This has certainly been the decade of jumping the sugar ship – and largely with good reason. The studies to illustrate what excess sugar can do to the body keep rolling in. And a new one in the journal Obesity goes a little further by trying to tease apart the difference between cutting out sugar and losing weight. It argues that sugar isn’t bad because it makes you gain weight. It’s bad because it brings about other, more sinister changes to the body – metabolic changes that are distinct from weight. Though this may be true, in part, weight certainly plays a role. So for the purposes of most of us, there may not be much reason to split hairs, since the takeaway hasn’t changed: Sugar is bad for us for multiple reasons, and cutting down on it is usually a good thing.

“This study definitively shows that sugar is metabolically harmful not because of its calories or its effects on weight; rather sugar is metabolically harmful because it’s sugar,” said study author Robert Lustig. “This internally controlled intervention study is a solid indication that sugar contributes to metabolic syndrome, and is the strongest evidence to date that the negative effects of sugar are not because of calories or obesity.”

The researchers studied the effects of sugar-restriction on 43 obese children, aged nine to 18, who had at least one other metabolic problem, like high blood pressure or high triglycerides (blood fats) or markers of fatty liver. For nine days, they ate a sugar-restricted diet, but their calories were kept as constant as possible, by substituting in starches and carbs for the sugars. The goal was to reduce sugar content in the diet from an average of 28% to 10%. But the team did not want the kids to lose weight – they wanted to keep weight constant while simply subtracting sugar from the diet, so see what would happen when this variable to changed but nothing else was.

At the end of the nine days, the kids’ metabolic parameters did shift significantly: Their average diastolic blood pressure decreased by 5 mmHg; their triglycerides were lowered by 33 points; their LDL (“bad”) cholesterol went down 10 points; insulin levels were reduced by a third, and fasting glucose and liver function tests improved.

“All of the surrogate measures of metabolic health got better, just by substituting starch for sugar in their processed food – all without changing calories or weight or exercise,” said Lustig. “This study demonstrates that ‘a calorie is not a calorie.’ Where those calories come from determines where in the body they go. Sugar calories are the worst, because they turn to fat in the liver, driving insulin resistance, and driving risk for diabetes, heart, and liver disease. This has enormous implications for the food industry, chronic disease, and health care costs.”