The GI factor: a solution to weight control, sports performance and blood sugar control

GI stands for Glycaemic Index and it is a relatively new way of classifying carbohydrate foods. In the past carbohydrates were classified as simple sugars such as glucose or fructose (fruit sugar) or complex carbohydrates such as starches and dietary fibre (bread, cereals) and those in between such as lactose (milk sugar). However this does not tell us how the carbohydrate affects our body. The glycaemic index is much more specific because it tells us how quickly sugar levels rise in the blood after eating food containing carbohydrate. It is this rise in blood sugar level or “glycaemic” response that determines the GI of a particular food 

Our bodies are unique in the way they breakdown carbohydrates so you would imagine that the glycaemic response would be different from person to person. Researchers have got around this by testing at least 10 people and taking an average. The GI of foods are then ranked from 0 to 100. Foods with a lower GI have a smaller more sustained rise in blood glucose and this is preferable in conditions such as diabetes, weight control and endurance sports.

Foods with a higher GI supply glucose more quickly to the body but for a shorter time. This is useful when a person is experiencing a “hypo” from low blood sugar - dizzy, light headed, nauseous. High GI foods provide a quick acting source of energy to replenish supplies particularly after exercise. In general foods with a GI below 40 are low, between 40 – 70 moderate and above 70 high.

The Average Glycaemic Index of some carbohydrate-containing foods. Go to www.glycemicindex.com for a full database of foods.

(Note that GI varies between brands of food and with processing and cooking)

Breakfast Cereals

Weetabix          75

Cornflakes        84

Rice Bubbles    88

All Bran            42

Oat Porridge    42 

Grains/Pasta    

Basmati Rice    59

Egg Fettucini     32

Spaghetti          41

Bulgur(burghul)48 

Bread/Crackers

White Bread     70

Wholemeal       77

Mixed grain      45

Pita Bread        57

Fruit loaf           47

Water cracker  78

Ryvita               69 

Vegetables

Carrots             49

Parsnip             97

Green peas       48

Potato(baked)  85

Sweet potato    54

Sweetcorn        54 

Legumes

Baked beans    48

Chickpeas        33

Lentils              29 

Fruit

Apple               36

Banana             53

Grapes             43

Watermelon      72

Orange             43 

Dairy Foods

Skim milk         32

Low fat yoghurt            33

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The Uses of Glycaemic Index

1.      Diabetes

People with diabetes have problems controlling blood sugar levels because they either don’t produce enough of the hormone insulin or the insulin is not effective in its job of moving sugar from the blood stream into the cells to be used as energy. Diabetics may feel very tired, urinate a lot and feel very thirsty. Diabetics can use GI to their advantage by choosing foods that have a gradual and sustained rise in blood sugar placing less stress on the body. 

2.      Weight Control 

People wanting to loose weight can choose foods with a low GI because they satisfy hunger more and feel more filling. Many low GI foods such as fruits, vegetables and wholegrains are high in fibre and low in fat providing nutrients without excess calories. 

3 Sports Performance

Low GI foods eaten before prolonged strenuous exercise have been found to increase endurance time and provide higher concentrations of blood glucose towards the end of exercise. Conversely, high GI foods such as sports drinks help to replenish the muscle’s energy store (glycogen) following exercise leading to quicker recovery time. 

Meal suggestions for low GI

Breakfast:

Porridge with skim milk, honey and banana

Fruit smoothie made with low fat yoghurt/soy milk, fruit and honey

Pita bread/mixed grain toast with low fat spread 

Lunch

Sweetcorn and tuna salad with low fat dressing

Lean turkey with salad on mixed grain bread

Lentil soup/Minestrone/Chicken noodle soup with ryvita crackers

Hommos, tabbouleh and pita bread

Baked beans on mixed grain toast 

Dinner:

Stir fried noodles with chicken and vegetables

Basmati rice with dhal/lentil curry

Grilled fish with sweet potato and vegetables 

Snack

Fresh fruit

Low fat yoghurt

Toasted fruit bread

oat cake/ryvita

mixed nuts and seeds

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