Soda, Cola, Cold Drink.

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TORONTO, Ontario — We often hear that soda is unhealthy, and scientists are now getting a clearer picture of the damage it causes. A review of recent nutrition studies adds more proof that drinking sugary beverages directly leads to higher body mass index and weight of both children and adults. The average 12-ounce serving of sugary beverages like soda has over 140 calories and over eight teaspoons of sugar, the recommended limit for added sugar for an entire day!

The current findings could influence changes to the USDA Dietary Guidelines for Americans, researchers say.

Being overweight or obese increases a person’s risk for several health problems, including diabetes, heart disease, and certain cancers. One of the reasons for these negative health outcomes is the makeup of added sugar. In these drinks, sugar is typically made from different types of liquid sugars like high-fructose corn syrup. This glob of sugar increases blood glucose levels, which triggers a glycemic response that, over time, could cause insulin resistance and diabetes.

The fructose in added sugar impacts the liver and ups a person’s risk of fatty liver and metabolic disease. Fructose also elevates uric acid levels, which is another driver towards insulin resistance and other diseases. Spikes in insulin can, in turn, affect your appetite and encourage overeating that leads to excess insulin in the blood.

Every can of soda influences weight gain

Vasanti Malik, an assistant professor of nutritional sciences at the University of Toronto, worked with colleagues to review 85 studies from the past decade that looked at sugary beverages and weight gain among adults and children. Cohort studies, which track people’s health outcomes for long periods of time, show that each serving-per-day increase in sugary drinks had an association with an almost one-pound increase in body weight among adults.

Children had a 0.07-unit higher body mass index. As both children and adults drank more sugary beverages, weight gain increased, further showing strong evidence of a cause-and-effect relationship.

Child drinking a can of Sprite soda
(Photo by Phinehas Adams on Unsplash)

While the review did not explicitly say you need to completely cut out sugary beverages, there are benefits to limiting intake even if it’s just one drink a day. Adults who drank one 12-ounce serving a day were more likely to be half-a-pound heavier after one year. After a decade, that could be about five pounds. Children showed a 0.03-unit higher BMI for each additional sugar-sweetened beverage per day in one year.

“Although these results may seem modest, weight gain is a gradual process, with adults averaging about one pound of weight gain per year,” says Malik in a media release. “So, limiting SSB consumption could be an effective way to prevent age-related weight gain.”

Sugary drinks can be addictive

While more research is necessary, some studies suggest limiting sugary beverages is hard to do because they activate the dopaminergic reward system in the brain. This encourages addictive behavior to continue the unhealthy habit.

Consuming high amounts of soda, fruit juices, and sports drinks contributes to obesity’s continued status as an ongoing epidemic, the researchers say. In 2016, almost two billion adults were overweight and 650 million met the criteria for obesity. One concern among public health officials is the growing rate of obesity among young children and adolescents — a condition which is also more prevalent among young adults now as well. Childhood obesity rates have increased more than four-fold globally since the 1970s.

Malik remains optimistic the world can scale down on how many sugary beverages they drink through sugar taxes. There are currently 85 countries with a tax on sugar-sweetened drinks.

“All these efforts will push intake down, but it’s important to remember that as that happens, people need access to clean, safe drinking water as an alternative,” advises Malik.

The review is published in the American Journal of Clinical Nutrition.

About Jocelyn Solis-Moreira

Jocelyn is a New York-based science journalist whose work has appeared in Discover Magazine, Health, and Live Science, among other publications. She holds a Master's of Science in Psychology with a concentration in behavioral neuroscience and a Bachelor's of Science in integrative neuroscience from Binghamton University. Jocelyn has reported on several medical and science topics ranging from coronavirus news to the latest findings in women's health.

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