In randomized controlled trials—experiments in which one group of people is fed artificial sweeteners and another group is not—it usually, but not always, looks as if artificial sweeteners may help people lose a tiny amount of weight. But when scientists observe people in the real world over long periods of time who use artificial sweeteners versus those who do not, they find that those who consume artificial sweeteners are at higher risk for weight gain, heart disease, metabolic syndrome, and diabetes.
