Understanding How Carbs Can Impact Performance


Carbohydrates are a macronutrient, meaning a larger nutrient class, which (for the most part, must be obtained externally. Carbohydrates are often mistakenly thought of as sugars.

Yes, sugar is a carbohydrate. However, spinach is predominantly water and fiber but is also considered a carbohydrate. In short, understanding what carbohydrates are, along with their classes and application, can guide a gym-goer or athlete to consume the carbs that will help them to perform their best.

Carbs 101

Carbohydrates are molecules of carbon and hydrogen. They are classified as sugars (digestible) and fiber (somewhat non-digestible). Examples of digestible forms are:

Understanding How Carbs Can Impact Performance - Fitness, fitness, gluten free, inflammation, glycemic index, cardiovascular disease, sugar alcohols, fiber, digestion, blood glucose

Non-digestible forms of carbohydrates include soluble and insoluble fibers. For the athlete or common gym-goer, understanding how the grain, legume, and vegetable balance plays a role in proper nutrition can help them make better choices.

Simple and complex sugars are in most foods we eat, such as:

  • Oats
  • Fruits
  • Rice
  • Potatoes

Added sugar and sugar alcohols are manufactured from simple and complex sugars to meet a need. An example of added sugar may be:

These added sugars and sugar alcohols are best avoided or limited due to their link to cardiovascular disease.

Sugar alcohols, often found in fermented products such as beer, have no caloric value and are linked to weight gain. Carbohydrates, from this understanding, metabolically have a substantial effect on the human body.

Carbs and Humans

The human brain alone utilizes 40% of the human body’s glucose (a simple sugar). Muscle tissue has a simple sugar store called glycogen, and thus without sufficient carbohydrates, force output suffers.

What might be far more critical to you as a reader, is the effect on your daily training and which carbohydrates work well and at which times. Three things one must denote to utilize carbohydrates effectively:

  1. Glycemic index
  2. Gastric emptying time
  3. Sensitivity and timing

Humans typically have an excellent tolerance for differing forms of carbohydrates, and thus, diversifying your carb intake is pivotal to longevity.

Carbohydrate Sensitivity

I am, predisposed to coeliac disease. So much so that my go-to carbohydrate source is gluten-free cream of rice. Coeliac is an autoimmune disorder ( the body fighting itself) by which the digestion of wheat-based products causes damage to the intestinal/gastrointestinal (GI) tract, more specifically inflammation due to gluten.

Carbohydrate sensitivity needn’t be this severe, however, in terms of digestion ease, we understand that the High Glycemic Index (causing a spike in blood glucose) typically is shuttled through the body quickly. In contrast, low to medium GI foods remain longer in the GI tract.

Nevertheless, people often do not consider foods that provide the best yield in rebuilding glycogen stores and digestibility. Sensitivity is best done piecemeal. Try three carbohydrates that are not highly processed, such as:

  • Oats
  • Jasmine rice
  • Sweet potato

Understanding How Carbs Can Impact Performance - Fitness, fitness, gluten free, inflammation, glycemic index, cardiovascular disease, sugar alcohols, fiber, digestion, blood glucose

Utilize this source as your carb source for 48 hours. Record bloating, energy level, force output, and do this with alternate sources of carbohydrates.

Ultimately, your ideal is carbs that will give you the best pump in the gym, force output, promote proper digestion without bloating, and is readily accepted by the body. For those interested, insulin sensitivity goes hand in hand with carbohydrate sensitivity.

Carbs and Stomach Happiness

Gastric emptying time refers to how quickly the stomach and intestine can move food. This movement is typically measured in isolated environments such as the doctor’s office via ultrasound. Gastric emptying is affected by the types of foods ingested.

Protein, for example, takes more energy to metabolize but is classified into fast-digesting and slow-digesting, such as whey protein versus casein, respectively. For carbohydrates, this exists as well.

Most high glycemic index foods such as jasmine rice move through the colon quickly. For science buffs, dextrose and amylopectin are examples of fast-digesting carbs that are longer chained carbs found in supplement powders typically.

Slower digesting carbohydrates are low or medium GI. An example would be a sweet potato. This speed of digestion is important for timing meals. You wouldn’t want to have a slower digesting carbohydrate closer to a workout, which can mean 30 or even 120 minutes before training.

Carb Timing

As previously discussed, carb timing peri-workout is vital to understand in athletes and typical gym-goers based on their training. Longer training sessions benefit from fast-digesting carbs before training and a combination of fast and slow carbs post-training, especially if the next meal will be a significant time away (4+ hours).

This is the case as the body during training expresses a protein called Insulin-like growth factors 1 and 2 (IGF-1), which increases the human body’s sensitivity to the release of insulin. This is important in nutrition as the faster-digesting carbohydrate; the faster muscle glycogen can be recovered.

However, this is different based on the amount of adipose tissue in the individual. As such, in diabetic individuals, for example, who are overweight faster-digesting carbs may not be the go-to pre-workout as the body is not prepared to promote lipolysis; instead, it will use the incoming carbs to fuel the workout.

Seek a coach and an endocrinologist’s advice on where you stand. Nutritionists and dietitians are helpful but seek out sports nutritionists or dietitians who specialize in sports nutrition, not one for the general public.

A Friendly Carb PSA

  • Myth #1: Carbs before bed are helpful.

    This is one of the most nonsensical things I’ve heard for athletes and people who train consistently 4-8 days a week. As previously discussed, high GI foods such as Pop Tarts or jasmine rice right before bed pump your bloodstream full of glucose. This scenario would be great if you’re about to do a nighttime competition, however, not before bedtime for the average healthy sleeper, as discussed by Afgahi et al., 2007.
  • Myth #2: Carbs are evil.

    Carbs are structural and energy-producing machines, non-responders, please leave the conversation. Even vegans have carbohydrates, and my good colleague Alexa, an aspiring health and nutrition coach, agrees. Aside from carbs, protein can derive from things such as grains, sprouts, and germs (nutritionally dense and packed full of carbs).
  • Myth #3: Carbs make me fat.

    As previously discussed, the issue is insulin sensitivity, not an isolated issue about mother nature’s fuel source. Training increases insulin sensitivity as well as consistent steady-state cardio and (biomechanics allowing) high-intensity cardio such as jumping rope or sled pushes for intervals.

A Final, and Important, Note

All processed carbs are bad. Have you seen how to make gluten-free cream of rice?

For anyone interested in vegan approaches to eating and carb questions, please follow Alexa Pizzarello on Instagram.

Lift with love, my friends.

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