The Glycemic Index & Exercise

“I don’t eat carbohydrates because I’m trying to lose weight”. “ Carbohydrates are bad for you”
…only some of the many lines I’ve picked up on when conversing with people at the gym.

From an exercise and recovery standpoint, carbohydrates are an essential macronutrient. They’re the main source of energy for the body. If you workout regularly, you need them. No carbohydrates, no energy to fuel your workout.

Where carbohydrates may be ‘bad’ for you lies in the quality of carbohydrates you eat and the timing you eat them as well. Having said that, understanding the carbohydrate response in the body, otherwise known as the Glycemic Index, and how you can associate this with your exercise and nutrition routine will make a world of a difference.

The Glycemic Index: What is it?

Simply put, the Glycemic Index (GI) represents the rise in blood sugar after the consumption of a carbohydrate food source (remember, carbohydrates transform into sugar (glucose) upon digestion). Foods with a low GI do not raise blood sugar levels drastically, maintaining stable blood sugar levels, while high GI foods cause a spike in blood sugar levels.

Numbers are used to represent the GI of foods. They are categorized in the following manner:

Low: < 55

Medium: 55- 69

High: > 70

For general health and well-being, I always advise consuming low GI carbohydrates. This entails, among others, whole-wheat grains/pasta/rice/bread, quinoa and sweet potato. Low GI foods maintain blood sugar levels and do not cause a rapid rise or decline – thus supplying the body with a constant flow of energy.

On the flip side, high GI foods should be avoided on an everyday basis (except during one occasion, which I’ll explain to you next). Because high GI carbohydrates raise blood sugar levels rapidly they trigger the release of insulin. Insulin then uses up some sugar for energy, but leaves some untouched as well. These unused sugars will then be stored as fat.

The Glycemic Index and Exercise

Now that you’ve gotten the gist of GI foods and the sugar response, it’s important you understand when to consume certain foods of different GI levels.

Like I said, it’s best you consume low GI carbohydrates the majority of the time, especially if you don’t exercise. If you do exercise, however, always consume low GI carbohydrates prior to your session. Such foods keep blood sugar levels stable while steadily supplying the body with energy.

Not only will you avoid a rapid spike in blood sugar levels, you’ll also prevent a rapid decline as well. The slow and steady release of energy will allow you to sustain exercise for a longer period of time without experiencing a ‘crash’.

Now, I’ve mentioned ONE occasion in which you may consume high GI foods and that’s after exercise. The rationale behind this stems from the notion of recovering the carbohydrates used during exercise in the quickest manner possible.

Again, because high GI foods cause a spike in sugar levels, consuming such foods after exercise will not only allow a quick replenishment of carbohydrates to ready the muscles for subsequent sessions, but also ‘spare’ muscle protein.

After exercise, stored carbohydrates may be partially or completely depleted depending on factors such as pre-exercise carbohydrate stores and exercise duration and intensity. The quick release of insulin as a result of high GI foods will replace the carbohydrates (sugar) used up during exercise and commence the recovery process.

If carbohydrates are not replenished after exercise, and preferably in the immediate hours post-exercise, muscle protein breakdown may occur to feed the body with protein needed for recovery.

Hence, allowing for a quick replenishment of carbohydrates via the consumption of high GI foods serves as the only logical time to efficiently replenish carbohydrate stores while avoiding muscle protein loss. Otherwise, stick to low GI foods.

Just a quick note, if you do consume low GI carbohydrates after exercise, you’ll still experience the same affect on muscle recovery as if you were to consume high GI carbohydrates – but at a relatively slower rate.

To reinforce, carbohydrates are not bad for you! There’s no need to negate them from your diet. I don’t advise you do so anyway. The key to consuming carbohydrates without any negative influence on body weight nor exercise performance is to be mindful of the type and timing of carbohydrates consumption.

Through a simple and informed explanation, I hope you now understand the concept of the GI response in the body and its applicability within an exercise context. I always emphasize on the idea of eating right but also eating smart. After reading this post, you now can be healthy and smart with your carbohydrates intake.

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