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The Nuance

Can Drinking Seltzer Lead to Weight Gain?

Turns out those bubbles may be trouble

Photo by Brittany Greeson/The Washington Post via Getty

Every week, the Nuance will go beyond the basics, offering a deep and researched look at the latest science and expert insights on a buzzed-about health topic.

TThe beverage that was once relegated to Perrier-sipping sophisticates is now among the most popular in America, and for obvious reasons: Who wants to drink boring still water when you can titillate your taste buds with a snappier alternative like LaCroix Pamplemousse? Especially for erstwhile (or still-hooked) soda addicts, sparkling water is a helpful aid — a drink with all the effervescence and none of the sweetener-induced guilt.

But every now and then, sparkling water devotees may have heard whispers that the bubbles in their favorite beverage may not be harmless.

Historically, much of that whispering has to do with the studied links between certain carbonated beverages and bone health. While results have been mixed, some research has linked carbonated drinks with an increased risk for bone fractures. But sparkling-water lovers can breathe easy on the bone-health front; while some of the study headlines seem scary, the concerns surrounding carbonated drinks and bone health seem relegated to soft drinks — colas in particular.

Unlike sparkling water, soft drinks often contain phosphorous, which may impede bone health by disrupting the body’s calcium-to-phosphorus ratios. “My work showed a negative effect on bone from cola, due to its phosphoric acid content,” says Katherine Tucker, PhD, a professor of nutritional epidemiology at the University of Massachusetts, Lowell, and author of a 2006 study linking colas — but not other carbonated beverages — to low bone-mineral density. “We did not find any negative effect of carbonated water,” Tucker adds.

Some research does link flavored sparkling water to tooth enamel erosion — a finding the authors of a 2007 study attributed to the acidic profile of these drinks. But when it comes to plain sparkling water, there seem to be no concerns regarding dental health.

“We saw no difference between sparkling and still water.”

The same is true of sparkling water’s thirst-quenching abilities. A 2015 study in the American Journal of Clinical Nutrition found that sparkling and still water scored about the same on a “beverage hydration index.” In fact, the study found that sparkling water disturbed the body’s electrolyte balances a little less than still water, which in some cases could be viewed as a mild hydration benefit.

But really, the two were neck-and-neck. “We saw no difference between sparkling and still water,” says Ronald Maughan, PhD, first author of the hydration study and emeritus professor of sport and exercise nutrition at Loughborough University in the UK.

Maughan points out that there could be some individual variation when it comes sparkling or still water’s effects on hydration, but that variation is attributable to personal preference. “Some people may choose to drink more of a sparkling water than of a still water, either for the novelty value or because they prefer the taste,” he says. “Others, though, may dislike sparkling water and would therefore not drink as much as if still water was available.”

The only major question mark associated with sparkling water has to do with its potential impacts on appetite and the stomach’s hunger hormones.

A 2017 study from researchers in the West Bank set out to determine whether the carbon dioxide gas in carbonated drinks — basically, the stuff that gives sparkling water its sparkle — could explain some of the links between soft drinks and obesity. While most soda studies have focused on soda’s sugar or artificial sweeteners, “the effects of one main component in soft drinks” — namely, the carbon dioxide gas — “has not been studied thoroughly in any previous research,” the study’s authors wrote.

Their research found that people who drank carbonated beverages — including those who drank carbonated water — had higher circulating levels of the hunger hormone ghrelin than those who drank still water. In fact, those who drank carbonated water had a threefold spike in ghrelin levels compared to those who drank plain H20. The authors speculate that the gas in carbonated water could push on the walls of the stomach in ways that trigger the release of ghrelin and stimulate appetite.

The West Bank study team also examined the effect of carbonated beverages on rats and found that a sparkling beverage significantly upped the rodents’ ghrelin levels, food intakes, and weight gain compared to drinking similar amounts of the exact same beverage, albeit one that had been stirred for two hours to remove its carbon dioxide bubbles.

Those who drank carbonated water had a threefold spike in [hunger hormone] levels.

It’s important to note that the research on ghrelin is controversial. While some studies have linked elevated ghrelin levels to increased food consumption and a heightened risk for obesity, others have argued that the relationship between ghrelin and food intake is complex and not as simple as saying higher ghrelin equals greater appetite and food intake.

Still, the finding that carbonated water could alter ghrelin levels compared to plain water is evidence — albeit preliminary and in need of follow-up — that sparkling water may not be as anodyne as plain.

I write about health and science. I live in Detroit with my wife and kids. I’m trying to learn German, but my progress so far is nicht gut.

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