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mid-day meal. The quantity of food we should take depends, in part,
on the mental and physical work we have to do, but, as I shall show,
that statement requires some qualification. Eat meat once a day only
and hardly ever at all if the blood pressure is high. I shall speak of
blood pressure in a moment. Old people should eat in strict moderation,
their food should be simple in quality and contain little or no
starchy foods. Everybody over 40 should take enough food to maintain
the lightest weight consistent with perfect health. It is sheer
nonsense for a man to think that at 55 he should weigh a stone more
than he did at 30. Simple diet consists of wholemeal bread—not white
bread—plain biscuits, plain puddings, vegetables, fruit, some meat,
fish, milk, butter and cheese. Take few condiments; never take
alcohol before night and take very little of it even then. A man of 4.0
or over should never drink beer, it makes him corpulent. Now, until
recent years everybody talked about the caloric value of food. If
soldiers were going on a route march, we worked out the number of
calories each man required. A small calorie is the amount of heat
required to raise one gramme of water through one degree Centigrade.
The large calorie is equal to 1,000 small calories. The caloric value
of any food is determined by a calorimeter, and is a measure of the
energy which is given out by the complete oxidation of the substance.
It was said that the food the average man required was from that
which yielded 2,500 or 3,000 calories. These calories were obtained
from certain proximate principles called proteins, carbohydrates and
fats, which, with salts and water, supplied us with our nourishment.
Further observations taught which foods supplied proteins and which
carbohydrates and which fats, and how the three proximate principles
acted. Thus, proteins are present in all animal foods, in eggs, and, to
a small extent, in cereals and pulses. Carbohydrates come from
vegetables, cereals, pulses and sugar, whilst fats are found in the fat of
meats, in butter, animal oils derived from fish and to a lesser extent
from vegetable oils. The proteins we eat make up the loss of structure
from wear and tear; carbohydrates and fats give heat and energy for
work. Fat supplies more energy than carbohydrates or proteins ; and
so, knowing these things, our physiologists proceeded to work out diets
which, by weight, would supply men engaged in active or sedentary
work with all that was required to keep a man or woman fit. It was
all very good, and though we must always make use of such information,
a change came over the scene when we discovered vitamins.