Avoid simple carbs, but eat intrinsic sugars? No lactose? Blood glucose is crucial, but glycaemic index is not everything? Carbohydrates come with plenty of nuances. Let’s clarify the main concepts.
Straight to the point!
Carbohydrates
“Carbs” and “carbohydrates” mean the same thing. But carbohydrates are not the same as pasta: pasta, rice, potatoes, vegetables and fruit are foods that contain carbohydrates.
Carbohydrates are one of the three main macronutrients, alongside fat and protein. Sources include grains, tubers, pulses, fruit and vegetables. They support body functions and provide fuel for the nervous system and muscles.
Simple carbohydrates
These have small molecular structures. Many provide readily available energy, useful in some sports settings, though digestion and absorption depend on the sugar and food. We distinguish:
- Monosaccharides: “mono” means one and “saccharide” refers to sugar. Examples are glucose (also called dextrose), fructose and galactose. Sucrose is a disaccharide, not a monosaccharide.
- Disaccharides consist of two monosaccharides. Lactose, for example, contains glucose and galactose. Lactase breaks it down so those sugars can be absorbed. Low lactase activity can cause digestive symptoms; if lactose is well tolerated, it need not be avoided.
Complex carbohydrates
These have larger carbohydrate structures. However, molecular size alone does not determine digestion speed: processing, starch structure and the food matrix also matter.
Some foods containing them provide sustained energy and fullness, depending on the meal and portion. Categories include:
- Oligosaccharides: short chains of several monosaccharides, found in various plant foods.
- Polysaccharides: chains of 10 or more monosaccharides, including starch in oats, potatoes and rice.
Sugars
This term usually refers to mono- and disaccharides, such as sucrose in table sugar. Honey contains mainly glucose and fructose, with varying smaller amounts of sucrose.
In everyday speech, people sometimes use “sugars” loosely for all carbohydrates.
Free sugars
These include sugars added to foods and drinks, plus sugars naturally present in honey, syrups, fruit juices and concentrates. Examples include soft drinks, pastries, some sports products and orange juice.
Why limit them in everyday eating? Many sources are easy to consume in large amounts and provide less fullness than whole foods. Glucose can reach the blood readily and stimulate insulin, which helps regulate its uptake. During exercise, readily available carbohydrate can also be useful; context matters.
After a sweet snack, hunger may return quickly. The original article uses 15 minutes as an illustration, not a fixed physiological rule.
Intrinsic sugars
These occur within the intact structure of foods such as whole fruit and vegetables. The surrounding food matrix influences chewing, digestion and fullness.
Why choose these foods? Their fibre, water and structure can slow consumption and change the glucose response compared with juice or sweets. Insulin still responds normally; it does not simply “stay put”. Fibre also supports the gut microbiota and fullness.
Starch
Starch is a complex carbohydrate. The original article estimates it at about 50% of carbohydrate intake, though this varies by diet. Digestible starch is broken down to glucose, which can be used for energy or stored as glycogen.
Glycogen
Glycogen is the storage form of glucose in the liver and muscles. Some absorbed carbohydrate is used immediately and some can replenish these stores. Each gram of stored glycogen is associated with roughly 3 grams of water, so changes in glycogen can change scale weight without equivalent changes in body fat. Keep that in perspective = )
Glucose
Glucose is a simple carbohydrate and an important fuel. It comes from digesting suitable carbohydrates and from glycogen breakdown. During exercise, low glycogen and inadequate incoming fuel can make maintaining intensity difficult and contribute to hitting the wall.
Glycaemic index
Glycaemic index compares the blood-glucose response to a standard amount of available carbohydrate in a food with that of a reference food. It reflects the overall response under test conditions, not simply how fast a food tastes sweet.
It does not describe a whole mixed meal or every individual’s response. Adding wholemeal bread and cashews to chocolate changes fibre, fat, protein and total carbohydrate, which can alter digestion and the glucose response. It also adds energy. Neither chocolate alone nor a mixed snack has one guaranteed response for everyone.
Glycaemic load
Glycaemic load combines a food’s glycaemic index with the amount of available carbohydrate in the portion, divided by one hundred. It is not the same as an individual’s measured glucose response, which also depends on physiology, activity, preparation and the overall meal.
Portion size and meal context matter alongside glycaemic index and load. No single number fully predicts an individual’s response.
A recap of the main concepts
You eat foods containing carbohydrates. Their structure, food matrix, processing and portion influence how they are digested; simple does not invariably mean fast, nor complex invariably slow.
Digestible carbohydrates are broken down into absorbable sugars, including glucose, fructose and galactose. Glucose can be stored as glycogen in the liver and muscles and mobilised later.
Glucose is an important fuel for cycling and brain function, but muscles also use fatty acids and other fuels. Glycogen supplies glucose-derived fuel rather than acting as a completely unrelated substance.
A high glycaemic index can be useful in some exercise contexts. Glycaemic load adds information about the portion, while the whole meal and individual still matter.
You can see how many variables sit behind each question. A sports nutritionist can help explain them and teach you to make choices that personalise your nutrition.
