Do low-calorie sweeteners cause weight gain? This seems to be the burning question these days, and one the media appears completely dazzled by. A close look at the clinical research, however, reveals the reality - low-calorie sweeteners are helpful, not harmful, in weight loss and weight management efforts. If you consider the way we gain weight - when calories in exceed calories out - replacing the calories from a sugary, high calorie food with a low-calorie sweetened food should help with the weight loss side of the equation. “The claim that low-calorie sweeteners cause weight gain is based on a few studies that have been met with significant criticism from nutrition experts. The studies in question contradict years of human clinical studies - and practical experience - that show low-calorie sweeteners are useful in facilitating weight loss,” explains Jennie McCary, MS, RD, LD, a registered dietitian and spokesperson for the New Mexico Dietetic Association.