1. Diet refers to the food we eat.

 

2. A balanced diet is a diet that contains all the seven classes of food in the right amounts.

 

3. The amount of food or energy that a person needs depends on several factors:

(a) Age

- A teenager needs more food, especially proteins, than an old man who is no longer growing.

(b) Body size

- People with bigger body sizes require more energy than those with smaller body sizes.

(c) Sex

- Males require more energy than females because males have a smaller amount of fatty tissue in their body. Thus, heat loss is faster in males than in females.

(d) Occupation

- A person who does heavy work needs much more energy than a person who is only moderately active.

(e) Climate

- People living in cold countries lose more heat to their surrounding compared with those living in the tropics. They need more energy in order to maintain their body temperature.

(f) State of health

- A person suffering from hyperthyroidism (overactivity of the thyroid gland in the neck) requires more energy.

 

4. The amount of food eaten must balance the quantity of energy used. If we eat too much, we will gain weight and become obese. If we eat too little, we will lose weight, feel weak and may suffer from deficiency diseases.

Group	Age (years)	Sex	Activity	Energy requirements (kJ)
Child	7	Female	Moderate	8500
		Male	Moderate	8500
Teenager	15	Female	Moderate	9500
		Male	Moderate	12 500
Adult	23	Female	Moderate	9500
		Pregnant mother	Moderate	10 000
		Breast-feeding mother	Moderate	11 500
		Male	Moderate	11 500
		Female	Active	12 500
		Male	Active	20 000
	65	Female	Moderate	6500
		Male	Moderate	8500

 

5. Figure below shows a food pyramid. It shows that we should consume more bread and cereals than fats and sugar.

 

 

 

 

 

 

 

 

Caloric value of food

1. The energy content of food is indicated by its calorific or energy value.

 

2. Carbohydrates, fats and proteins supply us with energy.

 

3. The energy value of food is measured with a calorimeter.

 

4. The unit of energy in food can be measured in calories (cal) or joules (J) where 1 cal equals
4.2 J.

                                1 cal = 4.2 J

        Energy value of carbohydrates, protein and fats

Class of food	Energy value (kJg-1 )
Carbohydrates	17
Proteins	18
Fats	39

Composition and energy value per 100 g of foodstuff

Foodstuff	Carbohydrate (g)	Protein (g)	Fat (g)	Energy value (kJ per 100 g)
Rice	78.0	7.1	1.1	1508
Potato	18.9	2.0	0.1	344
Bread	51.3	7.2	1.8	1029
Refined sugar	100.0	0	0	1626
Margarine	0.4	0.6	81.0	3024
Cow’s milk	5.0	3.5	3.5	273
Fresh anchovies	0	17.9	1.1	344
Dried anchovies	0	46.0	3.0	937
Crab	2.0	18.0	1.5	395
Soya bean	31.3	38.5	18.0	1407
Peanut	23.4	25.6	43.3	2293
Cabbage	5.7	1.6	0.1	105
Carrot	9.1	1.1	0.2	168
Onion	9.0	1.4	0.2	168
Cucumber	3.0	0.8	0.1	55
Pineaple	12.2	0.5	0.2	197
Watermelon	6.0	0.5	0.2	105

Energy value of some local food

Food	Quantity	Energy value (kJ)
Egg	1 medium size	300
White bread	1 piece	400
Cornflakes	1/2 cup	200
Kuih seri muka	1 piece	400
Doughnut	1 piece	300
Apam balik	1 piece	480
Curry puff	1 piece	180
Fried rice	1 plate	3000
Fried noodles