Maybe the world seems a bit upside down already, but when it's discovered that diet coke makes you put on weight, we seriously need a reality check. It has been found by researchers at Purdue University in Indiana, USA, that artificial sweeteners can actually cause the body to gain weight rather than aid it to lose weight.

Researchers Susan Swithers and Terry Davidson fed 27 rats with either real glucose or saccharin to monitor any changes in weight.

Their findings reveal that the super-sweet taste of saccharin, which is usually 200 times sweeter than natural sugar, alerts the body that a large amount of calories are about to be consumed, so the digestive system goes into overdrive in preparation for this large intake. When they don't arrive, it gets confused.

Swithers and Davidson concluded that "this interference could lead to reduced energy utilisation and, ultimately, to increased weight gain."

Although, this research isn't too new. When sweeteners were first gaining ground in the 1980s, doctors and scientists warned that they could lead to increased weight gain. The reason being that any sweet taste makes the body crave more, so typical consumers of saccharin are likely to consume more carbohydrates and calories in general.

Also, after a satisfying meal, serotonin levels in the brain increase, which in turn gives rise to a contended feeling. However, aspartame which is one of the main saccharines used in diet-foods halts the production of serotonin, so that feeling of relaxation and contentment never materialises and we reach for more food to compensate.

For example, having a diet soft drink sort of "allows" us to eat more, because we know we haven't consumed the calories in the drink. Jean Weininger from the San Francisco Chronicle said, "people who use artificial sweeteners don't necessarily reduce their consumption of sugar -- or their total calorie intake. Having a diet soda makes it okay to eat a double cheeseburger and a chocolate mousse pie"

However, it can be said that this trial was slightly restrictive if it was attempting to mirror the human diet. Swithers and Davidson conceded that "the generality of findings obtained with rats in the laboratory to humans in their much more complex food environments can and should be questioned."