When they are digested all carbohydrates convert to blood sugar but some are digested and converted to blood sugar more quickly than others. The Glycemic Index (GI) is a way of classifying carbohydrate foods according to the speed at which they release their sugars into the blood.When blood sugar levels increase, the body produces insulin. Insulin (a hormone produced by the pancreas) has several functions including regulating blood sugar levels, storage of reserves and stimulating hunger.   Insulin is released to remove the excess sugars from the blood and store them as glycogen in the liver, muscles and in the body’s fatty tissues for future use.  Eat too much sugary food and you stimulate an over production of insulin resulting in too much blood sugar being removed and stored. Your blood sugar levels then fall below where they need to be, causing your body to “crash” and become hypoglycaemic. You become lethargic and begin to crave sugars; you reach for sugary foods in order to satisfy those cravings and the whole cycle begins again. With glycogen being stored each time the cycle is repeated, over a period of time weight gain will result.

If you are trying to lose weight you need to avoid creating blood sugar highs and lows and to try instead to keep your blood sugar levels as steady as possible.  One way of doing this is to reduce your consumption of high GI foods and to replace them with low GI, steady sugar releasing foods.  Insulin stimulates hunger so by keeping your blood sugar levels constant and reducing your insulin levels you will delay the return of hunger, helping you to eat less.

Detailed below are some food categories, with examples of foods in each category having high, intermediate and low GI ratings.  Take a look and see if there are any low GI foods which you can substitute for high GI foods currently included in your diet. Be aware that on its own the GI of a food does not make the food itself “good” or “bad”.  Some high GI foods like potato and watermelon make a valuable nutritional contribution to our diet, while some low GI foods, eg corn chips and chocolate which are high in saturated fat, are not health promoting despite being low GI foods.  Aim to keep your blood sugar levels as constant as possible - with just a little planning you can organise your daily food intake so as to avoid the sugar and insulin highs and lows which can be so detrimental to your weight loss goals. 

Food Category High GI Rating
(over 70)
Intermediate GI (between 55 & 70) Low GI (less then 55)
Breads, Grains & Pasta Bagel
White Bread
Wholemeal Bread
Pitta Bread
Brown Rice
Multigrain bread
Linguine
Whole wheat spaghetti
Fruits Dried dates
Watermelon
Pineapple
Raisins
Mangoes
Banana
Grapes
Apples
Plums
Pears
Snacks, Cakes,Biscuits & Sweets Doughnuts
Waffles
Jelly Beans
Ryvita
Croissant
Rye crisp bread
Unsweetened popcorn
Chocolate*
Potato chips*
Crisps*
Corn Chips*
Cereals Rice Krispies
Cornflakes
Weetabix
Shredded wheat
Museli
Mini wheats (wholemeal)
Porridge (non instant)
All Bran
Potatoes & Roots Parsnips
Mashed potato**
Jacket potato**
Beetroot
New potatoes
Boiled potatoes
Sweet potatoes
Yams
Vegetables/ Legumes N/A Sweet Corn Green Peas
Carrots
Green Beans
Peppers
Broccoli
Cauliflower
Chick peas
Haricot Beans
Lentils
Kidney Beans
Dairy Ice Cream N/A Milk (semi skimmed & skimmed)
Low fat fruit yoghurt
Soya Milk

Note:  The foods marked * above are high in empty calories while those marked ** are low in calories and good nutritious foods despite having a high GI rating.

If you are a Fitness Video Podcast Gold or Silver Member and would like help to plan your daily food intake, your Personal Training Mentor will be happy to help.