At its simplest form, a carbohydrate is a biological molecule that contains a carbon, a hydrogen and an oxygen atom. However, in biochemistry we use carbohydrate to represent saccharides – a group that includes sugars, starches, and cellulose. Saccharides can be classified in three different ways:
- Monosaccharides – “mono” represents one, leaving us with “one sugar”
- Oligosaccharides contain a small number (usually 2-10) simple sugars linked together. (glucose + glucose = Maltose)
- Polysaccharides – “poly” represents many, leaving us with “many sugars.” These long chains of monosaccharide units can come straight or highly branched.
It is important to remember that while carbohydrates, at 4kcal/g, are a significant source of energy in most diets, they are NOT an essential nutrient. This is to say that we do not need them to survive. However, it is important to note that in relation to fiber, inadequate intake has been linked to increased mortality.
Over the years, carbohydrates have been classified as “simple” or “complex.” While this is meant to distinguish sugars (monosaccharides) from polysaccharides, it has only created even more confusion in the nutrition space. The truth is that neither term serves justice to the nutritional quality of any food. These terms do not address micronutrient content, or even blood sugar effect of the given food.
The glycemic index was also developed to help classify carbohydrates. This is a measure of how quickly a food can raise our blood sugar. The higher the glycemic index of a food, the faster the increase we see in blood sugar. Obviously foods like sugar, candy, and cereals will have a higher glycemic index whereas higher-fiber foods like vegetables and whole grains will have a lower glycemic index.
The reason this matters is in relation to insulin – our storage hormone. When blood glucose quickly shoots up, it usually triggers a release in insulin (usually equal to the amount of glucose present.) High levels of insulin can lead to high levels of fat storage.
Unfortunately, the glycemic index is flawed (to put it mildly.) First, it does not take into account food pairing. While you may eat a chocolate bar as a dessert by itself, chances are that you won’t have many clients that sit down to a bowl of rice or piece of bread by itself. Food pairings will change the blood glucose response, hence defeating the “glycemic index.”
Other factors such as type of sugar and time of day of consumption (pre/post workout) leave the use of the glycemic index with a lot to be desired.
The glycemic load was created as a response to the issues with the glycemic index, but is still a flawed methodology as it does not take into account the constituents of the carbohydrates (fiber, micros, etc..)
Most recently, the insulin index has been used, which represents the amount of insulin the body produces in response to a particular food.
It is our belief that this method will continue to evolve, but is still not yet perfect.
While virtually all carbs (high GI, low GI, etc.) end up as glucose in the body, it is important to make a note about dietary fiber.
Fiber is indigestible, and comes in two forms: soluble and insoluble.
Soluble fibers attract water and turn to gel during digestion. Found in oats, nuts, seeds and some fruits and veggies. Because soluble fiber can help decrease cholesterol levels, it may help lower heart disease.
Insoluble fiber is found in foods like wheat bran, root vegetables, and fruit and vegetable skins. These fibers help us feel more full, keep things moving in the GI, and boost our overall gut health.
Carbohydrate Intake Recommendations
To start, the dietary guidelines set forth for us have carbohydrate prescription at 45-65% of total caloric intake.
Remember, these are the same guidelines that had protein intake as low as 10- 15%, and did not take into account that your clientele is likely resistance training with performance and/or aesthetic goals.
The truth, as always in nutrition, is that there is no “optimal range” for carbohydrate prescription.
However, carbohydrates are the final macronutrient discussed in this text for a reason. If calorie, protein, and fat prescription are done correctly, carb prescription takes care of itself. This will ensure that you have accounted for:
- Client’s physical stature (height/weight/etc)
- Activity level
- Training goals
- Training modality
- Training age
- (finish this list with considerations from protein and fat)
A final note: Despite what the media has said, carbs are neither “good” nor “bad”, remember they are a non-essential nutrient – we technically don’t even “need” them. That said, they can play an important role in several of the issues you will see as a nutrition coach – socially, physically, hormonally, and otherwise.