New research helps explain why sugary drinks are under such heavy attack in the fight against obesity. NBC's Robert Bazell reports.
Good news for parents worried about their kids’ weight – it’s possible to get them to stop drinking sugary drinks, and the kids gain less weight when they stop. The bad news is it takes a lot of work.
Two studies published Friday show that kids will stop drinking full-sugar sodas, juices and sports drinks if they have something else handy and if they are encouraged and rewarded for doing so. In one study, the kids actually lowered their body fat and in both studies the kids who got diet drinks or water gained less weight than children allowed to continue their usual habits.
The studies demonstrate that it is possible to fight back against childhood obesity, but it will take a lot of vigilance. They may also vindicate a recent, controversial decision by New York to ban the sale of supersized drinks that are sweetened with sugar.
In one, Cara Ebbeling, Dr. David Ludwig and colleagues at Boston Children's Hospital worked with 224 overweight or obese 9th and 10th graders who said they regularly drank sugary beverages. They divided the group into half, and made it easy for half the kids to ditch the junk drinks. They delivered water and diet drinks to the homes every two weeks for a year, called the parents each month and had three in-person visits with the kids. They also sent reminders in the mail, and sent gift cards to supermarkets.
Providing water and diet drinks “virtually eliminated” drinking of sugary sodas and juices, the researchers report in the New England Journal of Medicine.
At the start, the kids drank on average nearly two sugary drinks a day – sodas, full-sugar fruit juices, sports drinks and so on. The group that got the sugar-free drinks and water, plus counseling and reminders, virtually stopped drinking sugary drinks at all. After a year, they also weighed less – four pounds less on average than the kids in the “control” group who kept on with their soda habit.
The effect on Hispanic kids was astounding. They gained 14 fewer pounds than the control group.
"No other single food product has been shown to change body weight by this amount over a year simply through its reduction," says Ludwig.
However, after two years, the benefits stopped – the kids given sugar-free drinks went back to their bad old habits and everyone ended up with the same amount of body fat, on average.
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Two studies show that kids who swap sugary drinks for water or diet drinks gain less weight.
A second study, done in the Netherlands, had similar findings. Janne de Ruyter of the VU University Amsterdam and colleagues studied 641 normal-weight children aged 4-12. The children were randomly assigned to get either 8 ounces of artificially sweetened beverage or 8 ounces of sugar-sweetened drink delivering 104 calories for 18 months.
“We developed custom drinks for this study to ensure that the sugar-free and sugar-containing drinks tasted and looked essentially the same,” De Ruyter’s team wrote. As in Boston, the kids were regularly encouraged to drink the beverages they were given.
“Children were eligible only if they commonly drank sugar-sweetened beverages, because we considered it unethical to provide sugary beverages to children who did not habitually consume such beverages,” they added.
After 18 months, the kids all grew, of course, but the kids who got the diet drinks gained less weight—about two pounds less after 18 months. “The sugar-free group gained significantly less body fat,” De Ruyter’s team added. “Children in the sugar-free group who completed the study gained 35 percent less body fat than those in the sugar group.”
The children who got the sugar also grew very slightly taller. “Although the difference in height gain was minute, it warrants scrutiny,” they wrote, noting that some studies suggest that obese children prepuberty grow taller than non-obese children. They predict the affect will wear off by adulthood.
Again, the experiment wasn’t easy. The kids required constant reminders and 164 of the kids stopped drinking the drinks, most because they didn’t like them.
Their findings contradict studies that suggest drinking diet drinks can also cause weight gain, because the body senses the sweet taste, wants more calories, and gets them elsewhere – either through hunger or by extracting more calories from food. They also start to answer questions about where our obesity epidemic comes from – sugary drinks, junk food, too little exercise or a combination, says Dr. Andrew Racine, a pediatrician and also an economist Montefiore Medical Center in the Bronx. But he says, they don’t offer a prescription for fighting the problem. “Nobody could take one of these studies and replicate it on a population level,” he says.
Dr. Sonia Caprio, a pediatrician at Yale University, points out that sugar-sweetened drinks make up 15 percent of calories for some Americans, with adolescent boys drinking an average of 357 calories a day. “Sugar-sweetened beverages are marketed extensively to children and adolescents, and large increases in consumption of sugar-sweetened beverages have occurred among black and Mexican-American youth, who are known to be at higher risk for obesity and the development of type 2 diabetes than their white counterparts,” she wrote in a commentary on the studies.
“Taken together, these ... studies suggest that calories from sugar-sweetened beverages do matter,” she wrote.
Racine agrees there and he approves of New York’s decision to ban the sale of the largest sweet drinks at restaurants, delis and movie theaters, calling it a social experiment.
“It will be possible to look at the policy and compare New York to other cities,” he said. He likens it to the beginning of the battle to reduce smoking, and says it will take many approaches together to help get people to drink less sugar – publicizing research that demonstrates the harm, taxing harmful products, making it harder to get them, and, eventually, social disapproval.
The beverage industry has fought hard against any suggestion that sugary drinks underlie the obesity epidemic, while also working with schools to replace full-sugar sodas in school vending machines with water and diet drinks. Racine said their actions show they fear public policy can affect soda consumption. "If they didn’t believe this was going to have a potentially important impact .. they wouldn’t be worried about it," he says.
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