View report page

at an optimum rate. If there is an excess growth rate, maybe in advance of
the optimum, then a child will tend to store carbohydrates and fats and be
overweight. If the supply of constituents is insufficient, the amount of growth
is slowed down; growth rate is then less than the optimum, so that a child has
no fat for storage and will be quite thin. In the body, the mechanism for
controlling the accuracy of the energy balance with the amount of food eaten
must be astonishingly accurate, for as Professor McCance1 of Cambridge
points out, if the mechanism is out of adjustment by as little as one-thirtieth
of an ounce per day, this would amount to a gain in weight of about fifteen
pounds in twenty years. This is about the normal amount of middle-age
spread in the forties.
Regulating Requirements.
We use up energy when we are asleep, sitting, dressing, walking, playing,
doing our work or merely idling about. The average man needs about 3,000
calories per day in food requirements to balance his energy expenditure. But
individuals vary widely from this average, one person requiring more and
another person less, and each individual himself varies in his requirements from
day to day, depending on the circumstances in which he is required to expend
energy; yet in the long run the balance over a number of years is very exact,
The balance cannot be kept good by any conscious effort, because a child of
eight months can regulate his own rate of growth automatically, and all animals
do the same. In primitive times food must have been scarce, and cooking, if
any at all, exceedingly simple. The survival of the fittest will have been in
those who had hearty appetites, could eat simple uncooked food without
indigestion, and who developed into shapes tending to swiftness rather than
fatness. Those people who are overweight are so because they live in a civilised
world with plenty to eat, and their regulation mechanism has broken down,
The exact mechanism which regulates appetite is not known; it may be regulated
by the amount of glucose circulating in the blood which affects certain
sensitive cells in the brain; but other things, such as smell, sight, hearing and
memory, are all associated. The regulating mechanism of a person may break
down in a number of ways; the result of course is an increase or decrease in
weight. Decrease from shortage of food in time of war or famine is obvious;
also from illnesses and afflictions such as obstructions of the stomach or bowel
which interfere with the proper intake of food. Expectant and nursing mothers
often consume enormous quantities of food in preparation for the developing
baby and its feeding. Some people overeat because it gives them a sense of
wellbeing and freedom from care. Food acts as a sedative; after a hearty
meal we feel less anxious, less inclined to restless activity, and more content
with the world in general. It may be that food supplies some substance soothing
to the nerves. Other people take a sort of perverted pride in being
excessively fat. Under the stress of emotion people tend to undereat, as
when worries and troubles overtake them. Indeed, any kind of emotion can
allay appetite, such as unsatisfied love, or a desire to attract attention by fasting
or refusing food.
A change of habit can lead to increased weight, such as when a man gives
up walking or cycling and goes by bus or car instead. As age advances, the
regulating mechanism seems to weaken with a consequent tendency to put on
weight. In extreme old age the desire to exert oneself, to acquire the necessary
amount of food may fail completely. Some people, however, following a
1 McCance, R. A. (1953). Lancet II. 739.
8