Spotlight on... low-GI

  • By
    Jo Lewin - Nutritional therapist

Eating foods that have a low score on the glycaemic index can keep blood sugar levels steady and can even help your body metabolise fat more efficiently. Nutritionist Jo Lewin explains how the diet works...

Spotlight on... low-GI

The glycaemic index (GI) was originally designed for people with diabetes to help keep their blood sugar levels under control. It is also a useful tool for non-diabetics in planning healthy meals and choosing foods.

The GI ranks carbohydrate foods based on the rate at which they are broken down into glucose. Too much glucose in the bloodstream triggers the pancreas to release a hormone called insulin to bring blood sugar levels back into the normal range. Consuming foods with a high-GI leads to high levels of circulating insulin levels, which we want to avoid.
 

How does it work?Sugar

Carbohydrates are found in starchy foods such as bread, pasta, potatoes and in sugary foods such as fruit, cakes, biscuits and honey. They provide the main source of energy, used to fuel every part of the body from the brain to our beating hearts (a bit like petrol in a car). All carbohydrates have the ability to raise glucose levels in the blood but the slower a carbohydrate is digested, the slower it releases energy - in the form of glucose - into the bloodstream and the lower its GI score. The faster a carbohydrate is digested, the more rapidly glucose levels in the blood rise, and the higher the GI score.

The speed at which this digestion to glucose occurs, and the amount it raises glucose levels in the blood is measured on the GI scale. Glucose, one of the most rapidly absorbed carbohydrates, has been given a score of 100.

 

Grapefruit, agave & pistachio salad How low-GI foods can speed up fat burning...

A sharp increase in glucose in the blood triggers the pancreas to release a rush of the hormone insulin, which removes any excess glucose. Insulin removes the surplus glucose from the blood and lowers the speed at which the body burns fat. A large surge in insulin, caused by eating high-GI foods, will start reactions in the body that leave you feeling lethargic, hungry and craving more sugar.

Eating low-GI carbohydrate foods causes a steady rise in the level of glucose in the blood, which in turn leads to a small and gentle rise in insulin. Small increases in insulin keep you feeling full and energised for hours after eating and also encourage the body to burn fat.

Foods with a GI of 70 or more are typically called 'high-GI foods' as they trigger a rapid rise in blood sugar. Foods with a GI of 55-69 are 'medium-GI foods' as they trigger a moderate increase. Foods with a GI below 55 are 'low-GI foods' because they have a minor impact on blood sugar.

 

Basic principlesnuts

  • Low-GI foods provide natural, slowly released energy.
  • Generally, the less processed a carbohydrate, the more likely it is to have a low-GI score.
  • Foods that are white, including processed foods made with white flour and white sugar, tend to have a high-GI.
  • High fibre foods take longer to digest and therefore produce a slower rise in blood sugar levels. Fibre also keeps you feeling fuller for longer, which helps prevent overeating. Most vegetables, whole-grains, legumes, nuts, seeds and fruits are rich in fibre when you eat them whole.

 

Crisp baked potatoesCombing foods with different GI scores...

Your glycaemic response to a food also depends on the other foods you eat with it. You can eat healthy high-GI foods in a meal that also contains protein and essential fats. Combining foods slows down the rate at which your body releases sugar from a meal.

For example, try a high-GI baked potato with low-fat cheese (protein) and a green salad (fibre), or a higher GI carrot soup, sprinkled with seeds (essential fats) and wholegrain pitta (fibre) stuffed with lean chicken (protein). That way you get the nutrients from healthy, high-GI foods while minimising the effect on your blood sugar.
 

Simple food swaps
 
Buy
Lower GI foods
Bin
Higher GI foods
Sugar-free muesliCornflakes
Pitta breadWhite bread
Fresh apricotsBaguettes and bagels
Under-ripe bananasApricot puree make with sugar
OatcakesOver-ripe bananas
Fruit loafCookies
Plain yogurt with fresh berriesCupcakes
SpaghettiFruit flavoured yogurts
SweetcornGnocchi
OrangeBaked potato
GrapefruitOrange squash
FructoseCanned grapefruit in syrup
New potatoesSugar
Fresh tomato salsaMashed potatoes
70% dark chocolateTomato ketchup
Tortilla wrapsChocolate biscuits


Things to watch out forBasic granary bread dough (for rolls or a large loaf)

Eating out or with friends can be difficult if you are following a low-GI diet. Limit any potential damage by remembering a few tricks. Opt for multigrain, sourdough or granary bread and say no to chunks of baguette and ciabatta. Decline chips and have an extra serving of low-GI vegetables or salad instead. Skip pudding or compromise by having a small amount. If drinking alcohol, consume with meals and try 70% cocoa chocolate to satisfy a chocolate craving or try spreading high-GI white bread with a protein-rich topping such as peanut butter to slow digestion and limit the overall effect on blood sugar levels. Added sugar affects the GI rating. This means that canned fruit in syrup has a higher GI than canned fruit in juice.

 

Moroccan chickpea soupRecipe ideas

As tropical fruits have a moderately high-GI score, try citrus, stone fruits and apples, pears, berries and rhubarb:
Apple, pear & cherry compote
10-minute winter fruit compote
Grapefruit, orange & apricot salad

 

Think bowls of steamed greens, ratatouille or veggie soups:
Spring greens with lemon dressing
Thai-style fish broth with greens
Easy ratatouille with poached eggs

Beans, beans and beans: borlotti, cannellini, kidney, black-eyed, haricot:
Italian butter beans
Braised chicken & beans
Moroccan chickpea soup

Make the most of filling lentils:
Spicy root & lentil casserole
Red lentil, chickpea & chilli soup
Easy peasy lentil curry

Try making your own wholemeal bread:
Mixed seed bread

More low-GI breakfast ideas...
More low-GI lunch ideas...
More low-GI dinner ideas...
More low-GI snack ideas...
 

Jo Lewin holds a degree in nutritional therapy and works as a community health nutritionist and private consultant. She is an accredited member of BANT, covered by the association's code of ethics and practice.

All health content on bbcgoodfood.com is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional. If you have any concerns about your general health, you should contact  your local health care provider. See our website terms and conditions for more information.

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spg1969's picture

I don't think there is any inconsistency in what she is saying about baked potatoes - they are fairly high GI and therefore in the bin section but she is saying that if you eat them with some protein and salad it will reduce the GI. Agree with pp about the fructose though, surely it is better to get used to less sweet food than replace sugar with fructose?

jagtamber's picture

i agree with first 2 comments, there are f errors on your high GI list. would be helpful if you could conduct your research before posting.

allanh's picture

To echo (and amplify) 13bridgemary's comment, the simple lists are very misleading (baked potato GOOD in your text, BAD in the table). Also, what is fructose doing in the lefthand list? Given the evidence currently being bandied about for the harm that fructose does (in fostering fat accumulation) I would have thought it was ought to have been on the 'bin' side, at least as a pure sugar. Notwithstanding your perfectly appropriate disclaimer about this being 'general information' I think you might try to avoid this kind of inconsistency.

13bridgemary's picture

Quite a lot of this is wrong.
Your 'simple food swaps' are mis-aligned.
A baked potato is low GI, not high, as is carrot soup.
Not very helpful.

babshull's picture

The best Christmas present i was ever given was a prescription to your monthly magazine (hopefully this will be my third year) it is amazing, experienced cooks and those too scared to ask "how do you do this"?
Online information in addition to the monthly magazine. (what more could you need). i will be giving this to one or two close friends this Christmas. Babs Hull

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