Cutting back on sugary calories could make you gain weight instead of lose it, a study suggests. Scientists at Purdue University compared rats fed either zero-calorie saccharin or sugar, and found that those on artificial sweetener gained more weight—mostly in fat, Time reports. Animals appear conditioned to respond to sugar by eating less; when they don't taste it, they eat more.
There's more: Sugar jump-starts the metabolism to ready the body for more calories. Substitutes don’t, so the system remains sluggish, storing incoming calories as fat. While the findings don't extend to people yet, past studies on humans echo these ideas. If they pan out, it could leave dieters weighing the threat of fat versus that of sugar’s known risks, like diabetes.