The Balanced Diet
No single food contains the correct proportions of all essential nutrients.If any nutrient is eaten in excess,or is deficient,health may be adversely affected.Example, a high energy diet can lead to obesity,and an iron-deficient one to anaemia.So a balanced diet is achieved by eating a variety of foods.
A balanced diet is important in maintaining a healthy body weight,which can be assessed by calculating body mass index(BMI).
Body mass index: WHO classification
Calculation of BMI:
Body Mass Index(BMI)=Weight(kg) / Height(m2)
Interpretation of BMI
<16 Severely underweight
18.5-24.9 Normal range
>40 Severely obese
In which category do you belong?
An important dietary consideration is the amount of energy required.This should meet individual requirements.
Daily energy requirements depend on several factors including basal metabolic rate,gender,age and activity levels.Dietary carbohydrates,fats and proteins are the principal energy sources and fat is the most concentrated form.
Dietary energy is correctly expressed in joules or kilojoules(kJ) although the older terms calories and kilocalories are also still used.
Recommendations for daily food intake according to British Nutrition Foundation (2009) sort foods of similar origins and nutritional values into food groups, and advise that a certain proportion from each group be eaten daily. If this plan is followed, the resultant dietary intake is likely to be well balanced. The 5 food groups are:
- Vegetables and fruits.
- milk and dairy products.
- Drinks and foods high in fat and/or sugar.
- meat,eggs,fish, beans.
Milk and dairy foods
Foods that fall in this category provide protein and minerals including zinc and calcium.Some are also a source of vitamins A,B2 and B12. They include milk,yoghurt,cheese .They often contain substantial amount of fat.Intake should be limited to 3 servings per day.
1 serving = 200ml milk, 30 g cheese or 150 g yoghurt.
Vegetables and Fruits
Foods in this category include fresh,canned and frozen products,100% fruit or vegetable juices.These foods provide fibre,vitamin C,folic acid and carbohydrates.A minimum of 5 portions per day is recommended.
One portion= 1 piece of medium fruit eg orange,apple,3 tablespoon of cooked vegetables,1 bowl mixed salad:150 ml fruit juice.
This group includes meat products.Moderate amounts should be taken because many have a high fat content.It is good if we have one portion of oily fish eg salmon,fresh tuna twice a week.This group provides protein,iron,vitamin B and D.Vegetarians have beans,pulses eg lentils in this group.Beans and pulses are rich source of fibre.
Drinks and foods high in fat and sugar
These foods include oils,butter,fried food including chips,sweets,cream,jam,chocolate,soft drinks.Foods in this group should only be used sparingly,as they are high in energy and have little other nutritional value.
This group should make up 1/3rd of the diet.Potatoes,yams are classified as 'starchy carbohydrates'.These foods are sources of fibre and carbohydratesthat provide sustained energy release.Some also contain iron and B-group vitamins including folic acid.
The British Nutrition Foundation has suggested fluid intake of 1.5 to 2 litre per day.This includes water,tea,squash,fruit juice,coffee.Alcohol intake should not exceed 3-4 units per day for men and 2-3 units per day for women.