By Nanci Hellmich, USA TODAY
Teens, take note: Two studies out Friday look at how drinking sugary beverages impacts your weight.
One study shows that heavy adolescents who stopped guzzling sugar-sweetened drinks for a year -- not too surprisingly -- gained 4 fewer pounds than their peers who continued to drink them.
The other documents how both soda and sports drinks impact weight gain.
"We regularly see children and teens who are consuming hundreds of calories a day in sugary beverages, not just soda but energy and sports drinks, which are also loaded with calories," says David Ludwig, senior author of the new study and director of the New Balance Foundation Obesity Prevention Center at Boston Children's Hospital.
In fact, a recent government analysis showed that teens who drink soda, energy drinks and other sugary beverages are guzzling about 327 calories a day from them, which is equal to about 2½ cans of cola.
A diet high in added sugars is linked to many poor health conditions, including obesity, high blood pressure and other risk factors for heart disease and stroke. About a third of kids in the United States are overweight or obese.
To look into the impact of cutting back on liquid calories, Ludwig and colleagues recruited 224 overweight and obese adolescents, who were drinking a minimum of 12 ounces of sugar-sweetened beverages or 100% fruit juice a day.
Half were assigned to an intervention group. They were told to stop drinking sugary drinks. Non-caloric beverages (water, diet beverages) were delivered to their home for a year.
They also had check-in visits with research staff and received written messages of encouragement to stick with the program. Their parents got motivational calls to encourage the teens' adherence.
Participants in the control group were given no advice on what to drink. Everyone was tracked for a second year after the one-year intervention.
Among the findings, being published online Friday in the New England Journal of Medicine and presented at the annual meeting of the Obesity Society in San Antonio:
-- Teens in the intervention group drank almost no sugary beverages during the year-long study; those in the control group continued to drink sugary beverages, but their consumption went down moderately, possibly because of public health measures that cut down sugary drinks in Massachusetts' schools.
-- Overall, the teens who stopped drinking sugary beverages gained 4 fewer pounds in a year than teens who continued to drink them.
-- Hispanic adolescents who stopped drinking sugary drinks gained 14 fewer pounds than those who continued to drink them.
-- At the two year follow-up, there was no difference in the weight gain between the intervention and control groups.
"Soft drink consumption began to increase after the intervention was discontinued, and the difference in body weight diminished," Ludwig says. "This indicates that long-term changes in body weight will require permanent changes in sugary drink consumption.
"Reduction in sugary beverages can affect body weight quite quickly as a single behavioral change, probably more so than any other class of food products," he says.
Adolescents will readily reduce the consumption of sugary beverages if other products are conveniently available, he says.
Measures to decrease sugary beverage consumption among children may have major public health benefits, he says.
In another study, presented at the Obesity Society meeting Friday, researchers found that some teens gain a significant amount of extra weight from both sports drinks and sodas.
Alison Field, an associate professor of pediatrics at Harvard Medical School, and her colleagues examined data on almost 11,000 kids ages 9 to 15 and tracked their weight gain over time.
Findings: Teens gained almost 2 additional pounds over two years for each bottle or can of soda they drank per day. If they drank two sodas a day, they gained 4 extra pounds during that period. The adolescents put on an extra 3½ pounds for each bottle of sports drinks a day that they consumed. "It really adds up," Field says. "This is on top of what they would be gaining as part of their natural development and growth."
Sports drinks, although marketed as having 50 calories per serving, are commonly sold in 20-ounce bottles (130 calories) and 32-ounce bottles (200 calories), Field says. Individual containers and cups of soda are sold in 12-ounce cans (roughly 140 calories), 20-ounce bottles (240 calories) or even larger sizes.
"Our results suggest that adolescents drink the entire container of sports drinks and get multiple servings in that single container," she says.
Although sugar-sweetened soda is still the most popular of these sugary drinks, sports drinks, energy drinks and iced teas are gaining popularity, Field says. "Sports drinks also impact weight gain and should be limited. Parents often don't think of them as sugary beverages, but they should.
"The fact that they don't get any additional nutrition from these is why they are good area to target to control weight."
The new studies come on the heels of news that New York City is putting a 16-ounce cap on sweetened bottled drinks and fountain beverages sold at city restaurants, delis, movie theaters, sports venues and street carts.
The beverage ban, which goes into effect March 12, applies to drinks that have more than 25 calories per 8 ounces. It does not include 100% juice drinks or beverages with more than 50% milk.