Monosaccharides (simple sugars) are molecules that usually contain 5-6 carbon atoms. The three most common monosaccharide carbohydrate types include glucose (also called dextrose, fructose (sugar in fruit) and galactose. Glucose is included in the group of those carbohydrates that are the most common or widely seen – disaccharides, sucrose and lactose, and is also the sole structural component of the polysaccharides cellulose, starch and glycogen grouping. Galactose is a common member of the oligosaccharide and polysaccharide group (eg. agar, carrageenan), and is even found in some lipids (glycolipids) located in the brain and in nerve tissues.
Disaccharides are different in their molecular structure as they are composed of 2 simple sugar molecules and are therefore sometimes referred to as “double sugars”. An example would be the disaccharide sucrose, which contains one molecule of glucose and one molecule of fructose. Other disaccharide carbs include lactose (milk sugar) and maltose.
Oligosaccharides are carbohydrates with 3-6 monosaccharide units and are less common. Many oligosaccharides are the result of breaking down polysaccharides. Most naturally occurring oligosaccharides are found in plant foods and include raffinose (a trisaccharide) consisting of melibiose (galactose and glucose) and fructose.
Polysaccharides including cellulose, starch and glycogen, are much larger molecules and comprise up to 10,000 monosaccharides. Most of the stored carbohydrates from nature occur in the form of polysaccharides. For example, glycogen – the stored carbohydrate found in the muscles and liver of humans and many animals – consists of a complex chain of glucose molecules. The two most well-known polysaccharides are cellulose and starch. Cellulose – the basic structural material in plants – contains over 3,000 glucose molecules. We encounter cellulose in the form of insoluble dietary fiber. Starch refers to a class of plant-based poly-saccharides made up of units of glucose. Starches typically comprise a combination of two substances: amylose and amylopectin.
We metabolize starch in our digestive system in stages. First, digestive enzymes called amylases convert the starch into maltose. As the maltose is absorbed through the walls of the intestine it is hydrolyzed to glucose and distributed to cells and muscles for energy or stored as glycogen or fat.
A lot of popular diets used by your clients may try to restrict carbohydrates. In reality, the body needs carbohydrates, especially for PA. What needs to be mastered by the client is 1) understanding the differences between carbohydrate types and 2) the timing of their intake. Cutting carbohydrates is extremely unwise as it is a source of energy, fiber and vitamin C. If this compound is cut from the diet, an entire macronutrient is being cut – and as it happens, this is the macronutrient that is needed in the largest percent by volume.
Dietary guidelines for carbohydrate consumption expressed as a ratio of the total, are pretty standard across the board. The most credible sources put this percent of intake at about 45 to 65 percent of all daily food intake and calories from carbohydrates. The non-active or more sedentary individual would be consuming closer to the 45% mark, while those engaged in PA will have an eating plan that increases the percent up to the 65% level. Therefore, the differences are mainly seen in terms of how active the individual is or if the goal includes overall weight loss or gain.