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this general rule are sugar and refined fats which are purely
energy-giving foods and contain no constructive or protective
nutrients.

It is clear that the need for energy depends on circumstances
such as the amount of muscular activity performed. For
this reason, men require more than women, and active people
more than inactive people. The period of most active growth
and of greatest activity for boys and girls is from 12 up to about
20 years. During this period of life both sexes require more
food of all kinds than adults. They require more constructive
foods because they are growing rapidly, more energy-giving
foods because, as a rule, they are more active than adults, and
more protective foods in order to balance the higher require-
ments for the other two classes of nutrients.

Constructive foods are however required throughout life
because a certain amount of wear and tear of tissues continually
goes on and this must be made good by the construction of new
tissue. Expectant and nursing mothers also require large
amounts of constructive foods, the former because she is building
up a new being within her own body, and the nursing mother
because she is manufacturing the materials (milk) which are the
sole nutriment of her infant during the early months of life.

CLASSIFICATION OF FOODS.

1. Energy-giving Foods.

Three classes of foods serve as sources of energy, examples
of which are given below: —

(a)
	Sources of
	(b) Sources of
	(c)
	Sources of

Carbohydrate.
		Fat.
	
	Protein.

Sugars.
	Starches.
	
	Animal.
	Vegetables.

Sugar.
	Flour.
	Butter.
	Milk.
	Pulses, i.e.,

Honey.
	Bread.
	Margarine.
	Cheese.
	peas, beans,

Treacle.
	Cake.
	Dripping.
	Eggs.
	lentils.

Syrup.
	Pastry.
	Cooking fat.
	Fish.
	Nuts.

Jam.
	Cereals, e.g.,
	Vegetable oils.
	Meat, including
	

	rice, tapioca.
	Bacon.
	offal.
	


	Porridge.
	Cheese.
	Rabbits.
	


	Potato.
	
	Poultrv.
	

Protein can be derived from both animal and ^vegetable
sources. That from animal sources is more valuable and more
readily assimilated than that from vegetable sources.

2. Constructive Foods.

(a)  Sources of Animal Protein as in 1 (c).

(b)  Sources of Vegetable Protein as in 1 (c).

(c)  Sources of Minerals:

Calcium.
	Phosphates.
	Iron.

Milk.
	Milk.
	Eggs.

Cheese.
	Cheese.
	Liver.

Eggs.
	Eggs.
	Oatmeal.


	Fish.
	Wholemeal flour.


	Meat.
	Lean meat, including offal.


	
	Green vegetables.