Glycaemic Index

CHOICE investigates whether our national waistline can benefit from new research on the glycaemic index.
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  • Updated:2 Jun 2009

02.Can a low GI diet fight flab?

A 2007 review of the scientific evidence on GI and obesity – a Cochrane review, widely considered the gold standard – found overweight and obese adults on low-GI diets lost on average 1kg more than those on conventional weight-loss diets. Not only did they lose more weight, they also lost more body fat and had greater improvements in their cholesterol levels as a result.

Two of the studies examined didn’t control how much the dieters ate, but advised them to choose low-GI carbohydrate foods and include protein and healthy fats at each meal and snack. They were allowed to eat and snack when they were hungry – restricting kilojoule intake was not a primary concern.

The results from these studies led the authors of the Cochrane review to conclude low-GI diets work as well as or better than conventional diets even when the amount of food eaten is not restricted. Low-GI foods seem to fill you up more and satisfy you for longer.

Not all experts agree

However, while many high-profile scientists are enthusiastic about the potential for low-GI diets in weight loss, not all experts agree. Some believe the evidence still has a considerable way to go before it’s proven, citing other studies that found little or no difference in weight loss between low-GI and traditional low-fat diets.

There have been some large studies completed since the Cochrane review that didn’t find an effect, sparking further debate. And some studies suggest that any effect may be significant only in certain types of people. As ever, there are no simple answers and more research is needed to identify the real benefits, and what happens long term.

Are high GI carbs addictive?

Many people were surprised early this year to see front-page headlines in major newspapers suggesting high-GI foods may be addictive. The theory is that the intense glucose rush given by a high-GI, high-carb food may stimulate the same parts of the brain in the same way as addictive drugs. It’s an interesting hypothesis, but for now that’s all it is – a hypothesis, with some plausible explanations. More research is needed before we get too excited about it, and some of this research is about to get under way at the University of Sydney.

Low GI sugar

CSR recently introduced LoGICane – a low-GI sugar that hit the streets with much fanfare. Its GI, at 50, is in the low range, compared with regular sugar’s medium GI of 65. Low GI sounds a lot better than medium, but the difference is not huge; using less sugar overall is another strategy.

Even though the new sugar contains beneficial phytochemicals, usually removed from regular sugar, it still has the same number of kilojoules. And once you use it to cook a cake or dessert, there’s no guarantee the end result will also be low GI.

LoGICane may be a useful lower-GI swap for regular sugar if you’re trying to reduce your diet’s overall GI, but it’s not a health food. And like all sugar, it should be used in moderation.


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