Carbs Before or After Workout: What’s Best for You?

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Carbs before or after a workout?

Written by Laoise Bennis

Carbs before or after a workout?

Nutrition plays a very important role when optimising athletic performance and recovery. Carbohydrates or carbs as they’re more commonly known are an essential part of this as they are the body’s preferred primary energy source during exercise, particularly at higher intensities.

This raises the question: Should you prioritise carbs before or after a workout? Let’s look at the science and some practical tips to help you make the best decision for your goals.

What is the science…how do carbs fuel our body?

The body uses a combination of carbs and fats during exercise of all intensities, but with a preference for glucose during moderate to high intensity exercise (Hargreaves & Spriet, 2018) . All carbohydrates are broken down into glucose when digested, This glucose is used directly for energy or stored as glycogen in the muscles and liver(Hargreaves & Spriet, 2018). Glycogen acts as a reserve fuel tank providing a quick and efficient energy source when exercising at a moderate to high intensity. (Burke et al., 2017)

If exercising for less than 60 minutes there is evidence from Dr Brian and his team to show that performance does not differ during shorter duration aerobic exercise between fasted and fed conditions. However in exercise >60 minutes pre-exercise feeding does enhance performance (Aird et al., 2018)

As glycogen stores are depleted, performance can suffer—resulting in fatigue, poor endurance, and diminished strength. There is lots of science that consistently demonstrates the correlation between adequate glycogen levels and improved athletic performance (Thomas et al, 2016). Athletes that consume carbohydrates prior to exercise have better endurance performance and delayed onset of fatigue compared to those who didn’t (Burke, 2021).

The science also shows that post-workout carb consumption accelerates glycogen replenishment, critical for recovery and muscle repair (Kersick, 2017) which begins your recovery for the next training session too!

Should you prioritise carbs before or after your workout?

The timing of carb intake depends on factors like workout intensity, duration, the intended adaptation of the specific session, and personal fitness goals. Let’s look at the benefits of pre- and post-workout carb consumption.

Benefits of carbs before a workout

Improved performance and stamina: Eating carbohydrates in the meal before exercise ensures glycogen stores are topped up, giving you the energy needed for sustained performance. Whether this is lifting heavy weights or running for an hour, having plenty of glycogen reduces the likelihood of early fatigue and helps you push harder.
Delaying fatigue: Pre-workout carbs are particularly beneficial for endurance activities lasting longer than 90 minutes. Consuming carbs 1-3 hours before exercise significantly enhances endurance by delaying glycogen depletion.

Timing and examples of pre-workout carbs

Timing matters when it comes to pre-workout carbs. Aim to eat a meal containing carbohydrates 2-3 hours before your workout or a snack 30-60 minutes beforehand. Some options are:

Complex carbs (2-3 hours before): Whole Supp shake, oats, rice/pasta/potato-based dish, or whole-grain bread.

Simple carbs (30-60 minutes before): Bananas, rice cakes with honey, fruit juice or a sports drink.

Complex carbs are especially key for longer workouts as they release more slowly. This is why we’ve included complex carbs in Whole Supp such as oats.

Why post-workout carbs matter for recovery

Don’t underestimate the value of carbs after your workout too, we need them for two main reasons:

1. Replenishing Glycogen Stores

After exercise, especially high-intensity or long-duration workouts, your glycogen stores are significantly depleted. Consuming carbohydrates post-workout helps restore these, ensuring your body recovers and your muscles are ready for the next training session.

2. Carbs and muscle recovery

Combining carbs with protein after exercise accelerates muscle recovery and repair. Evidence shows that a carb-to-protein ratio of 3:1 is ideal for optimising recovery (Kerksick et al. 2017).

Timing: The “Anabolic Window”

The first 3 hours post exercise is when the body is most efficient at nutrient absorption and glycogen replenishment. Consuming carbohydrates and protein within this window can significantly enhance muscle recovery and repair (Kerksick et al. 2017).

Quick options include:

Whole Supp or a smoothie with fruit and protein powder.
Chocolate milk
Rice with grilled chicken and veg
A piece of fruit and a flapjack

Tips for Selecting Carbs Based on Workout Type

So now you know a bit more about the benefits of carbs both pre / post workout. Let’s look a bit more at how you can select the right carbs for you. As a quick rule of thumb:

Endurance workouts (e.g., running, cycling): Prioritise a mix of simple and complex carbs before and simple carbs after with a meal within 2 -3 hours.
Strength training (e.g., weightlifting): Focus on pre-workout complex carbs in the meal before training for sustained energy without the need for a snack and post-workout simple carbs paired with protein.

The “best” carb timing and type depend on individual factors such as:

Workout type, duration, and intensity

Endurance athletes generally require more carbohydrates before and after workouts than those engaging in short, high-intensity sessions. For instance, a long-distance runner might need a carb-heavy meal before training, while a sprinter may only need a small snack.

Personal goals

Weight Loss: Keep total calorie intake in check while consuming carbs strategically to fuel workouts and recovery without overdoing it. Fun fact – every 1g of carbs your body stores is attached to 3-4g of water.

Muscle Gain: Pair carbs with protein post-workout to maximize recovery and muscle synthesis.

Improved Performance: Focus on consistent carb intake throughout the day to maintain glycogen levels.

Trial and Error

Experiment with different carb timing and types to find what works best for your body. Pay attention to how you feel during and after workouts and adjust accordingly. Even as a nutritionist who is training to be a dietitian I had to “hit the wall” or “bonk” once before the significance of how poor fueling and recovery really hit home. Making sure I eat well during the day to fuel an evening session or having something quick and easy like Whole Supp on my way home post 8-9pm swim with the Tri club means I can train hard and recover even harder.

Fuelling for exercise - a personal example.

Here you can see a picture of when I got the chance to wear a continuous glucose monitor as an experiment, I am a triathlete and I had a hard bike session on the turbo this day.I had a burrito for lunch - the brown rice and a white wrap were the carbs causing a spike before the carbohydrates got packed away as stores. A homemade cereal rice krispie bar as a snack pre workout caused a smaller spike in my circulating blood sugar.

The red square is where I started exercising. The circulating glucose in my blood is normal but it will start to be used up as I was completing a high intensity session. In order to maintain homeostasis the glucose stores in my glycogen are released and cause a rise - I was also consuming a carbohydrate drink during my session. This big spike shows I have lots of circulating glucose in my blood to fuel my muscles. This may help you visualise how we use energy and why we need to fuel well. Having full glycogen stores means we have a store of energy during endurance exercise such as a high intensity cycling session that I completed during this graph. Running out of carbohydrate availability in our glycogen stores is more commonly known as “a bonk”.

To wrap up

Carbohydrates are essential for fuelling workouts, enhancing performance, and supporting recovery. Pre-workout carbs improve stamina and delay fatigue, while post-workout carbs replenish glycogen stores and accelerate recovery. There’s no one-size-fits-all approach—your ideal carb strategy depends on your workout type, goals, and individual needs.

Start experimenting with your carb intake and pay attention to how your body responds. Whether you’re fuelling for a marathon or recovering from a heavy lift, carbs are your friend in achieving peak fitness.

Aird, T. P., Davies, R. W., & Carson, B. P. (2018). Effects of fasted vs fed-state exercise on performance and post-exercise metabolism: A systematic review and meta-analysis. Scandinavian Journal of Medicine & Science in Sports, 28(5), 1476–1493. 10.1111/sms.13054

Burke, L. M. (2021). Nutritional approaches to counter performance constraints in high-level sports competition. Experimental Physiology, 106(12), 2304–2323. 10.1113/EP088188

Burke, L. M., Luc J C van, L., & Hawley, J. A. (2017). Postexercise muscle glycogen resynthesis in humans. Journal of Applied Physiology, 122(5), 1055–1067. 10.1152/japplphysiol.00860.2016

Hargreaves, M., & Spriet, L. L. (2018). Exercise Metabolism: Fuels for the Fire. Cold Spring Harbor Perspectives in Medicine, 8(8), a029744. doi: 10.1101/cshperspect.a029744. 10.1101/cshperspect.a029744

Kerksick, C. M., Arent, S., Schoenfeld, B. J., Stout, J. R., Campbell, B., Wilborn, C. D., Taylor, L., Kalman, D., Smith-Ryan, A. E., Kreider, R. B., Willoughby, D., Arciero, P. J., VanDusseldorp, T. A., Ormsbee, M. J., Wildman, R., Greenwood, M., Ziegenfuss, T. N., Aragon, A. A., & Antonio, J. (2017). International society of sports nutrition position stand: nutrient timing. Journal of the International Society of Sports Nutrition, 14(1), 33. 10.1186/s12970-017-0189-4

Thomas, D. T., K. A. Erdman, and L. M. Burke. 2016. “American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance.” Medicine & Science in Sports & Exercise 48: 543–568.