Deciphering the Findings
"There were huge differences in four-year weight gains based on what people did," he says. "The quantity of fat in the food didn't seem to be strongly related to weight gain." For instance, no differences were seen for low-fat or skim milk compared to whole-fat milk.
Rather, he says, focusing on the quality of food -- not simply total calories, or fat grams, or grams of carbohydrates -- seems most important in avoiding weight gain.
They write: "A habitual energy imbalance of about 50 to 100 kilocalories per day may be sufficient to cause the gradual weight gain seen in most persons."
Yogurt was perhaps the biggest surprise on the list of foods linked with less weight gain, Mozaffarian says. The researchers aren't sure why. They cite some other research finding that changes in gut bacteria from eating yogurt may help in weight control. Or those who eat yogurt may have other healthy habits.
Changes in diet had the strongest link to weight gain. However, the researchers also found that those who slept 6 to 8 hours a night gained less than those who slept less than 6 or more than 8. Weight gain was also linked with changes in the amount of television viewing and changes in physical activity.
''Small differences add up over time," Mozaffarian says. He sees that as both ''a danger and an opportunity." If you don't pay attention, he says, the pounds can pile on quickly. "If you do pay attention, a handful of changes could add up in a beneficial way," he says.
He is not suggesting people completely avoid foods linked with weight gain. "If someone wants to eat some of the foods on the list associated with weight gain, as long as they eat a lot of other foods that are not associated with weight gain, and exercise, and not watch a lot of TV, that would be OK," he says.
Mozaffarian reports receiving honoraria from Unilever, Aramark, and other food-related companies for speaking on diet-related topics.
Avoiding Weight Gain With Age: Perspective
The study provides some good support for factors other experts have assumed are linked with weight gain, says Connie Diekman, RD, director of university nutrition at Washington University in St. Louis. She reviewed the study but was not involved in it.