What are carbohydrates?
Carbohydrate can be found in most foods and is in the form of simple sugars, starches and fibre. Most natural whole foods that we eat contain good quality carbohydrate such as whole grains, vegetables, fruit and legumes (peas, beans, lentils). Other starchy foods such as white rice and white bread contain carbohydrates but these foods are highly processed and so they contain less fibre and vitamins and minerals compared to whole grains (wholegrain rice, brown rice, wholemeal bread). Other foods contain carbohydrates such as sweets, cakes, biscuits etc. but mainly in the form of sugar.
Why are carbohydrates important?
Carbohydrates are broken down in the body into the sugar glucose which is used for energy. Carbohydrate provides the main source of energy for our bodies and is an essential source of energy for the brain and central nervous system. Fibre is also important for digestive health and protects against diseases such as heart disease and cancers. Low-carbohydrate diets can result in constipation, nausea, headache and halitosis. Low carbohydrate diets in the long term can lead to low blood sugar levels, and low intakes of vital nutrients such as B-vitamins, iron and fibre etc.
How much carbohydrate should we have?
Carbohydrate intakes are very individual, and for an active person this can be based on amount in grams per kilogram of body weight depending on activity levels. For example, you may need less on less active days and more on more active or heavy training days.
Which kind of carbohydrates should we eat?
We should try to have starchy carbohydrates as the main bulk of our carbohydrate intake (e.g. rice, couscous, potatoes etc.). Try to have wholegrain versions such as wholegrain rice or wholemeal bread as they contain more nutrients and fibre and can be more filling. We should also include lots of vegetables in the diet and a good amount of fruit.
What about sugar?
Sugar is a type of carbohydrate and is found naturally in some foods such as fruit (fructose) or milk and milk products (lactose) or sugar can be added like the added sugar found in sweets, biscuits, fizzy drinks, sugary breakfast cereals etc. Foods that contain sugar naturally also contain lots of other healthy nutrients too and so they are much better for us. For example most fruit is low in calories, contains vitamins and mineral, antioxidants and fibre. Milk contains vitamins and minerals and protein. Sweets, fizzy drinks, biscuits etc. often contain a high amount of calories but lack in beneficial nutrients and fibre.
Why do we need protein?
Part of all cells and tissues in the body are made up of proteins, including muscle tissue, internal organs, skin, hair and nails. Protein is therefore essential for growth, repair, formation of new tissues and maintaining good health.
How much protein should we have?
For the general population the recommended protein intake is 0. 8 – 1g per kg of body weight (per day). So for example a woman weighing 60kg would have a requirement of between 48 and 60 grams of protein per day. However for those who participate in exercise or sport on a regular basis there is additional protein needs. This is because there is an increased breakdown of protein during, as well as straight after exercise and so additional protein may be required to support repair and growth within the body. The current recommendation is 1.3-1.8g per kg of body weight (per day).
Types of protein
Protein can come from animal sources (such as meat) or plant sources (such as beans). Sources of protein include meat, fish, eggs, milk, cheese, cereals and cereal products (e.g. bread), nuts and pulses (beans and lentils).
Animal sources of protein are often thought of as a better ‘quality’ of protein because of their amino acid ratio (the building blocks of protein) compared to vegetable proteins. Animal sources of protein (e.g. meat) tend to contain higher amounts of essential amino acids. Because they contain a higher ratio of amino acids this means that these proteins are better absorbed and used in the body for tissue growth more easily, compared to foods that contain only some essential amino acids. If you choose to follow a diet high in animal protein try to eat leaner meats and low fat dairy products so that your saturated fat intake is not high.
However foods that don’t contain all the essential amino acids but contain some of them can be combined with other foods to make complete proteins increasing the absorption and protein use in the body (this is called protein combining or protein complementing). Examples include: rice with beans; hummus with pitta etc. Therefore you can get a perfectly good amount of protein by eating plant sources of protein.
Why do we need fat in the diet?
Cell membranes are made up of mainly fats. Fat also supplies us with the fat soluble vitamins (A, D, E and K) as well as helping with the absorption of these vitamins. Fat acts as an insulator in the body as well as being a form of protection from damage to organs. Fat provides essential fatty acids needed for the body and the brain and is also used as another source of energy in the body. Fat also helps food to taste good!
How much fat should we have?
A healthy person should aim to get between 20-35% of their total calories from fat, and most of this being unsaturated fat. The amount of fat a person consumes depends on their overall diet and goals.
Types of fats – what types of foods should we eat?
Trans fats are formed when oil is hydrogenated to make them harder. Trans fats can be found in foods such as biscuits and cakes, and consuming too many trans fats can increase cholesterol leading to heart disease and strokes. However trans fats are not a great concern in the UK as they have been removed from many food products over the years. Saturated fats can be found in sausages, pies, hard fats (such as butter, lard, ghee), biscuits, cakes and pastries. Although it is ok to have saturated fat in the diet, too much fat is believed to increase blood cholesterol. Unsaturated fats (polyunsaturated and monounsaturated) may help to maintain healthy cholesterol levels. These fats can be found in oily fish (e.g. salmon, sardines, mackerel), as well as plant food sources such as nuts and seeds, olive oil and avocados. We should try to have mainly unsaturated fats in the diet.
A gram of fat provides us with around 9 calories whether that is saturated or unsaturated, so smaller portions of fat should be eaten if you are considering calories.