The glycaemic index (GI) is a measure of the extent to which a food raises blood sugar. Generally speaking, the higher the GI, the unhealthier the food is. Lots of sugar generally means lots of insulin ” and excess of which can promote of a slew of unhealthy biochemical processes including increased fat-making and reduced fat mobilisation (and hence weight gain) within the body, and a raised risk of ‘insulin resistance’ which can ultimately lead to type 2 diabetes (see Wednesday’s post for more on this).
Some doubt the usefulness of the GI in nutritional management, but I for a long time have thought it is actually quite a graphic measure of the likely health effects a food will have. In the GI scale, glucose (pure and very fast releasing sugar) is assigned a value of 100. Very few will not understand the implications of eating wodges of French bread, wholemeal bread or fist-sized baked potatoes when they see that the GIs of these foods are about 95, 70 and 85 respectively. Most individuals will immediately recognise the wisdom in cutting back on these foods.
The potential benefits of eating a low-GI diet were tested recently by French researchers . In this study, 38 individuals were randomly assigned to eat a diet where the starch in the diet was either of a low GI or high GI nature. The individuals were not instructed to limit how much they ate. The trial lasted for just 5 weeks.
Despite the short duration of the trial, the group eating the low GI starch lost significantly more weight than the high GI starch consumers (1.1 kg on average compared to 0.3 kg). They also saw significant improvements in their cholesterol level (an average drop of almost 10 per cent) as well as the ratio of total cholesterol to ‘healthy’ HDL cholesterol. Both these changes would generally be viewed as a sign of reduced risk of cardiovascular disease. In comparison, the high GI eating group did not see these benefits.
The trial did not find that eating the lower GI diet improved the effectiveness of insulin (insulin sensitivity) compared to the higher GI diet. However, insulin sensitivity generally takes quite a while to change, and 5 weeks is probably not long enough for benefit to be seen in this particular parameter.
The authors of the study concluded that: Lowering the GI of daily meals with simple dietary recommendations results in increased weight loss and improved lipid profile and is relatively easy to implement with few constraints. These potential benefits of consuming a LGI (low glycaemic index) diet can be useful to develop practical dietetic advice.�
The results of this study mirror my own experience in practice: that it is possible to get benefits from dietary change that focuses not on the calorific value of the foods that people eat, but the form than these calories come in. Such an approach often liberates individuals from feelings of hunger and sacrifice that so often comes as part and parcel of conventional ‘diets’, and makes their new regime much more sustainable. I have seen countless individuals make what look like permanent positive shifts in their eating habits by embracing this sort of approach. On the other hand, I’ve know very few who have managed to ‘last’ on a diet that explicitly restricts food in terms of calorie content and therefore leaves them hungry. Quality, not quantity, is the key.
1. de Rougemont A, et al. Beneficial effects of a 5-week low-glycaemic index regimen on weight control and cardiovascular risk factors in overweight non-diabetic subjects. British Journal of Nutrition 2007;98(06):1288-1298
I HEAR CONFLICTING REPORTS ON THE VALUE OF THE LOW GI DIET. 30 YEARS AGO I WAS ON A CARB FREE DIET OF ONLY FRESH FOODS WITH LOTS OF GREEN VEG. AND LOST A LOT OF WEIGHT- 20 LBS. IN 2 MONTHS. I FELT WONDERFUL, ENERGETIC AND LIGHT IN MOVEMENT. BUT I HAD TO EAT MORE BECAUSE I KEPT LOSING WEIGHT TO 105 LBS. I AM TRYING TO EAT NOW SOMEWHAT LIKE THAT AGAIN. WILL SEE WHAT HAPPENS. GOOD TO READ REPORTS THAT HELP REINFORCE THE WILL TO DO RIGHT IN EATING. THANK YOU.
Yes, I agree about low GI etc. However some foods being high in fat have a lower GI than expected as the fat slows the rate of absorption in the system. For example Mars bars are awful but not as high GI as expected becayse of this. Similarly carrots (very good) whivch appear to have ahigh GI are an exellent food. Along with GI you need to make it clear that lowish junk food GI is not good.
lucille you say “30 YEARS AGO I WAS ON A CARB FREE DIET OF ONLY FRESH FOODS WITH LOTS OF GREEN VEG. ” actually you were on a low carb diet not a carb free diet. A carb free diet would have no carbs whatsoever & all you would be eating would be protein & fats, which by the way is not necessarily a bad thing, just a bit boring I suppose as we are used to a variety of tastes & textures in our diets now. I think most people are confused by the strange reports we see in the media about the myth of having to eat grains & lots of them. Of course the only beneficiaries of that sort of diet are the people who grow them & those who make “foods” out of them not hard to see why the push it so much. Nothing to do with health all to do with making money! Really there is no need to even think about low GI or low GL just don’t eat starchy foods (mostly white coloured things) or anything that comes in a packet of any type & it really is easy – real food, meat & high nutrient content vegies & fruit ( none of the high sugar ones ) & some dairy like butter, cream & you can’t go wrong really.
I do find all this talk about low GI very odd when you consider the Japanese are one of the largest consumers of rice (high GI):
Longest lifespan – Japanese
Quality of life – high (ie they do not live a long time while at the same time being ill)
QED – high GI cannot be bad for you.
Health and longevity are influenced by a multitude of factors, of which dietary GI is just one. It is simply incorrect (from a scientific perspective) to conclude from the Japanese experience that high GI diets are not harmful to health.
There is now abundant evidence which supports the notion that high GI/GL/carb diets can be detrimental to health. By way of example, the post that precedes this one looks at recent evidence which links high GI/GL food consumption and an increased risk of diabetes. Rice, as it happens, appeared to be a particular offender. Do please have a read (if you haven’t already).
Just wanted to let you know about a website I have put together. Has over 500 GI recipes and a database of GI foods.
Cheap to join (only £1) and was inspired by my wife who has PCOS.
I’m still not familiar with this low GI diet, but soon I’d probably try minimizing the intake of starchy foods such as rice. This article would really help those who are trying to follow a dietary routine…I once came upon a website which also deals on having a healthy diet http://www.completedietinfo.com/ I think you might also be interested in it.
Personally I have found the low GI diet to be really successful, its easy to follow and the values all make sense to be. I’ve lost a stone so far which is the most I have lost on any diet to date..And trust me there have been many! Great article!
I think it’s important to apply a bit of common sense. To try to avoid most food with high GI (I don’t avoid to eat bananas, carrots or peas, now and then), but as well, try to avoid or reduce others that are “allowed” but they are very rich in fat. Try to get healthy options.