What is a carbohydrate?

The simplest form of carbohydrate is what is known as a single sugar molecule called glucose. To be utilized as energy in every cell in the body, all carbohydrates eventually end up as glucose. As we know, man has also done a good job of isolating glucose and adding it to many packaged foods. Chemically, glucose is known as a monosaccharide (mono= one, saccharide = sweet). If two glucose molecules are joined together it is called a di-saccharide. Common table sugar is a di-saccharide called sucrose.

Other common di-saccharide are maltose and lactose. Just to confuse you, fructose (the common sugar in fruit) is a slightly different single sugar molecule than glucose. All carbohydrates are simply chains of the glucose molecule linked together (polysaccharides). In food, these polysaccharides are called starches. In muscle, these stored polysaccharides are called glycogen. Dietary fibers are complex structures that contain many different sorts of sugar molecules, but they are different to starches and sugars. They cannot be digested. Humans do not possess the digestive enzymes that break apart the bonds that hold these sugar molecules together. Therefore, they pass though the system undigested.

What's wrong with today's carbohydrates?

We are the product of industrialization. Inventions ranging from Jethro Tull's seed drill (in 1709) to the high speed steel roller mills for milling cereals (19thcentury) are all advances in food processing to give food a longer shelf life (6). Although foods are based on our staple cereals such as wheat, oats, corn and rice, the original grain has been ground down to produce a powder-like flour, minuscule in particle size.Food chemists know that the finer (smaller) the particle size flour, the more fluffy and delicious the food will be(7). It also extends shelf-life of the end product enormously. However, the constant refinement of the whole-food over recent centuries has resulted in dire consequences to our health that we are only now just becoming aware of. The incidence of obesity, diabetes and cardiovascular disease are at all time, record-highs in human history. This is directly linked to over-consumption of refined foods. Highly refined foods create poor insulin management. They are too rapidly absorbed and flood the blood stream with sugar (glucose). The pancreas secretes insulin into the blood in an attempt to eliminate this flood of glucose.

Over a gradual period of time cells become resistant to this constant bombardment of high insulin that refined foods induce. These high insulin levels desensitize our cells (particularly in muscle) and the pancreas has to work harder to secret more and more insulin, all to complete the job of nutrient transport into cells. After years of this physiological abuse, the pancreas gives up and fails to produce much insulin at all. When this occurs, doctors politely term the condition “adult-onset diabetes.”

While some poor folk are genetically predisposed to developing this condition, adult-onset diabetes, in most cases, is completely preventable. In fact, developing adult-onset diabetes, in most cases, is more like a trophy that says “congratulations, through years of dietary abuse, you have successfully managed to wear out your pancreas.” Some trophy huh? It's one disease that has fatal implications to health and once you have it, you carry it for the rest of your days. Which, by the way, are usually reduced in number.

How do carbohydrates work?

Remember, glucose is the usable form of carbohydrate. All carbohydrates (sugars and starches) must be broken down to glucose. This process is called digestion. Monosaccharides (fructose, glucose, galactose) are absorbed rapidly from the small intestine into the blood stream where they travel to be used as a source of energy by cells. All other carbohydrates (polysaccharides) have to be cleaved apart by digestion in the small intestine.

We used to think of carbohydrates as two different forms, simple and complex. However, this tells us little about how different carbohydrates behave in the body(8). It was widely believed that complex carbohydrates such as rice or potatoes were slowly digested and all simple carbohydrates (sugars) were absorbed rapidly. However, scientific research examining real human digestion demonstrates that these assumptions are wrong(6).As bodybuilders and athletes, we need to forget the words simple and complex when talking about carbohydrates. We need to think in terms of low Glycemic Index and high Glycemic Index carbohydrates.

What is Glycemic Index?

Because of the profound impact on our health, scientists have started to investigate the physiological response of different foods on blood sugar levels. The glycemic index (GI) of food is a ranking of foods based on their immediate effect on blood glucose (blood sugar) levels.The GI ranks a food on a scale from 0 to 100 according to the extent to which it raises blood sugar levels after eating. Carbohydrate foods that break down quickly during digestion have the highest glycemic index rating. Their blood sugar response is fast and high. The substance which produces the greatest rise in blood sugar is pure glucose. Therefore, the GI of glucose is 100. Every other food is ranked between 100 and zero. Carbohydrates that break down slowly, releasing glucose gradually into the blood stream, have a low glycemic index(6). Foods with a high GI produce a great surge of glucose into the blood steam. This surge in blood glucose is matched by another in insulin in an attempt to control blood glucose levels. High GI foods produce marked fluctuations in blood glucose levels. Low-GI foods, by virtue of their slow digestion and absorption, produce gradual rises in blood glucose and insulin levels, and have proven benefits for health.

Why is the GI factor so important?

Quite simply, by selecting foods with the GI factor in mind, you will decrease the amount of insulin secreted and promote insulin sensitivity within tissues. This adds up to making insulin more effective within your body. The GI concept was first developed in 1981 by Dr. David Jenkins (a professor of nutrition at the University of Toronto, Canada) for diabetics as an aid to food selection to help insulin management. This initial work has been expanded tremendously by scientists of the University of NSW, Sydney Australia.

The GI factor is now a well renown nutritional strategy to help prevent and control type 2 diabetes, heart disease, and obesity (6). For the drug-free bodybuilder, knowledge of the GI index of carbohydrate foods is invaluable. It allows you to control and manipulate natural insulin secretion to obtain the maximum anabolic effect from your training.

Manipulating insulin levels in the hours after intense training will facilitate maximum nutrient transportation into muscles, accelerating recovery and cellular adaptation.

One of the hardest parts of fat loss for definition is feeling hungry all the time. This gnawing feeling is not necessary to lose fat. Low GI foods are natural appetite suppressants. Controlling insulin by using the GI factor of foods ensures fat is burned and the anabolic drive is maintained all day, every day.

It's all in the digestion.

What makes one carbohydrate different to another in terms of its GI rating?

This all has to do with the physical state of the carbohydrate in the food. When carbohydrates are consumed in their natural packaging, such as whole or intact grains, oats, barley, whole wheat and vegetables, the food will take longer to digest (break down) and its monosaccharides will enter the blood stream slowly. These foods will have a lower GI factor. Therefore the whole grain or unprocessed food will always have more gradual, prolonged effect on blood sugar. (There are some exceptions to this, such as potatoes and different forms of white rice.)The other aspect that governs digestion of a carbohydrate is the ratio of two different types of starches the food has. These two starches are called amylose and amylopectin. To put it simply, amylopectin molecules are larger, more open and easier to digest. Thus, foods that have little amylose and plenty of amylopectin within their carbohydrate will be more rapidly digested and absorbed into the blood stream and will possess a higher GI number. Some examples of high amylopectin to amylose carbohydrate foods are wheat flour and Calrose white rice. These foods have high GI numbers. Some foods that have more amylose than amylopectin are basmati white rice, durum wheat pastas and all sorts of legumes. Therefore, these carbs possess low GI numbers.