|
Appetite – Learning to
Stay in Charge
 |
|
Each of us has a
unique, individual response to the world around us. This applies
to all elements of our lives, including how and when we choose
to eat food.
At a basic level, decisions to eat are governed by the
sensations of hunger and appetite. These sensations are governed
by the central nervous system and are fundamental to the body’s
ability to regulate total food intake and in turn total energy
intake. However, it is very clear that this control system does
not always function as accurately as it might – in particular
the drive to consume more energy than is required seems to be
rather strong. A tendency to consumer more energy than is
necessary to maintain energy balance (where energy value of food
consumed = energy expended by the body) inevitably leads to
weight gain as excess energy consumed is converted to fat
deposits in the body.
Appetite experts know there are many factors which influence
this drive to consume food. The chemical and physical
composition of foods consumed, and the body’s digestive response
is one factor, but social and emotional forces also play an
important role, and at the individual level the relative
strength of these appetite triggers may vary considerably.
What is the difference between hunger and appetite ?
The sensation of hunger is one experienced by everyone at some
time in their lives. Hunger is a physiological state in which
the body is using one or more nutrients at a faster rate than
they are being replenished, and generates strong responses such
as thinking about food, and taking action to find and consumer
food. The biological signals that indicate hunger due to energy
(calorie) imbalance are complex, but it is known that blood
glucose levels, and their rate of change is an important factor.
The hunger response is strong, and hence, if you wait to eat
until you are physiologically hungry, you may eat four or five
times the amount you need to fill the nutritional stores. Many
people skip meals and then "pig out.", and numerous studies have
found that those who regularly skip meals are more likely to be
overweight or obese than those who eat more regularly.
Appetite is a more subtle, and complex interplay of responses to
both hunger/satiety sensations, the presence of foods, and in
some cases non-food factors such as emotional state. Appetite
might best be described as a motivation to eat, which remains
until a sense of satiety is achieved. However, the sensation of
satiety goes beyond meeting basic nutrient or energy needs,
stimulated by other factors such as the palatability of the
foods available.
Understanding our own individual appetite triggers and how to
anticipate and manage them, may therefore be key to personal
long-term weight management.
How does composition of food influence appetite ?
Energy density
The three macro-nutrients (carbohydrates, protein and fats) are
the three primary sources of energy in our diet. Each of these
energy sources will satiate appetite, but research has found
that the satiating power of each is rather different. In general
fat has the lowest satiating power, carbohydrates have an
intermediate effect, and proteins have found to be the most
satiating.
In addition to this, research has also demonstrated that the
energy density of foods consumed has a direct impact on appetite
and hunger or the sense of fullness. Independent of fat content,
low energy dense foods have greater satiating power than
energy-dense foods on a calorie for calorie basis. Thus foods
with high water or foods high dietary fibre content will satisfy
appetite at lower total energy value than those with a
comparatively higher fat, protein or carbohydrate content. For
example steamed greens will be more satisfying on a calorie for
calorie basis than fried, because fat content will be higher,
and water content will be reduced as a result of cooking at very
high temperatures.
Glycaemic Load
In recent years there has been great interest in exactly how
carbohydrate foods can impact appetite. The healthy human body
control its blood sugar levels very accurately, and blood sugar
is one of the many internal systems the body uses to regulate
energy balance - falling blood sugar levels act as an appetite
cue, and raised levels send signals to the satiation signals to
the brain. The glycaemic load is a way of measuring the effects
of carbohydrate foods on blood sugar. Foods such as white bread
and potatoes have been found to raise blood sugar rapidly,
provide the sensation of appetite for a relatively short period
of time. If eaten in large amounts this effect is magnified.
Foods such as lentils and pasta release glucose into the blood
stream more slowly and delay the onset of hunger sensations for
longer. |
|
|
The glycaemic load is the sum total of both the rate at which
the foods are digested, and absorbed into the bloodstream as
glucose, and the quantity of the food or meal eaten. Thus a meal
which contains only a small amount of food rapidly digested and
absorbed mixed with larger amounts of ingredients which are more
slowly absorbed may have a high satiating power and low
glycaemic load. For example, glutinous (sticky) rice has a
rather high glycemic index, but eaten with durian or mango and
coconut milk results in only moderate glycemic load.
In Australia foods have begun to include glyacemic load values
on the labels. As a guide a GL of 20 or more is high; GL of 10
or less is low.
How does the presentation and palatability of food affect
appetite ?
It is very clear, that the temptation to eat more is greater if
the food available is especially palatable. The pleasure derived
from eating is directly linked to its palatability: Human beings
have a natural preference for sweetness, and dislike for
bitterness – this is thought to be an evolutionary measure to
protect against consumptions of foods that are poisonous. Many
high-fat foods provide pleasurable sensory experiences such as
the sensation of ‘creaminess’. Palatability is also affected by
the other experiences associated with their consumption. For
example foods associated with celebrations such as Chinese moon
cakes, may seem especially attractive because of long-standing
memories of celebrating the mid-autumn festival.
Research has also found that increasing the variety of foods
available stimulates appetite.
Experts believe the introduction to a variety of foods at one
sitting also has an effect on appetite. Foods offering different
textures, flavours and colours stimulate our appetite in
different ways and encourage individuals to try many foods.
For example studies find that individuals consumr more calories
when faced with an extensive buffet, rather than just a few
choices.
Studies also find that how much individuals choose to eat is
directly relate to how much they are offered. For example,
someone given a moderate-sized bowl of rice and sauces may
decline a second helping, because they feel satisfied, but the
same person offered the same foods in larger quantities, will
almost always eat more of the larger bowl. Following the old
maxim ‘out of sight, out of mind’ therefore might be wise advice
for those trying to lose or maintain body weight, for example by
taking care to keep only the food you intend to eat on the table
or plate, and removing the temptation to eat more than is needed
just because it is there.
How do emotions affect appetite ?
Food is not only a source of essential nutrients, food is also a
source of tremendous pleasure, and is frequently a symbol of
happiness, celebration, friendship, or commitment. These are
very positive and important roles of food in the society in
which we live. However, the social pressures to consumer more
than we need to remain in energy balance can be quite strong.
For example, many of us expect to overeat during the New Year
festivities, or feel obliged to eat foods provided by welcoming
host, even when not hungry.
Occasional periods of over-consumption are perhaps inevitable.
In these instances, it is important to enjoy and participate in
the social occasion, but recognise that once over, individual
control of appetite is not only possible, but a priority.
Instead of perceiving small amount of weight gain as a failure,
concentrate on the achievement first of stopping any further
weight gain. This sense of achievement will support the next
stage which is reversing the small weight gain by returning to
sensible, balanced and planned eating patterns.
Food may also be used a focus of consolation when faced with
social or emotional challenges. It may be used to help meet
emotional needs such as the need for comfort, fun, or security.
Many of us from time to time have found ourselves nibbling,
bingeing, or rooting in the fridge for a little something nice
to eat. Emotionally-driven eating may not only result in weight
gain, but in the long-term add to inner sense of discontent in
response to the undesired weight gain and sense of not being
able to control appetite.
For those who suspect their appetite is sometimes driven by
negative or positive emotions, it may be a good idea to create
your own food and mood log. Record for a two week period what
you eat what time you eat and what mood you are in before and
after you eat. This will provide insight into the triggers that
prompt emotionally-driven eating. Once the triggers are
identified, you will need to spend time planning alternative
activities which don’t involve food to meet these emotional
needs, such as taking a walk, texting friends, writing down
what’s troubling you. That way, the next time the urge to find
food in response to uncomfortable emotions, you have an
alternative activity ready and waiting.
Remember, that emotionally-driven eating ‘coping strategies’ are
likely to be well established and it may take some time to undo
these behaviours, so allow time to introduce these new habits
and expect to adjust and improve with time.
-
Some Practical Tips
| |
