April 2 (HealthDay News) -- When it comes to losing weight, cutting back on the calories in sugar-sweetened drinks, rather than food, may be most important.
So say researchers who found that cutting back on calories from sugary beverages -- by only one serving per day -- accounted for nearly two-and-a-half pounds of lost weight over 18 months.
"Weight loss from liquid calories is greater than loss of calorie intake from solid food," concluded lead researcher Dr. Liwei Chen, an assistant professor of epidemiology at the School of Public Health at the LSU Health Science Center in New Orleans.
One reason for this is that the body is able to self-regulate its intake of solid food. For example, if you eat too much solid food at lunch, you'll tend to eat less at dinner. But the same self-regulation is not there for what you drink, experts say. Your body does not adjust to liquid calories, so over time, you gain more weight, Chen explained.
"If you reduce your intake of beverages, particularly sugar-containing beverages, it's a simple but easy way to help you maintain your weight," Chen said. "You can avoid additional weight gain, or if you are on a diet, it's an easy, simple way to help you achieve your goals," Chen added.
One dietitian said the finding wasn't so surprising.
The study "supports what many have suspected -- liquid calories don't satisfy," said Connie Diekman, director of university nutrition at Washington University in St. Louis. "In addition, the identification that [sugar-sweetened beverages] can impact weight gain more than other liquids is an important message as Americans continue to work to lower their calories."
And if you get thirsty? "Drink water," Chen said.
The report was published in the April 1 issue of the American Journal of Clinical Nutrition.
For the study, researchers studied the diets of 810 adults 25 to 79 years old who participated in the Lifestyle Interventions for Blood Pressure Control (PREMIER) trial. People in the trial, which lasted 18 months, were randomly assigned to one of three groups: advice about lowering blood pressure; lifestyle intervention (including dieting advice and exercise to lower blood pressure); or lifestyle intervention plus a specific diet that was rich in fruits and vegetables.
In the current study, researchers specifically looked at the weight of the participants and the beverages they drank. People in PREMIER had their weight measured at six and 18 months and were quizzed about their diet by unannounced phone interviews.
Beverages were placed into seven categories: sugar-sweetened beverages (including soft drinks, fruit drinks, fruit punch, or high-calorie beverages sweetened with sugar); diet drinks such as diet soda and other diet drinks that were artificially sweetened; milk (including whole milk, 2 percent milk, 1 percent and skim); 100 percent fruit and vegetable juice; coffee and tea with sugar; coffee and tea without sugar; alcoholic beverages.
The researchers found that sugar-sweetened drinks accounted for 37 percent of all the liquid calories people in the study consumed. Among beverages, sugar-sweetened beverages were the only type of beverage type significantly associated with weight change at both the 6 and 18 months, the researchers noted.
Drinking fewer sugary drinks was more important than eating less for losing weight, the researchers found. In fact, drinking one less serving of a soft drink was associated with just over one pound of weight loss at six months and an additional weight loss of more than 1.4 pounds at 18 months.
Diekman said the findings are a reminder that little things mean a lot when it comes to weight loss.
"If one small diet change can trigger a one-half- to one-pound weight loss in six months, adding other small changes or boosting activity even 15 minutes a day could make 'healthy' more attainable," she said. "As a registered dietitian, this study indicates to me that helping people make gradual changes will help them comfortably achieve a healthier weight."
Consuming liquid calories has increased along with the obesity epidemic, Chen's group noted. In earlier studies, researchers found that 75 percent of U.S. adults could be overweight or obese by 2015, and they tied drinking sugar-sweetened beverages to the obesity epidemic.
In 2006, the nation's major soft drink companies agreed to limit the sale of sodas in U.S. schools. That deal was brokered by the Alliance for a Healthier Generation, a joint effort of the American Heart Association and the President William J. Clinton Foundation.
SOURCES: Liwei Chen, M.D., Ph.D., M.H.S., assistant professor of epidemiology, School of Public Health, LSU Health Science Center, New Orleans; Connie Diekman, M.Ed, R.D., director, University Nutrition, Washington University, St Louis; April 1, 2009, American Journal of Clinical Nutrition