US researchers have found that giving young animals diet foods can trigger obesity by encouraging overeating behaviours, suggesting that the same thing could happen to young children. Writing in the journal Obesity, University of Alberta researcher David Pierce and his colleagues have found that giving young rats the rodent equivalent of low-calorie foods affected their ability to learn how to associate the amount of energy in food with its taste. It seems that artifical sweeteners can fool the brain into assuming that all sweet things are equivalently low in calories, which can trigger over-eating when other non-diet foods are consumed. In the present experiments the age of the animals also seemed to be critical, because adolescent rats were not affected, possibly because they had already established the relationship between tastes and calories. "One thing is clear at this point," says Pierce, "our research has shown that young animals can be made to overeat when low-calorie foods and drinks are given to them on a daily basis, and this subverts their bodies' energy-balance systems." The results also fit with other recent findings including a University of Massachusetts study which showed links between diet drink consumption (amongst children) and obesity, diabetes and heart disease. "Diet foods are probably not a good idea for growing youngsters," Pierce cautions.