Sugar-sweetened beverages and even one hundred percent fruit juices were also associated with weight gain.

Laura Jeffers, a registered dietitian at Cleveland Clinic, did not take part in the study but believes it confirms what dieticians and nurtritionists have known for years about sweetened drinks:

“I basically always talk to patients about can we reduce the calories you’re getting from beverages? That’s one of the easiest things to do and this research shows that sugary beverages contribute to weight gain,” she said.

But the study findings also run counter to conventional wisdom. Several high-calorie foods were found to lead to less weight gain when their consumption was increased. In particular nuts, whole grains, yogurt, fruits, and vegetables, were all associated with less weight gain over time.

The study also found that lifestyle factors such as daily physical activity, exercise, and sleep patterns are also important variables in any weight management program.

“The dangers are that if you don’t pay attention to these small aspects of lifestyle you may gain weight...and slowly, over time, and not notice it. And that is what we have seen in the obesity epidemic. On the other hand, if you pay attention and focus on the appropriate aspects of lifestyle you won’t gain that weight over time," Mozaffarian said.

The study showed that together with certain foods, long periods of television-watching and chronically getting too little sleep also contributed to long-term weight gain.