Of
course, we all know that the main role of food is to satisfy hunger and
to provide essential nutrients for growth and maintenance of health –
yet so much of what we choose to eat is influenced by other factors such
as the palatability of foods available, our emotional state, and social
factors, such as the expectations of those around us.
So our
appetite usually reflects a combination of both basic physical needs and
other social and emotional motives. Understanding what these are and how
they can be modified may be key to effective weight management.
Researchers are still working to unravel all the factors that influence
what we eat and why, but this article highlights some of the factors
identified so far…
What make
us feel full?
During a
meal our stomach expands and the internal nerve receptors sense the
volume of food and
the pressure on
the stomach wall. These receptors send signals to the brain via the
vagus nerve causing the sensation of fullness. When the stomach
contracts and empties, the sense of hunger is triggered again.
Some
foods contribute a feeling of fullness more than others, those which
contribute the greatest sense of fullness are said to have high
satiating power, and those which give the least sense of fullness for
any given energy (kilo- calorie) content, have low satiating power:
While protein seems to stave off hunger for longer than carbohydrate,
fat exerts the weakest effect on satiation. This probably accounts for
the many studies that have found a high fat diet is more likely to lead
to passive over-eating, and resultant weight gain.
Energy
(kilocalorie) values of foods of course do not reflect these differences
in satiation power: For example, in one study of 38 common foods, men
and women consumed foods with same energy contents and their feelings of
fullness were recorded every fifteen minutes for two hours. The most
satiating foods were those with high levels of protein (including fish,
meat, beans, lentils and eggs), dietary fibre (such as wholegrain breads
and cereals) and water (particularly fruit and vegetables). Foods with
low satiation power were those with the highest proportion of energy in
the form of fat, for example baked goods.
Glycaemic Index
In recent years there has been great interest in exactly
how carbohydrate foods can impact appetite. Glycaemic index (GI) is a
way of measuring the effects of carbohydrate foods on blood sugar. The
index ranks foods on a scale of 0 to 100. Foods which raise blood sugar
the highest and most quickly such as white bread and potatoes have a
high GI and those with low GI such as lentils and pasta
release glucose into the blood stream more slowly. Those with a low GI
will delay the onset of hunger sensations for longer and thus are
helpful for individuals who are trying to limit their energy intake. It
is important to consider the total amount of food consumed and other
foods included in a meal or mixed dish –this is known as the glycaemic
load (GL), and is a more accurate indicator of how the body reacts to a
typical mixed ingredient meal. An extensive list of both GI and GL
values, compiled by the University of Sydney can be found at
http://www.glycemicindex.com
Emotional Eating
Many of us have from time to time
found ourselves eating when not actually hungry.
Behaviours such as nibbling, bingeing
or rooting in the fridge for a little
something, in many instances, are
examples of emotionally driven
eating. Diet counselor and university dietetic
lecturer J.McFadden in her book
‘Diet
No More’
describes how unmet
emotional needs can become internal drivers for eating when not
physically hungry. Unconsciously we may attempt to
satisfy unmet needs for love, power, fun, freedom or survival through
food.
McFadden
recommends that the next time you find yourself reaching for food when
not hungry, you allow yourself to eat your chosen food but try to tune
into the emotional urges that are driving you to search out food.
Part of the solution is listening to your body’
s signals of hunger and satisfaction, and then taking
some time to plan ways which don
’
t involve food to meet these emotional needs to help you
feel better, for example going for a walk, or writing down what is
troubling you. That means the next time the emotional triggers are
switched on, you have an alternative plan ready to put into action, and
feel more in control.
As
non-hungry eating habits are likely to be firmly entrenched, its
important to recognize that devising and establishing alternative coping
strategies is likely to be a long process. Therefore, developing
alternative coping strategies should be approached slowly and
incrementally to ensure new habits become long-term habits.
More
information on this approach to weight maintenance can also be found at
the website www.ifnotdieting.com
What is becoming apparent is that appetite is not only a
complex interaction of physiological and psychological responses, but
that the relative strength of these factors varies between individuals.
The evidence is growing that each of us must start to understand our own
personal profiles, so that we can learn to enjoy our daily diet, without
guilt, without eating more than we need and without feeling hungry
- bon appetit!
