Sugary Drinks & Weight Gain: New Evidence

With policies like the recent portion-size cap adopted in New York City, it’s evident that many blame sugar-sweetened beverages, at least in part, for contributing to the obesity epidemic. New research provides scientific evidence of how policies restricting sugar-laden beverages could be effective in cinching the belt around America’s growing waistline. Sugar sweetened beverages such as soda, sports drinks, and juice have been more firmly tied to obesity, based on the findings of several new studies presented at The Obesity Society’s annual meeting this week.

At the meeting, Jane Wardle, PhD, presented data from the Growing Up Today Study II, which included about 11,000 kids, ages 9 to 15 years old. The study began in 2004, with follow-up surveys conducted about every 2 years, through 2011.  Dr. Wardle found that with each soda consumed per day, the children were 1.8 pounds heavier than their previous surveys predicted they would be. This means that if the child drank 2 sodas per day, they weighed on average 3.6 pounds more than they were predicted. Sports drinks showed a more dramatic difference than soda: the children weighed 3.5 extra pounds per sports drink consumed each day.

Another presentation at the conference showed that replacing sugary drinks with water or other calorie-free beverages reduced the amount of weight gained in children and teens who regularly consumed sugar-sweetened beverages. The presentation covered two studies that were recently published in the New England Journal of Medicine.  The first study was the DRINK trial from Amsterdam, which over an 18 month period either gave children a zero-calorie beverage or a 104-calorie beverage each day.  The study showed that after 18 months, the sugary-drink group weighed 2 pounds more on average than the other group. In the other study, overweight and obese high schoolers in Boston received shipments of either the sugary drinks they usually consumed or sugar-free alternatives. The researchers found that after one year, the sugar-free drink group weighed more than 4 pounds less on average than the students who continued drinking sugar-sweetened beverages.

Lastly, a large study on American adults found that people with a greater genetic predisposition to obesity seem to be more susceptible to the negative effects of sugar-sweetened beverages on Body Mass Index (BMI). Researchers checked participants for 32 gene variants that have been tied to obesity. (Because we inherit one copy from each parent, we have 64 opportunities for these gene risks). The participants had on average 29. They filled out detailed surveys on food and drink consumption and lifestyle factors every four years. The data spanned over several decades. The researchers found that the more sugary drinks someone consumed, the greater the impact of the genes on the person’s weight and risk of becoming obese. This means that people with genes that predispose them to being obese are more susceptible to the harmful effects of sugary drinks on their weight.

Collectively, the studies’ findings strongly suggest that sugar-laden beverages cause people to put on weight, independent of other unhealthy behavior such as overeating and getting too little exercise, scientists say.  On a positive note for soda-lovers, sugar-free drinks did not raise the risk of obesity in these studies, indicating that switching to diet soda may be a way to get the sweet taste of soda without the associated weight gain.

Related Reading:

Soda Industry Pursues Legal Action

Water Vs. Diet Soda Study

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