Wednesday, January 28, 2009

Sweeteners and your waist

They are called non-nutritive sweeteners (NNS) or intense sweeteners, although you and others probably still call them artificial sweeteners. Some of you will recall Tab and Tresca, soft drinks from the 1970s with saccharin or cyclamate in them. You only drank them as a form of punishment or if you had diabetes and were told to stick to sugar-free drinks.

Diet revolution of the 1980s
In 1985 aspartame (or Nutrasweet) was approved for use in Australia and the diet drinks tasted a whole lot better, as did other foods in which a sweetener replaced sugar. This was a time when sugar was listed under “Evil” in encyclopaedias (along with Hitler, nuclear bombs and disco music). Many people chose to drink diet drinks and anything hinting at no-added-sugar because this was seen as a sensible way to eat less kilojoules and remain lean.

A US survey in 1986 showed that those consuming the NNS were a wee bit chubbier than those that didn’t, speculating that NNS caused weight gain. Of course, you all know that surveys can only show associations and not cause and effect. When the survey was looked at again then it was equally likely that chubby people consumed more diet products because they wanted to get leaner. Since then, there has been little evidence that eating NNS causes weight gain or even helps much in weight loss.

Diet food compensation
A review of the evidence did suggest that NNS consumers may eat fewer kilojoules. One theory to explain this is that NNS trick the brain into thinking it has had food and shouldn’t feel as hungry, thereby leading to less food being eaten. People ate around 5-15% fewer kilojoules with diet products under test conditions, but there is little support that NNS use helps with weight control in free-living humans. One reason is that some people use diet products as a compensatory mechanism to offset a high fat food they may have eaten, so it’s no surprise if they don’t lose weight.

What does it all mean?
There is no compelling evidence that NNS themselves help people lose weight or maintain a healthy weight. Although a diet drink, for example, substituted for a regular sugared drink may be helpful to the weight conscious, the best advice we can give in the foreseeable future is: eat well, don’t eat too much, be active and ignore diet advice given on daytime TV (see non-story below).

Reference: American Journal of Clinical Nutrition 2008; 89: 1-14

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