The DRINK trial answered that question in 2012.
Researchers randomly assigned 641 mostly normal-weight Dutch children who usually drank sugary beverages to get a daily 8 oz. drink sweetened with either sugar (104 calories) or artificial sweeteners (0 calories) at school each day. Neither the children nor the investigators knew who got which drinks.
“The question was whether the children who got zero calories would sense the difference and compensate by eating more calories from some other source,” says Katan. “Would those kids come home and say, ‘Mom, I’m hungry. I want a snack,’ or would they just have their usual lunch and dinner?”
What the DRINK trial found
After 1½ years, the average child who got the sugary drinks had gained roughly two pounds more than the average child who got the sugar-free drinks. And the chubbier kids gained about three pounds more if they got their usual sugary drinks.
“Even the thinnest children were not immune to the effect of sugary drinks,” says Katan. “But heavier kids may be less likely to sense when they’re eating fewer calories and when they’re overeating.”
More evidence that some people are more vulnerable than others: an observational study published on the same day as the DRINK trial that tracked roughly 11,000 nurses and health professionals for 12 to 18 years.
Among men and women with a genetic risk of obesity, those who drank at least one sugary drink a day were four times more likely to become obese than those who drank less than one sugary drink a month.
The bottom line
“Sugary drinks make you fat. They circumvent your innate mechanisms for keeping your body weight stable,” says Katan.
“If you eat beans or whole wheat bread, they’re not fattening because you feel full, so you don’t eat other things.”
In contrast, “if you drink sugary drinks, including fruit juices—there’s no difference between fruit juices and soda—they will simply slip in through the back door and you’ll just keep eating as much as you usually do.
“They’re burglars who will rob you of your leanness because you don’t notice them coming in.”