What carbohydrates are and why they are important

By Mike Lackner

“Carbohydrates!” There, I said it, the word that seems to be taboo these days. For some reason, carbohydrates have become the outlaw of the nutrition world. The new obsession with almost every diet and food product on the market is to eliminate carbs. Dieticians and self-proclaimed gurus are misinforming the general public about the dangers of carbohydrate consumption. They preach elimination of carbohydrates, instead of discipline and knowledge of them. Some even prescribe the addition of fats as a replacement for carbs. If you recall…last month’s article explained why carbohydrates are important and the dangers of eliminating them from your diet. This article will go into further depth to explain what carbohydrates are and why they are an important part of a healthy nutritional programme.
What exactly is a carbohydrate? Good thing you asked. The name “carbohydrate” clues us in that carbohydrates are made up of carbon, hydrogen and oxygen molecules. They are the product of the photosynthesis process by which plants turn sunlight into food. That is why plant foods are the best and most abundant source of carbohydrates.

Carbohydrates come in two categories: Simple (sugars such as monosaccharides and disaccharides) and Complex (polysaccharides).
Simple sugars are composed of a single unit. Glucose (grape sugar), galactose, and fructose (fruit sugar) are the most common and recognizable of the monosaccharides family. Disaccharides are sugars made up of two simple (monosaccharides) joined molecularly. Sucrose, which is cane sugar, is the obvious popular member in this group. It is composed of a sucrose and fructose molecule joined together and is used in millions of products. Sucrose is better known as table sugar. After it is consumed, the body breaks it down back into fructose and sucrose. Lactose (milk sugar) consists of glucose and galactose. There are also alcohol sugars, such as sorbitol, which is the alcohol form of glucose. However, the liver turns sorbitol into fructose during digestion.
Fructose is a little more ‘dangerous’ than other sugars, because it does not need insulin to process it as much as other dietary sugars do. At the same time, in the gut cell layer, there is something called the "disaccharide effect" where fructose gets more quickly converted to fat (triglyceride) than other sugars. Therefore, fructose moves more easily into your fat stores than other types of sugars. Most other simple sugars are more likely to be used as energy first, only an overabundance is converted to fat.
Complex carbohydrates (polysaccharides) are basically a long chain of glucose molecules hooked together. They are found mainly in plants such as rice, potatoes, beans and green vegetables. During digestion, these long chains are broken apart into the base glucose molecules. However, it takes longer to break these chains apart and then break down the resulting simple sugar glucose than it does to simply absorb a simple sugar like glucose or fructose. Our systems break down fructose much faster than sucrose.
The above paragraph is very important when trying to understand why not all carbohydrates are bad. Carbohydrates raise blood sugar levels, and this is associated with making the body work harder to produce more and more insulin to deal with the blood sugar produced. It’s not advisable to have high insulin levels. Due to your body’s inability to use more than small amounts of glucose at a time, it’s more likely to store glucose as fat when insulin levels rise rapidly. However, you do not need to reduce carbohydrates to very low levels to lose weight or improve insulin resistance. The key is to choose your carbohydrates in a way that keeps your blood sugar level and insulin steady. A measurement used to determine which carbohydrates to choose is the Glycemic Index.
All carbohydrates turn into glucose in your system, just at different rates. It was thought that “simple” carbohydrates, made of “simple” sugars (such as sucrose found in cool drink, table sugar, cakes, cookies, fruit, etc.) were less desirable than “complex” carbohydrates – foods containing starch (such as potatoes, rice, beans, flour and vegetables). People with diabetes were told to avoid sugar because of the way it raised their blood sugar level. However, experts now believe that how quickly the carbohydrate is absorbed (which the Glycemic Index tells you) is more important, not just how “simple” or “complex” the carbohydrate is.
Plants turn sugar into starches, it’s how they store energy. So, when you eat foods such as potatoes, turnips, squash and beans, you get carbohydrates in the form of starch. Our bodies turn starchy foods into glucose, to be used for fuel. The same process occurs for foods containing simple sugars. So, as I stated before…all sugars are converted to glucose for fuel. Our body stores some carbohydrate in the form of glycogen in the liver and muscles to be used as a short-term source of energy, but most glucose is used as immediate fuel.
It had been assumed that foods in the complex carbohydrate category, such as starchy vegetables and whole grains, were all absorbed more slowly than “simple” sugar foods. However, the glycemic index has shed light on how these carbohydrates are absorbed and how they affect blood sugar. It turns out that some foods made from simple sugars actually raise blood sugar more slowly than some “complex” carbohydrates. The glycemic index is one way to categorize foods by how rapidly they increase blood glucose levels, causing insulin to be released by the pancreas. This can be a useful tool in evaluating foods, especially for people with insulin resistance.
The higher a food on the glycemic index, the more quickly blood sugar elevates after eating it. A glycemic index of 55 is considered to be “low.” A “high” glycemic index would be 70 or above. This rating is derived upon glucose being given an arbitrary value of 100. Low glycemic index foods are considered healthier because their energy is released in a slow and sustained way. High glycemic index foods encourage a quick release of glucose and insulin that stresses the body. This quick release, called a spike, can cause low energy, food cravings, hypoglycaemia, elevated cholesterol levels, hormonal imbalance, kidney stones and high blood pressure.
Glycemic Indexes were determined in the following way. Volunteers ate 50g of carbohydrate from a specific food and their blood sugar was measured every 15 minutes for two hours afterwards. The results were then compared to their response upon taking 50g of glucose given as food. This test was repeated to get an average response and results assimilated for 8-10 other people. The final product was the glycemic index allocated to that food.
Like many scientific ‘rules’, the glycemic index has a couple of ‘flaws’ to watch out for. Though it provides some very useful information, it should not be the only measure of the value of a food. For example, a can of Coca-Cola has a glycemic index of 63 and five dried dates rate 103, but it should be obvious that Coca-Cola is not a preferable carbohydrate source to dates.Factors that influence how quickly blood sugar is raised by a food include its chemical composition, how long the food is cooked (to break down the carbohydrate molecules, making them more quickly absorbed) and what other foods are eaten with the food. For example, bread by itself might be quickly absorbed, but bread with margarine takes longer to break down because of the presence of fat. If you eat a food that has a high glycemic index at the same time as some fat or protein, it changes how the food is absorbed and reduces the importance of the glycemic index. Foods are not typically eaten by themselves, but along with other foods, which affects how quickly that food is digested. When you eat high glycemic foods with low glycemic foods you can average the effect. In some cases, the glycemic index of a food is based upon improbable amounts of the foods (that a person would not usually eat in one sitting). To get 55g of carbohydrate from bread, it takes about 3½ average slices. On the other hand, to get 55g of carbohydrate from carrots takes about 3 cups!
The glycemic index helps us understand how specific carbohydrates affect blood sugar levels. It can be very helpful, but should not be used exclusively to determine your diet. A healthy diet, for weight loss, weight maintenance, or weight gain, includes a variety of quality carbohydrates. A good way to know how a carbohydrate affects your blood sugar levels is to test your blood sugar after eating the food, following the instructions of your physician or diabetes educator. This may seem a little unrealistic, but most top athletes I know have done this, as well as testing their own ketones to evaluate their body’s response to their diet. If you are really serious about your body you’ll take a couple of extra minutes after spending all that time in the gym and planning all your meals around it.
The glycemic index helps us understand that it is not carbohydrates that are bad, but how we choose to consume them. If we consistently choose foods that are high on the glycemic index, we will have high blood sugar levels and be more susceptible to gaining fat and having cravings. If we choose low glycemic carbohydrates, they will burn slowly in our system and not elevate our insulin levels rapidly, making us store more fat. We will also have steady blood sugar levels, which impedes sweet cravings. Keeping your cravings in check is very important because it prevents you eating more than you should. When you eat too many carbohydrate calories the excess, unneeded for fuel, is converted to fat. This is no different to food in general - too much food equals too many calories and results in fat storage.
Now that you understand how carbohydrates are made and the differences between them, we can discuss their role in our bodies. As stated earlier, carbohydrates are broken down in the small intestine into a simple sugar known as glucose. Glucose is absorbed in our blood stream and stored in the muscle as glycogen, which the muscles use for fuel. Once again, the muscles use GLYCOGEN - a broken down CARBOHYDRATE - for fuel. The muscles store glycogen until it is needed (anabolism). The trained muscle increases its ability to store glycogen, and since glycogen is bound together with water (2.7g of water for 1g of glycogen), this extra bulk in the muscles causes them to swell and look bigger. Not only will your muscles have more available energy, they will be as packed full of glycogen as possible, maximising your apparent size!
Carbohydrates not only fuel your muscles, they are the main source of fuel for your brain, which controls all of your functions. An inadequate carbohydrate intake may cause your body to dehydrate, especially if you work out.
In an indirect way, a carbohydrate deficiency can make you lose muscle. Protein is the building block for hormones, enzymes and blood cells. Protein also helps build and repair body tissues, including muscle, and maintain a healthy immune system. However, protein is not critical for fuelling working muscles. When facing an insufficient carbohydrate supply your body seeks to use protein as a fuel. This diverts your protein from its more important (and biologically correct) roles. So remember, restricting your carbs forces your body to use protein when carbs should be used, sacrificing potential muscle gains.
People who preach that carbohydrates are bad and should be avoided are speaking recklessly. They play on people’s lack of knowledge, fooling them into following their beliefs or buying their products. Sure, some carbohydrates are not good to eat and having too many will cause them to be converted to fat. With a proper knowledge of carbohydrate types and how they are used by your system, it is easy to make correct decisions about how to consume your necessary carbs.
Carbohydrates will not make you fat - eating the wrong kind and eating too many will make you fat. Do not put your health and athletic performance at risk - eat suitable carbohydrates sources in appropriate quantities. Doing so will ensure optimal performance, optimal results and optimal health.