Human Nutrition

A HEALTHY DIET – HOW MUCH TO EAT? ❚
reluctant to eat an unfamiliar food just because
we were told it was healthy; the property of
healthiness would be included in the general
consideration of the food in deciding whether or
not to include it in the diet.
However, food that constitutes a ‘healthy
diet’ is in the main not very different from that
which makes up a less healthy diet – it is the
balance of the parts making up the total meal or
diet that is important. As has been said elsewhere
in this book, there are no ‘bad’ foods; it is
their place in the general picture of the diet that
is important. Some foods provide only a very
narrow range of nutrients, perhaps even just
one. If such foods comprise a substantial part of
the daily intake, the consumer will run the risk
of not meeting nutritional requirements for a
range of nutrients. The greater the range of
foods, the less likely are there to be ‘gaps’ in the
nutrient intake, and the more likely it is that the
consumer will meet the nutritional needs.
We are attracted by variety in foods, and
would find a diet containing just one or two
foods very monotonous. This might result in a
smaller intake of the foods. The converse is
also true: when presented with a variety of
foods, we move from one to another and are
likely to eat more. The appearance of a tempting
Activity 3.1
Make a list of foods that you usually eat during
the course of a week. Divide them up into four
columns: foods eaten at breakfast, lunch, evening
meal, and snack foods.
■ Is this easy to do? If so, you have got strong
ideas about what foods are appropriate at
what times, and in what meals. If you found
it quite hard to do, this may be because you
have a much ‘freer’ food structure, and the
items in your diet may serve several roles.
■ Check with a partner how easy their list was
to write into columns.
■ Finally, check how much agreement there is
between your list and your partner’s – do you
consider the same foods as appropriate at
particular times?
dessert after a filling meal can readily override
feelings of satiety, simply because of the novelty
aspect!
Selecting several foods is, therefore, beneficial
for our nutrient intake. Traditional meal
patterns can help us to decide on combinations
of foods to make up meals, as well as what
foods to have at specific points of our day. The
pattern of core, secondary and peripheral foods
discussed in Chapter 2 serves as a general guide.
It must be recognized that there is increasing
variation in this pattern. It is possible that, in
future generations, meals may be quite different,
although there are also signs of a ‘traditionalist
revival’, which may take us back to the
old-established food patterns.
A healthy diet – how much
to eat?
In addition to deciding what foods to eat, each
person makes a decision about the quantity to
consume. From experience we have learned
what is an adequate serving size for us and this
obviously varies between individuals.
Our ability to assess how much of a food we
would like to eat relies on learned responses
established during our childhood and added
to whenever a new food has been introduced.
The sensations arising from the stomach when
a particular serving size has been eaten will be
remembered and will help to determine our
behaviour in the future. Other reflex pathways,
linked to the metabolic consequences of the
meal, may also be part of the regulatory process.
It is believed that this type of learning is an
important component of the control of food
intake (as discussed in Chapter 2).
The variability of ‘normal’ serving sizes
between individuals is a dilemma for those
studying food intakes in populations. There is no
such thing as an ‘average’ serving size, which
would apply to everyone. However, for the sake
of expediency, such a measure is quoted and
used in many contexts. However, in relation to
this ‘average’, it is recognized that different
people will also have ‘large’ and ‘small’ servings.
Interpretations of these are also subjective and,
therefore, variable.
37