Low-calorie sweeteners could be making us fatter, a study has suggested. Researchers said one possible explanation is that the sugar substitute is affecting our metabolism, triggering it to lay down more abdominal fat. Dr Chee Chia, who co-authored the study, has warned that rather than helping us keep the pounds down it could in fact be contributing to the obesity epidemic. She said, “This is a cause of concern and has important public health implications. We really need to do more work to look at what is going on.” The study looked at the body measurements and diets of 1,454 men and woman in the US between 1984 and 2012, comparing those who used low-calorie sweeteners with those who didn’t. It found that 10 years on, those who did use the sugar alternative had a 2.6cm larger waist circumference and were 37 more likely to have abdominal obesity. Dr Chia said one possible explanation could be that low-calorie sweeteners trigger the body to lay down more abdominal fat – though more research was needed to establish the link. The study concluded, “Low-calorie sweetener use is independently associated with heavier relative weight, a larger waist and a higher prevalence and incidence of abdominal obesity, suggesting that low-calorie sweetener use may not be an effective means of weight control.” The study said that worldwide obesity levels had not slowed for the past three decades, with one billion adults projected to have obesity by 2025. Despite low-calorie sweeteners long recommended for those dieting, it said the sugar alternative’s effectiveness ‘faced increasing scrutiny and remained controversial’. It added that the results of research so far had been inconsistent. The International Sweeteners Association said the study was observational and could not prove cause and effect. Having come in for criticism over their contribution to increasing levels of obesity, members of the food and drink industry have launched several sugar-free items that use low-calorie sweeteners.