Carbohydrates are often associated with slow digestive processes and weight gain, but they are also an essential and healthy part of our diet. Finding out what they really are and which of the two main types are best, will give you useful tools for maintaining a healthy diet and stable weight.

Carbohydrates are part of the chemical make-up of our body, consisting of carbon, hydrogen and oxygen. The body uses carbohydrates as a fundamental energy source which is more easily converted into glucose than fats or proteins. Glucose, a form of sugar, is moved by the blood all around the body to where it is needed, and it can also be stored in the muscles and the liver. The hormone insulin is released by the pancreas to control the glucose uptake of the body's cells. Excess glucose becomes glycogen, and this gets stored in the liver or as fat. When the body needs energy, glycogen can be converted into glucose which can then be used readily by the cells.

Often portrayed as bad for dieters, the amounts of carbohydrates are sometimes reduced drastically in 'low-carb' diets in order to promote weight loss. In actual fact, protein has slightly more calories, and fat has more than twice as many as carbohydrates do. We need them for our daily health and energy requirements, and while it is true that eating a very high carbohydrate diet could lead to extra stores of sugar and fat in the body, it is also true that eating too much or too little of any of the food groups has negative effects. The key is to understand the types of carbohydrates and the reasons for including them in your meals.

Carbohydrates are usually grouped into the categories of either complex or simple carbohydrates.

Complex carbohydrates

This group is otherwise known as starch. Examples of starchy foods are brown rice, lentils, chickpeas, nuts, beans, oats, bananas, potatoes and root vegetables, and grain products like brown bread, pasta, cereal and some flours.

Simple carbohydrates

Simple carbohydrates are known as sugars. Natural sugars are found in fruits and vegetables. Processed or more refined sugars are often contained in biscuits and cakes, sugary drinks and soda, confectionery, jelly, jam and honey.

Are simple or complex carbohydrates the best?

Generally complex carbohydrates are the healthier and most useful choice, especially foods that have not been processed too much. They include the vital fibre, minerals, vitamins and nutrients that your body needs. Fibre does not convert to sugar, so it assists the digestive and elimination processes by passing through the body. There are two types of fibre -- insoluble and soluble. Insoluble fibre is not able to be dissolved in water, and its function is to push food through the intestinal tract, to assist with regularity, and reduce the risk of constipation. Soluble fibre is water soluble, and its job is to bind to fat and take it through the intestines and out of the body. This type of fibre fills you up for longer, stretching out the time between feelings of hunger and the instinct to snack.

Another benefit of complex carbohydrates is their slow metabolism of glucose. This results in a more stable energy level which lasts longer. Simple carbohydrates are quicker to release glucose, especially if the sugars are more refined. While this is sometimes an advantage for a quick energy burst, blood sugar levels can spike and drop and be more unreliable as a result. The energy is not long-lasting, so hunger occurs again more quickly and the body asks for more food. Excessive consumption of simple carbohydrates is also associated with diabetes and cardiac disease, so moderation is necessary.

There are fewer nutritional benefits with simple carbohydrates, and although they are easily digested they often contain more sugar than the body needs, which can of course be stored as fat. For instance, white bread is highly processed and contains only a small amount of energy and fibre. Brown or wholegrain bread provides more energy which is also longer-lasting, as well as having the advantages of extra fibre.

Understanding carbohydrates is an important step towards maintaining a good diet, whether you are trying to lose weight or stay healthy. Using the right carbohydrates wisely can provide you with the energy you need each day, so that you can live life to the full and enjoy your health.