Carbohydrate foods are an important part of any healthy diet
“Carbohydrate” is a word hot on everyone’s lips at the moment, and not usually in the friendliest sense. In fact, carbohydrates seem to be turning into the next evil scapegoat for everybody’s extra kilos. But the idea that carbs are somehow “bad” for you is unscientific, unwise, and misleading. Carbohydrate foods in their more natural forms are a very important part of a healthy diet. They provide energy, fibre, vitamins, minerals, protein, and water, all of which are crucial for a fit and sound body.
Read this guide to find out more about carbohydrates and the roles they play in the body. Learn how best to incorporate carbs in your diet and find out whether carbs really are fattening.
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What are carbohydrates?
In technical terms a carbohydrate is an organic compound made up of carbon, hydrogen, and oxygen atoms. In food terms we find carbohydrates in many items such as cereals, grains, fruit, legumes, fruit juices, vegetables, milk, sugars, jam, honey, confectionery and soft drinks.
At a rudimentary level, carbohydrates can be described as either simple or complex:
- Simple carbohydrates are the most basic of carbohydrates found in foods such as sugar, honey, jam, confectionery and soft drinks. These contain very little in the way of nutrients other than carbohydrates.
- Complex carbohydrates come from plants, and are found in foods such as grains, breads, cereals, vegetables, legumes and seeds. Unlike simple carbohydrates, these foods contain other essential nutrients, such as vitamins, minerals and dietary fibre.
Technically speaking, however, carbohydrates are classified by the number of single sugar molecules they contain. All carbohydrates are made up of one or more basic sugar molecules binding together to form monosaccharides, disaccharides, and polysaccharides.
Monosaccharides contain one sugar molecule. These are sugars in their most simple form. The most important monosaccharides are glucose, fructose, and galactose.
Also known as dextrose or grape sugar. This is the major form of sugar in the blood and ultimately provides energy for all cells in the body. The body converts the carbohydrates in foods to glucose. It is also present in some foods such as honey.
Also known as fruit sugar or levulose. This is present in fruit and honey and in small amounts in vegetables.
|This is formed during the digestion of milk sugar (lactose).
Disaccharides contain two sugar molecules joined together. The most important disaccharides are sucrose, lactose, and maltose.
This is made up of glucose and fructose. It is found mainly in sugar cane. Small amounts of sucrose are found in some fruits and vegetables such as peaches, apricots, pineapple, peas and sweet corn.
This is made up of glucose and galactose. It is the sugar naturally present in milk.
|This is made up of two glucose molecules, and is found in malt and malted milk.
Polysaccharides can contain up to 10,000 glucose or sugar molecules linked together like a strand of pearls. The most important polysaccharides are starch and glycogen.
This is found in legumes, grains and cereal products such as rice and wheat, and in vegetables, especially root vegetables such as potatoes.
This is a carbohydrate form stored in the liver and muscles; it is like a ‘savings account’ of carbohydrates for the body. Glycogen stored in the liver is used to replenish blood-sugar levels, particularly between meals. Glycogen stored in the muscles is the most readily-available source of glucose used for energy when exercising.
What are carbohydrates for?
Carbohydrates give you energy!
The roles of carbohydrates in the body are numerous and their importance cannot be overstated. Carbohydrates are like building blocks for many of the body’s crucial functions, including:
- Energy! The main function of carbohydrates is to supply the body with energy. Energy is necessary to keep us alive and active in body and mind. Carbohydrates are the most important source of energy for the body. Each gram of carbohydrate gives the body four calories of energy. Carbohydrates need to be supplied regularly and at frequent intervals in order to meet the energy needs of the body. Insufficient stores of carbohydrates in the body results in low blood sugar levels, which can lead to poor concentration and fatigue.
- Protein-sparing effect. One of the most important jobs of carbohydrates is to allow protein to keep to its primary functions such as muscle, hormone, and enzyme building. Protein is considered an “expensive” form of body fuel because it has more important jobs to do than provide energy. However, if there are not enough carbohydrates in the diet, the body is forced to convert protein to glucose in order to supply energy. If this process of “protein burning” continues for too long, the body eventually eats up muscle tissue along with body fat. Muscle helps with metabolism – we use our muscles for exercise and thereby to burn calories. It’s also good to remember that protein is used more efficiently when it's eaten in tandem with carbohydrates. In other words, a sandwich with a lean meat filling is better than just eating lean meat on its own.
- Fat metabolism. Carbohydrates are necessary for fat metabolism. If there are insufficient carbohydrates in the diet, larger amounts of fats than the body is equipped to handle are used for energy. Although the use of fats for energy might sound like a good idea to those who want to lose weight, it results in ketosis. Ketosis disturbs the body’s normal acid-base balance. This can lead to the loss of sodium & fluids, causing dehydration and sodium imbalance. The ketones produced by ketosis are actually toxic substances which can cause headaches, nausea, lightheadedness, bad breath and body odour. Large amounts of ketones can lead to kidney damage; and to coma and death for people with untreated diabetes.
- Brain food. Carbohydrates are the primary and most preferred source of energy for almost all of the brain. Without adequate carbohydrates the body is forced into ketosis to feed the brain. Ketosis is sometimes claimed to help with rapid weight loss, but it has many negative side effects including problems with clarity of brain function.
- The central nervous system. Simple carbohydrates in the form of blood glucose are also the main source of energy for the central nervous system. They alone maintain the correct functioning of the nervous system.
- Red blood cells. Red blood cells can only use glucose and other simple carbohydrate forms for energy. Forms of energy from other nutrients cannot be used by red blood cells.
How many carbohydrates should I eat?
Carbohydrates are the body's main fuel source and should therefore make up the majority of your daily energy intake, mainly in the form of whole grains, vegetables, legumes and some fruit. Exactly how many carbohydrates you need depends on a number of factors, the most important being your daily calorie intake. At CalorieKing, we recommend that about 50 - 60% of your total calories should come from carbohydrates. Variations on this rule are shown in the table below.
Other factors also influence your recommended carbohydrate intake, such as:
- Body weight. More specifically, the amount of body muscle. The greater your muscle mass, the more carbohydrates you need.
- Gender. Males generally require more carbohydrates because of their greater muscle mass.
- Training level. Elite athletes will have greater needs than a recreational athlete who goes to the gym three times a week. The more active you are, the more carbohydrates you will need.
- Type of sport. Endurance-type sports, such as long-distance running, require more carbohydrates than “short-energy burst”’ sports, such as a 100-metre sprint. Any aerobic sport also requires substantial stores of carbohydrates.
- Diabetes. Although most people with diabetes can include a moderate amount of carbohydrates in their diet, individual health will affect particular dietary needs.
- Carbohydrate-sensitivity, grain allergies, digestive disorders. If you have any of these conditions, you may only be able to include a gradual and moderate amount of selective carbohydrates in your diet.
* You should discuss your recommended calorie and carbohydrate intake with your doctor or dietitian.
Daily Total Calories
Daily Total Carbohydrates
Percent of Carbohydrate Calories
From Allan Borushek's Pocket Calorie, Fat & Carbohydrate Counter, 2005 edition.
Are carbohydrates fattening?
There is so much confusion over the issue of whether or not carbohydrates are fattening. Some people say not to eat pasta, bread, or potatoes because they are fattening, but then others say that you should eat more carbohydrates because they are good for you.
The truth is that carbohydrates are an essential part of any diet. However, too much of anything, including carbohydrates, can be fattening. It is best to develop a good understanding of how many carbohydrates you need so as to be sure you don’t eat too many or too few.
Here are some points to keep in mind when considering the relationship between carbohydrates and weight loss:
- No carbs means no real weight loss. When you don’t eat carbohydrates, you break down muscle tissue along with body fat. If you lose weight as a result of this, you also lose your muscle. When you start putting carbohydrates back into your diet, you quickly gain the weight back.
- Food is a complex mixture of many nutrients, so it is impossible to say that just one type of food is fattening. The nutrients which provide energy are carbohydrates, fats, and proteins, and most foods contain all of them. This energy is measured in calories or kilojoules.
|Energy Values Per Gram of Food
As indicated by the chart, different nutrients contribute a different amount of calories. Fats provide over twice as many calories as carbohydrates.
- We usually eat carbohydrates and fat together. For example, a Spaghetti Bolognese meal has a sauce made with oil and minced meat that is topped with cheese. These ingredients contain a lot of fat, and therefore contribute many calories. Pasta alone contains very little fat and is made up mainly of carbohydrates, which contribute fewer calories. This pasta meal is fattening more because of the sauce than the pasta.
- Too much of anything is fattening! If you eat too much of anything, it’s going to add excess weight. As a recent World Health Organisation report points out: "It is important to state that excess energy (calories) in any form will promote body fat accumulation and that excess consumption of low-fat foods, while not as obesity-producing as excess consumption of high-fat foods, will lead to obesity if energy expenditure (exercise) is not increased." When more carbohydrates are eaten than is good for the body, most of them are stored in the liver and muscles as glycogen; the remainder is stored as fat.
- Carbohydrates are more filling than fat. The fibre content of most carbohydrates swells in the digestive system, which makes us feel full faster than other foods do. Also, the conversion of dietary fat to body fat requires very little energy compared to carbohydrate conversion; in fact, only 3% of energy intake is required in this process. Compared to carbohydrates, it can be easy to eat too much fat because foods high in fat are generally low in dietary fibre; therefore it takes more of those foods for us to feel full.
Which carbohydrates are better for me?
When considering which carbohydrate foods to include in your diet, it's best to think in terms of refined and unrefined carbs.
Those from the unrefined group make better choices. Unrefined carbohydrates provide your body with energy for a longer period of time. They also keep your blood sugar levels even and provide fibre for your digestive system. Foods high in fibre fill you up quickly and are generally harder to overeat.
Good sources of unrefined carbohydrates include whole-grain bread, brown rice, beans, vegetables, nuts, and seeds.
Refined carbohydrates provide short bursts of energy to your body. They may cause your blood sugar levels to spike and then drop, leaving you feeling hungry again a short time after eating. It can be easy to eat too many refined carbohydrates.
Examples of refined carbohydrate foods include lollies, biscuits, and soft drinks.
So don't cut carbohydrates from your diet, but do choose wisely and stick to unrefined carbohydrates whenever possible. And as with all foods, watch your portion size!
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This article was compiled in consultation with CalorieKing.com.au experts and in reference to the following sources:
World Health Organization, ‘Carbohydrates in Human Nutrition – Interim Report of a joint FAO/WHO Expert Consultation,’ 1997
Last updated: November 2nd, 2006