What are carbohydrates?

Carbohydrates are important macronutrients for your health. They provide the main source of energy (calories) for the body, especially your brain and muscles during exercise. Your muscles and liver store carbohydrates in the form of glycogen. During exercise, glycogen is broken down to sugar (glucose) and used for energy by your muscles. Your liver releases glucose to maintain stable blood glucose levels. Low glycogen stores can make you feel tired and cause training, exercise and playing sports extremely difficult. Consuming enough carbohydrates helps you have enough glycogen stores.

There are 3 major types of carbohydrates found in food: sugar, starch, and fibre.

Sugar is a simple carbohydrate and provides a quick source of energy for your body. Sugar is found naturally in some foods and is added to others. Foods such as fruit, milk, honey, and maple syrup all naturally contain sugar, whereas foods such as breakfast cereals, jams, flavoured yogurts and baked foods contain added sugar.

Starch is a complex carbohydrate that originates from plants. They provide a slower release of energy to your body compared to sugars. Foods such as whole grains, legumes and starchy vegetables contain starches.

Fibre is found in plant-based foods and does not provide energy because it is not absorbed by your body. Fibre can help to lower blood cholesterol, control blood glucose levels and keep your bowels regular. Food such as vegetables and fruit, whole grains, and legumes contain fibre.1,3

How much carbohydrate do I need?

For males and females of all ages, Health Canada recommends a minimum of 130 g/day of carbohydrates, with most of this carbohydrate being used to fuel the brain.

Carbohydrates should contribute 45-65% of your total daily energy intake to help meet your energy and nutrient needs.2

How many carbohydrates should I consume to optimize my performance during exercise and training?

Before Exercise

Include carbohydrates in your pre-workout meals/snacks. Eat a small meal or snack 1-4 hours before you exercise to prevent feeling too hungry or too full. This will help keep your blood glucose levels stable and provide energy during exercise. Aim for lower fiber choice, as they are easier to digest.

During Exercise

During intense or prolonged exercise, aim for 30-60 grams of carbohydrates per hour. This is helpful during marathons, long cycling rides, and soccer or hockey games. Aim for lower fiber and easily digested carbohydrate-rich foods if you need to eat while exercising to prevent an upset stomach, bloating and cramping.

Try pretzels, crackers, bananas, sports drinks and gels.

After Exercise

Eat a carbohydrate-rich meal or snack after intense exercise lasting more than an hour. This will aid in replenishing your glycogen stores for the next time you exercise. Dietitians of Canada recommends eating this meal or snack within the first 30 minutes after physical activity.

However, a carbohydrate-rich recovery meal/snack is not needed if you exercise less often or after lighter activities such as walking or yoga.3

What is carbohydrate loading?

Carbohydrate loading is a strategy used by competitive and elite athletes to maximize muscle glycogen stores before long, intense exercise training or competitive events such as marathons, distance cycling, triathlons or soccer tournaments. It can be helpful when training lasts longer than 90 minutes and when it is hard to eat during exercise. Carbohydrate loading may be help you perform better and train longer than normal.

If you want to try carbohydrate loading, Dietitians of Canada recommends 8-11 grams of carbohydrate per kg of body weight per day for 1-3 days before your competition or training session. Carbohydrate loading is often accompanied by short-term weight gain due to water that is store along with the glycogen – this is normal and short-term.3

Do I need to eat a low carbohydrate diet if I want to lose weight?

Carbohydrate restricted diets are usually calorie restricted as well, which may help with weight loss in the short-term because you are eating fewer calories altogether. Dietitians of Canada reports that the long-term health effects of low carbohydrate diets are not known. When you follow a low carbohydrate diet, you may miss out on the health benefits of legumes, vegetables, fruit, and whole grains, which provide vitamins, minerals, dietary fibre, antioxidants and help to prevent chronic diseases such as type 2 diabetes, heart disease and bowel cancer.1

A reduction in energy (and carbohydrate) intake of approximately 500-900 calories per day can result in a significant drop in micronutrient intake and could increase the risk of micronutrient inadequacy. Evidence suggests that the greater decrease in carbohydrate intake, the greater decrease in fibre intake.4


  1. Dietitians of Canada. (2018, April 24). Carbohydrates, Health and Weight Loss. Retrieved from https://www-pennutrition-com.subzero.lib.uoguelph.ca/viewhandout.aspx?Portal=UbY=&id=J8PoUA0=&PreviewHandout=bA==
  2. Health Canada. (2006, June 29). Dietary Reference Intakes. Retrieved from https://www.canada.ca/en/health-canada/services/food-nutrition/healthy-eating/dietary-reference-intakes/tables/reference-values-macronutrients-dietary-reference-intakes-tables-2005.html
  3. Dietitians of Canada. (2018, January 24). Carbohydrates in Sports Nutrition. Retrieved from https://www-pennutrition-com.subzero.lib.uoguelph.ca/viewhandout.aspx?Portal=UbY=&id=J8HrXwU=&PreviewHandout=bA==
  4. Diet Composition – Low Carbohydrate. (2019, January 17). Retrieved from https://www-pennutrition-com.subzero.lib.uoguelph.ca/KnowledgePathway.aspx?kpid=25612&trid=25973&trcatid=42

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