A sugar rich diet may raise your risk of dying of heart disease even if you are not overweight. Says a major study published in JAMA Internal Medicine Over the course of the 15-year study, participants who took in 25% or more of their daily calories as sugar were more than twice as likely to die from heart disease as those whose diets included less than 10% added sugar. Overall, the odds of dying from heart disease rose in tandem with the percentage of sugar in the diet—and that was true regardless of a person’s age, sex, physical activity level, and body-mass index (a measure of weight).

Nutritionists frown on added sugar for two reasons. One is its well-known links to weight gain and cavities. The other is that sugar delivers “empty calories” — calories unaccompanied by fiber, vitamins, minerals, and other nutrients. In this study, the researchers measured the participants’ Healthy Eating Index. This shows how well their diets match up to federal dietary guidelines. “Regardless of their Healthy Eating Index scores, people who ate more sugar still had higher cardiovascular mortality,” says Dr. Teresa Fung, Adjunct Professor of Nutrition at the Harvard School of Public Health.

Exactly how excess sugar might harm the heart is not clear. Earlier research has shown that drinking sugar-sweetened beverages can raise blood pressure. A high-sugar diet may also stimulate the liver to dump more harmful fats into the bloodstream. Both factors are known to boost heart disease risk.