ISSA, International Sports Sciences Association, Certified Personal Trainer, Carbs, Carbs: Hurting And Slowing Down Your Workout

Carbs: Hurting And Slowing Down Your Workout

Reading Time: 5 minutes 3 seconds

By: Christina Klein

Date: 2016-09-19T00:00:00-04:00

Should you really be cutting back on carbs to achieve weight loss and muscle mass?

Ever since low-carb diets exploded onto the weight-loss scene, carbohydrates have been demonized, avoided, and targeted as a dietary evil.

Should you really be cutting back on carbs to achieve weight loss and muscle mass?

But here's the truth: we all need carbohydrates in our diets, every single day.


In two of our recent blog posts ("How much protein do I really need?" and "How Much is Too Much? Protein Myths Busted"), we tackled the often controversial question of just how much protein you need before and after a workout. Here, we give you the truth about carbohydrates, how much you need, and how they can promote performance and recovery.

The Before Factor

Whether you're working out to gain muscle mass, to lose fat, or for better performance, to achieve your goal you need sustained energy.

One of two things happens when you run out of steam in the middle of a workout:

  • You stop early and don't train for as long as you had planned.

  • You finish your workout, but hold back and don't push as hard.

In either case, running out of energy during a workout means a compromised workout.

One method of sustaining energy throughout a workout is by maximizing glycogen storage.

Glycogen is the stored sugar in your liver that is released when you need more energy. If you don't have enough stored up, your workout will go south quickly.

Guess what gives you that perfect glycogen build up before a workout?


There are many different methods for maximizing glycogen storage. Besides carbohydrates, high-fat diets have been proven to increase endurance during the performance as well.

For today we will focus on how carbohydrates can maximize glycogen storage.

The After Factor

Guess what is also important after a workout?

You got it: carbohydrates.

After a training session, glycogen needs to be replenished. If it's not, you could be seeing muscle breakdown, slow muscle recovery, and diminished performance overall.

How do you time carb intake before and after a workout?

To build up enough glycogen ahead of a workout for sustained energy, you need to get the timing right.

Here's what the research says about pre-workout carb-loading:

In a 2014 study by Ormsbee et al., the performance of cyclists was measured, and results concluded that when consuming carbohydrates one hour before exercise, there was a larger drop in the athlete's blood sugar, which led to impaired performance.

In the same study by Ormsbee et al., carbohydrates were ingested two to three hours before a workout, athletes were able to maintain glycogen storage, giving them enough sustained energy for the entire cycling event.

What about post-workout carbs?

Two separate studies conducted by Berardi (2006) and Ormsbee (2014) found that when simple carbohydrates such as glucose were consumed within 60 minutes of exercise, there was a significant increase in muscle glycogen replenishment and a decrease in muscle recovery time.

When athletes waited longer than 60 minutes to replenish with carbs, they experienced longer muscle recovery times because of depleted glycogen.

Takeaway: For enough sustained energy to complete an effective workout and for maximum muscle recovery, consume complex carbs such as brown rice, two to three hours before a workout and a simpler carbohydrate such as glucose within one hour after a workout to reboot energy stores.

What Kinds of Carbs Should You Be Eating?

There are two basic types of carbohydrates: simple and complex. Simple carbohydrates include simple sugars like glucose, fructose (fruit sugar), and sucrose (table sugar).

These simple carbs provide the quickest source of available energy. Think of the kid who starts bouncing off the walls after eating a piece of candy or drinking a soda.

For quick recovery of glycogen stores, simple carbs are your preferred source of energy post workout. They can also provide you with quick bursts of energy when you're flagging during a workout.

Complex carbohydrates, like starch, are found in plant-based foods: whole grains and starchy vegetables such as potatoes. Complex carbohydrates provide sustained energy over longer periods of time, and also help replenish glycogen after training.

Takeaway: Complex carbs are your best choice for sustained energy two to three hours before a workout. They are also a good choice for the post-workout recharge, but can be combined with simple carbohydrates for a quick fix.

How much do you need to eat pre- and post-workout?

Exactly what portion size you need depends on your current weight, your goals, and the purpose of a training session.

If your goal is to get through a long cardiovascular endurance workout, you need more glycogen build up in advance.

If your goal is strength training or resistance training, you don't need quite as much in your glycogen storehouse.

Likewise, for post-workout carb intake, you need more to replenish after a long endurance workout than after a strength training session.

To be more specific, in one study (Jeukendrup, 2014), the recommended pre-workout intake of carbs for endurance is 60 grams per hour for workouts lasting two to three hours, and up to 90 grams per hour for longer endurance events. Anything less than two hours requires less than 60 grams of carbs pre-workout.

Takeaway: A general rule of thumb is to experiment with your body and start by trying to consume between 0.5 and 1.0 grams of carbs per kilogram of body weight before and after workouts, more for endurance, and less for strength training.

What about combining carbs and protein?

Protein, as we talked about in previous posts ("How much protein do I really need?" and "How Much is Too Much? Protein Myths Busted"), is another important nutrient for muscle building and recovery. But here's what you really want to know:

Should you eat proteins and carbs together?

The answer is a definite yes. Carbohydrates and protein work together to provide:

  • Sustained performance.

  • Increased glycogen storage.

  • Faster recovery times.

Westcott and Loud (2013) discovered that consuming a combination of carbohydrates and protein led to increased muscular gains.

Bartlett et al. (2015 found that when athletes consumed fewer carbs with protein supplements, they experienced more muscle breakdown. And, when they continued to exercise without carbohydrates they lost more skeletal muscle mass.

Carbohydrates and protein work together for faster muscle recovery, especially after strength training and muscle-building exercises.

Takeaway: Add about 0.5 grams of protein per kilogram of body weight to your pre- and post- workout carb snacks or supplements.

The bottom line is that you NEED Carbohydrates both pre- and post-workout for sustained energy, improved performance, and better muscle recovery.


Bartlett, Jonathan., Hawley, John., Morton, James. "Carbohydrate availability and exercise training adaptation: Too much of a good thing?" European Journal of Sport Science15.1 (2015): p 3-12

Jeukendrup, Asker. "A Step Towards Personalized Sports Nutrition: Carbohydrate Intake During Exercise" Journal of Sports Medicine44.1 (2014): p 25-33

Ormsbee, Michael. Bach, Christopher. Baur, Daniel. "Pre-Exercise Nutrition: The Role of Macronutrients, Modified Starches and Supplements on Metabolism and Endurance Performance" MDPI Nutrients6.5 (2014): p 1782-1808

Westcott, Wayne., Loud, Rita. "Enhancing Resistance Training with Protein/Carbohydrate Supplementation" ACSM Health and Fitness Journal17.2 (2013): p 10-14

Berardi, John., Price, Thomas., Noreen, Eric., Lemon, Peter. "Postexercise Muscle Glycogen Recovery Enhanced with a Carbohydrate-Protein Supplement" ACSM Medicine and Science in Sports and Exercise(2006): p 1106-1113

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