Glycemic Index Myth
by Christian Finn, http://www.thefactsaboutfitness.com
The annual appearance of the glycemic index (the GI for short) in the Sunday Times as the "easy, healthy way to permanent weight loss," has become something of a tradition here in the UK. This year, however, they've taken it to a "whole new level," claiming that it can help you look younger and lower your stress levels.
Editor's note: I came across this article, and was impressed with how it put GI in perspective. Proper attention to GI does provide benefits, such as reduced hunger and a better hormonal balance. But there is no getting past the basic formula of calories in - calories out. Finn explains the implications very well.
Despite its popularity, eating more carbohydrate-rich foods with a low GI and fewer carbohydrate-rich foods with a high GI — without making any other change to your diet — actually has very little effect on weight loss.
I'll explain why in a moment. First, just in case you've never heard of the glycemic index, here's a quick primer:
The glycemic index is a tool used to rank different types of food according to the effect they have on blood sugar levels. Foods that lead to a rapid rise in blood sugar levels are known as high glycemic index foods. Foods that lead to a slower rise in blood sugar levels are said to have a low glycemic index.
While the glycemic index tells you how rapidly a food raises blood sugar, it doesn't tell you how much carbohydrate is in that food. To understand how the food will affect blood sugar levels, you need to know both. That's where the glycemic load helps.
The glycemic load takes the glycemic index into account, but gives a more complete picture than the glycemic index alone. The carbohydrate in a carrot, for example, has a moderate glycemic index. But there isn't a lot of it, so the glycemic load of a carrot is actually quite low.
When I first read about the glycemic index in the early 1990's, it seemed to make perfect sense. And, being one of those people who have a tendency to obsess over small details, I invested a lot of time and effort in eliminating foods with a high GI from my diet.
Much of this effort, unfortunately, was a complete waste of time.
It's not that there's anything wrong with following a diet that has a low GI. However — if you make the same mistake that I did — and focus only on the glycemic index (without making a change to your calorie intake too), chances are you'll end up feeling frustrated because you're not losing any weight.
In one of the most recent studies of the glycemic index, researchers from the University of Minnesota tested whether lowering the GI of a diet already low in calories would have any further effect on weight loss.
The researchers compared the effects of three low-calorie diets, each with a different glycemic load, on 29 obese adults. All of the diets — high GI, low GI or high fat — provided the same number of calories.
For the first 12 weeks, all food was provided to the subjects (the feeding phase). Then, 22 subjects were told to follow the assigned diet for an additional 24 weeks (the free-living phase).
After 12 weeks, all three groups lost weight. However, there was no significant difference in weight loss between the groups. Subjects on the low GI diet lost, on average, 21.8 pounds (9.9 kilograms), while those on the high GI diet lost 20.5 pounds (9.3 kilograms).
"In summary, lowering the glycemic load and glycemic index of weight reduction diets does not provide any added benefit to energy restriction in promoting weight loss in obese subjects," conclude the researchers.
Eating a diet with a low glycemic load can help with weight loss. But, that's largely because many foods with a low glycemic index (with the exception of high-fat foods like nuts and avocados) also have a lower energy density.
Most fruits and vegetables, for example, have a low glycemic load. So, when you eat fewer foods with a high glycemic load (e.g. cookies, cakes, or sweets) and more foods with a low glycemic load (e.g. fruits and vegetables), you end up eating fewer calories. The result is that you lose weight.
Maybe I'm mistaken, but I think most people realize that eating cakes and cookies isn't going to help them lose weight. And while some of the recipes in GI diet books are useful, they're not always very practical.
Single people like me, for example, who are either too busy, too lazy or too stupid to cook (I'm a little embarrassed to admit it wasn't until I was 31 that I discovered what "sautéing" meant) usually want something that doesn't involve spending hours cooking and cleaning in the kitchen .
Although its frequent appearance in newspapers and magazines means that the glycemic index (along with companion tools such as the insulin index) will remain popular, it's my opinion that it adds an unnecessary layer of complication to what is a relatively simple (though not always easy) process.
Christian Finn is the main brain behind http://www.thefactsaboutfitness.com, which offers a free newsletter to those interested in accurate information about fitness.
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