Guide to nutrition

• What are calories/kilocalories?

• Where does the energy in food come from?

• What is the recommended amount of protein, fat and carbohydrate in the diet?

• What are macronutrients and micronutrients?

• Current thinking on how the body uses and stores the macronutrients

• What is your metabolic rate?

• Can you increase your metabolic rate?

• Does food contain a single nutrient or is it made up of a mixture of nutrients?

• What makes up a bad diet?

• Is it more fattening to eat late at night?

• Is there any such thing as a slimming diet that works?

• What are calories/kilocalories?
You will always see kilocalories (kcal) and kilojoules (kJ) on food labels. They are the units which tell you the amount of energy in a particular food.

•1 kilocalorie (kcal) = 4.18 kilojoules (kJ)

• Where does the energy in food come from? There are four types of fuel in food and drink which provide energy. They are carbohydrate, fat, protein and alcohol. Each of these fuels supplies a different amount of energy.

• Carbohydrate = 4kcal
• Fat = 9kcal
• Protein = 4kcal
• Alcohol = 7kcal

• What is the recommended amount of protein, fat and carbohydrate in the diet?
Recommended dietary allowances have just been published for Irish people and they vary according to your age, current weight, and activity level. For specific information on your needs, contact the Food Safety Authority of Ireland, email info@fsai.ie or you can access their website at www.fsai.ie

• What are macronutrients and micronutrients?
The macronutrients supply energy and are: protein, carbohydrate and fat. Micronutrients describe vitamins and minerals. Although these nutrients are essential, they are only needed in very small amounts. They do not contain energy.

• Current thinking on how the body uses and stores the macronutrients
There is evidence to suggest that the body has a preference for carbohydrate and uses this source of energy first. However, if alcohol is consumed it will be metabolised first because the body cannot store it and because high levels are toxic. After carbohydrate, the body uses protein and finally fat. This helps explain the current drive towards keeping fat levels in the diet low.

• What is your metabolic rate?
It is the rate at which your body uses energy.

• Can you increase your metabolic rate?
Yes. By increasing the amount of lean tissue (muscle mass, through training) you can increase your metabolic rate. Unfortunately, smoking also increases it. This is often the reason young girls say they start smoking.

• Does food contain a single nutrient or is it made up of a mixture of nutrients?
Most foods contain a mixture of carbohydrate, protein and fat as well as a range of vitamins. This is why a healthy diet is made up of a variety of food and also why it is impossible to say that any one food is a bad food.

• What makes up a bad diet?
While you cannot say that one particular food is bad, you can have a bad diet, simply through lack of variety. Too few foods, for example, will mean that a diet can be lacking in energy or essential vitamins or minerals. Take the person who eats fish and chips on a Friday. There is energy, protein, fat, carbohydrate, vitamins and minerals in this meal and that is what you need. However, if this person ate fish and chips every day for their dinner, this would be a bad diet. There is not enough variety.

• Is it more fattening to eat late at night?
No, as long as it is not a second dinner. However, eating shortly before you go to bed will probably be uncomfortable. There are many jobs that involve shift work and eating late at night is the only option. Just allow a couple of hours before you go to bed to avoid any discomfort.

• Is there any such thing as a slimming diet that works?
Yes. Contact a Dietitian or Clinical Nutritionist for safe, professional and personalised advice. The Irish Nutrition and Dietetic Institute will be able to let you know of a dietitian in your area.

Nuala Collins, BSc, Nutrition and Dietetics

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