Carbs: The Basics

“Carbs” have gotten a bad reputation.  With the popularity of low carbohydrate, high fat diets, many feel that carbohydrates are what is holding you back from reaching your body or performance goals.  Many athletes and celebrities have claimed their remarkable performance and bodies on a low carbohydrate diets, but is it right for you?  First, let’s take a look at the basics behind carbohydrates and their function and need during exercise and sport.  

Why You Need Carbs for Training and Exercise

Carbohydrates play an important role during exercise and sport and is the primary fuel source during most activities.  Whether you are going for run, hitting a HIIT class, strength training or sport conditioning, your body is primarily using carbohydrates to fuel your training.   The most utilized form of fuel for our muscles to contract (or move) are carbohydrates in the stored form known as muscle glycogen.  When muscle glycogen runs out, our liver, which also stores glycogen (carbs), helps supply the muscle.  

The brain and central nervous system also rely on carbohydrates during sport and exercise to function optimally.  Low carbohydrate availability, likely from inadequate consumption, can impair performance by impairing concentration, coordination, pacing, fatigue and motor skills.  Not only can this lead to impaired performance, but it can result in injury.       

So, How Much Do I Need?

What you need depends on the frequency, intensity, time and type of training and exercise you engage in.  Therefore individual carbohydrate needs, especially for athletes and physically active individuals, are on a case by case basis.  An endurance trained individual who runs 3 or more times per week will have a higher carbohydrate need than an individual who strength trains 3 or more times per week.  Strength trainers and power athletes also need a significant amount of carbohydrates to train effectively.       

The goal is to consume enough carbohydrates to fuel your training sessions and sustain. A simple method to determine your carbohydrate needs would be to consume 45-50% calories from carbohydrates.  For athletes and active individuals, determining your carbohydrate needs on a gram per kilogram of body weight basis is more appropriate for proper fueling.  The following recommendations from Burke et al (2011), have been accepted as a guide for athletes:

Light Low intensity, skill based 3-5 g/kg body mass
Moderate Moderate exercise (~1 hour per day) 5-7 g/kg body mass
High Endurance exercise (1-3 hours/day moderate or high intensity exercise) 6-10 g/kg body mass


For example, a 145 pound adult (~66 kg) engaging in moderate intensity running would need a minimum of 330 grams of carbohydrates.  She can vary her carbohydrates day to day depending on her training load to be higher on more intense days.  Carbohydrate needs can generally be met through regular meals of high carbohydrate foods.  These include rice, bread, potatoes, and pasta.  Pre and post workout carbohydrates may be needed during days where you are unable to meet your needs during regular meals.

For active individuals with lower activity level than athletes may have lower calorie and overall carbohydrate needs.  If weight loss is a goal, it is still important to ensure you have enough carbohydrates to fuel your activities.  Cutting carbohydrates can be counter-intuitive to reaching your training and body composition goals.  

My Personal Experience with Carbs…

I’ve experimented with lower carbohydrate and higher carbohydrate diets to support my exercise.  When I increased my carbohydrate intake from to support my training, I was not only able to train harder, my body composition improved as well.  I did not restrict calories, simply changed my ratio of carbohydrates, fats and protein.   


Burke, Louise M., et al. “Carbohydrates for training and competition.” Journal of Sports Sciences, vol. 29, no. sup1, 2011, doi:10.1080/02640414.2011.585473.

2 thoughts on “Carbs: The Basics

  1. so how can you figure out what your ratio of carbohydrates, fats and protein should be?
    i recently joined a 6 week program at a cross fit gym where the goal is to lose 20lbs in 6 weeks and they have me on a meal plan that is very high in protein, very low in carbs, and low in fats. I eat about 42-54 grams of protein per meal, plus 2 whey protein shakes in between meals, roughly 14-22 grams of carbs (with breakfast and lunch only) and dinner is the only meal that allows a little bit of fat but no carbs. Also i cant have any sugar and i feel like I’m having withdrawals lol… what are your thoughts on this diet?

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