hit you later.

To be clear, refueling is not essential after an easy-recovery workout or a stroll after dinner. Consuming regular, well-balanced meals will suffice on easy or rest days. The recovery fuel is intended for intense, extended, or strenuous workouts, (also between multiple workouts in one day), where you are feeling depleted and wrung out.

What to eat after a workout

A green mango smoothie for runners

Within 30 to 45 minutes after a workout, aim for a 3:1 or 2:1 (Carb/Protein) ratio.

Men follow a 3.1 ratio, while women need a tighter 2:1 ratio immediately following workouts for anabolic triggers to repair and aid muscle growth.

It’s important to include both carbs and protein because they work in tandem to boost glycogen storage, reduce inflammation, and boost immunity. Research shows that athletes who consume a recovery snack with Carb/Protein restock glycogen stores four times faster than those who refuel with carbs alone.

Recovery guidelines based on the duration of activity

Aerobic effort of 1 to 1.25 hours

20+ g protein and 40g carbs

Moderate to High Intensity of 1 to 3 hours

20-30g protein and 40-90g carbs

Long-Endurance of 3 to 10 hours

Within 30-45 min: 25 to 30g protein and 50 to 90g carbs

2 hours after: 20 to 30g protein and 40 to 90g carbs

4 hours after: 20-30g protein and 40-90g carbs

For example, a 120 pound (54.5kg) athlete who ran for 3 hours would refuel with 20g protein and 40 to 60+ g carbs within 30 to 45 minutes, followed by a balanced meal within 90 minutes.

It’s common to have a decreased appetite following a hard workout. If you don’t feel hungry, refuel with a cold liquid that sounds refreshing and goes down easy.

Recovery options

Smoothie with 20g whey protein

16oz low-fat chocolate milk or Greek yogurt for added protein

Fat-free Greek yogurt with a banana and grapes

Bagel with low-fat spread (nut butter) (V)*

Smoothie with pea or soy protein, frozen bananas or mangos, fat-free yogurt or sweetened-almond milk (V)*

Peanut butter and jelly sandwich (V)*

*(V)=Vegan option

The Final Word

Knowledge is power and the more you understand carbohydrates’ role in supporting your body, health, and active lifestyle, the closer you will be to achieving your goals. To recap, not all carbohydrates are created equal, and carb-timing is key to proper adaptation, recovery, and body composition optimization.

Consume carbs during your most active time of the day. Limit refined, sugary snacks and desserts but if you can’t kick that nagging craving – go for that sweet treat right after a workout or include post-meal to diminish the hormonal and blood sugar response, therefore, reducing the fat storage effect.

Reducing or eliminating carbs will not help you accomplish your goals for performance and wellbeing. In the long run, limiting a macronutrient or following a diet regimen that results in a negative energy balance will leave you empty and unsuccessful.

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