Artificial sweeteners may cause weight gain

The study, published in the latest Behavioral Neuroscience, was carried out by Drs Susan Swithers and Terry Davidson, two psychologists based at the Ingestive Behavior Research Center at Purdue University, West Lafayette, Indiana.

The idea is that the sweet taste leads the body to expect a certain level of energy intake, and that eating something sweet that has no caloric value leads to an inbalance between energy intake and expenditure.

The research was carried out on rats, who were split into two groups: one that was given yogurt sweetened with glucose and one that was given yogurt sweetened with zero kilojoule saccharine. The rats that ate the saccharine-sweetened yogurt ate more kilojoules, put on more weight, gained more body fat and did not cut back their kilojoule consumption over time.

This may offer some explanation of why the obesity epidemic has increased at the same time as consumption of artificial sweeteners and why research on the use of artificial sweeteners and weight gain is equivocal - some research suggests that their use leads to weight loss, others to weight gain. Furthermore, the rats fed the artificial sweetners did not raise their body temperature as much as those fed glucose - a response to the anticipation of high kilojoule intake. This may be why the rats gained weight - the temperature response allows mammals to burn kilojoules.

This research comes as there is increasing evidence that people who consume low-kilojoule, artificially sweetened soft drinks are at high risk of developing obesity and metabolic syndrome.