Dietitian Talk - Kerry Otto - 11/9/02
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Carbohydrates are broken down at different rates.
Diets have changed over the last 25 years especially for
diabetes, with diabetes now the emphasis is on the prevention of
heart disease - exercise and weight control
Weight loss diets have changes as well - focusing on increasing
the metabolism and burning the weight off
The body will breakdown muscle as a source of glucose.
Breaking down muscle will in the long term reduce the metabolic
rate.
Women are less able than me to use adipose tissue (fat) as a
fuel.
Muscle producing exercise is seen as the most beneficial for
weight loss - Cardio and strength.
Diets are focusing on eating enough rather than starvation diet.
Emphasis is still on low fat foods.
We store 99% of the fat in our diet as body fat, only about 1% is
used as fuel. The metabolism needs to be up in order to burn fat.
Carbohydrate is our primary fuel source.
The G.I. Factor is a ranking of foods based on the overall effects
on blood sugar levels
G.I. is used for diabetes, appetite control, sports performance,
reducing risk of heart disease
Also need to take into account fat content and nutrition
G.I. low foods - slow release of glucose into the blood stream
Over production of insulin may lead to heart disease and
diabetes
Factors affecting the G.I. of food products
1. Low degree of starch gelatinisation - the less gelatinised
(swollen) the starch the slower the rate of digestion. e.g.
Spaghetti
2. Physical form of the food - the fibrous coat around beans
and seeds and intact plant cell walls act as a physical barrier,
slowing down access of enzymes to the starch inside. e.g. grain
bread, beans
3. High amylose to amylopectin ratio
4. Fibre - viscous, soluble fibres increase the viscosity of the
intestinal contents and this slows down the interaction between
starch and enzymes
5. Sugar - the digestion of sugar produces only half as many
glucose molecules as the same amount of starch (the other half
is fructose)
6. Acidity - acids in foods slow the rate of gastric emptying,
thus slowing the rate of digestion. e.g. oranges, vinegar
7. Fat - fat slows down the rate of the stomach emptying,
thereby slowing the digestion of starch. e.g. chocolate
How Scientists Measure the G.I. Values of Food
1. An amount of food containing 50g CHO (250g spaghetti) is
given to 8-10 volunteers to eat
2. Over the next 2 hours blood sugar levels are taken every
15minutes
3. Blood sugar level is plotted on a graph and area under the
curve is calculated
4. This process is repeated several times
Book: The G.I. Factor
This is a good book for diabetics.
Note: When looking at G.I. values they need to have been
calculated using Australian foods as Australian foods have lower
values than American Foods because Australian foods are
sweetened with cane sugar not corn sugar like American foods.
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Only foods with absorbable carbohydrate have a G.I. value
Basmati rice and Doongara rice are very good
Avoid
fat
especially
saturated
fats.
Good
fats
(monounsaturated fats) are in foods like avocado and olive oil
(not heated as the molecular structure changes when heated)
Day to day eating try to keep to low G.I. foods
Low Carbohydrate diets are linked to:
Hunger
Glycogen depletion
Muscle breakdown
Poor nutrition
Dehydration
Fatigue
Dizziness
Bad Temper
Low carbohydrate diets are not sustainable in the long term
Good Diet:
 Eat lots of fruit and vegetables to get antioxidants and
assist the immune system
 Eat regularly throughout the day
 Eat foods with fibre
 Eat lean red meat from pasture fed animals
 Eat skinless chicken
 Eat lots of fish
 Include legumes and pulses in the diet
 Have only moderate amounts of alcohol