Almost any bodybuilder worth his biceps can tell you that fat loss requires cutting back on fruit. This is partly because fruits contain carbs, but it’s also because they contain a lot of the sugar fructose. Bodybuilders have long feared fructose, because it’s different from other sugars. Instead of being sent to muscle tissue, fructose has to go to the liver first, and if the liver is already full of stored carbs (in the form of glycogen) it converts the fructose into fat.

A newly published study from the University of California (Davis) indicates that fructose is even scarier than previously thought. Researchers had subjects eat a standardized diet, but fed them beverages sweetened either with glucose or fructose. After 10 weeks, both groups had gained weight, but the subjects in the fructose group experienced a slew of other negative effects. Most dramatic was that fructose changed the way their bodies metabolized dietary fat, encouraging the creation of new fat cells around vital organs, such as their hearts and livers. They also experienced a reduction in insulin sensitivity, which is linked to diabetes and can decrease fat burning and impair muscle growth.

For all these reasons, we recommend limiting fructose intake. To do this, avoid foods sweetened with fructose or high-fructose corn syrup. Also put a limit on fruit. We’re not saying to avoid it completely, as fruit has benefits, such as phytonutrients that aifat loss and muscle growth, but keep your intake to about two or three servings per day and plan well, choosing morning and before workouts for your fruit feast.