Artificial sweeteners are taken every day by more than half the adult population of America as a supposedly healthier option to sugar. But the products do little to help them lose weight - and may even cause them to put more weight on, a new study has discovered.
Low-calorie sweeteners may increase our desire for sweet foods, which, in turn, cause weight gain. Scientists have discovered that the artificial substitutes cause a disassociation in the brain between energy and sweetness, and disrupt its ability to accurately assess the calories we're consuming.
In one study, researchers found that sugar can stimulate the areas of the brain related to expectation and satisfaction, so switching off the desire for more sweetness. Using brain imaging, they discovered that artificial sweeteners were not activating the same neural pathways.
The statistics seem to bear out the theory. In 1987 around 70 million Americans were taking sweeteners, and this grew to 160 million by 2000. Over the same period, obesity levels rose from 15 per cent to 30 per cent.
(Source: Neuroimage, 2008; 39: 1559-69).