Does Sparkling Water Make You Hungry?

Wendy writes: “I read that drinking sparkling water increases hunger hormones, making you eat more. Is this true?”

First, they took away our soda. Too much sugar!

Then, it turned out that diet soda might be just as bad. Despite being sugar- and calorie-free, the artificial sweeteners may affect our intestinal bacteria in ways that promote weight gain.

And now they’re coming for our plain sparkling water, too? Will they stop at nothing?

Does Carbonation Stimulate Your Appetite?

In fact, last year, researchers did find that drinking plain carbonated water can increase ghrelin, a hormone that’s associated with hunger.

The first phase of the research was carried out in lab rats. The rats were given their regular rat chow to eat. To drink, they got either plain water, diet soda, regular soda, or regular soda that had been stirred until it was completely flat or non-carbonated.

Shockingly, the rats that drank the carbonated beverages ate more food and gained more weight than the rats that drank plain water or flat soda. In other words, the fizzy drinks led to weight gain even when the fizzy drinks contained no calories. And the rats that drank sugary soda without carbonation fared about the same as those that drank plain water.

Lab tests confirmed that the rats who drank carbonated beverages had higher levels of ghrelin, a hormone that makes you feel hungry. But rats aren’t people. Maybe this doesn’t apply to humans. Then again, maybe it does.

The next phase of the study involved 20 healthy men between the ages of 18 and 23． (Aside: why do so many studies like this involve college-aged men? Because researchers tend to work in University settings and when they are looking for subjects, there is always an ample supply of students to experiment on. Using only males saves them the trouble of controlling for things like monthly hormonal fluctuations. But I digress…)

When they tested the effects of various beverages in these young men, the results mirrored what they saw in the mice. Ghrelin levels were about twice as high after drinking flat sugar-sweetened soda than they were after drinking plain water. But they were six times higher after drinking fizzy soda. What’s worse, diet soda and plain sparkling water had the same effect on ghrelin as sugar-sweetened soda.

Next they’ll be telling us that kale is actually bad for us. Oh, wait, they already tried to tell us that. Well, you know what I mean.

I dutifully refrain from drinking soda and diet soda but I drink plenty of carbonated water. Like many of you, I like the bubbles and there didn’t seem to be any downside. (In fact, depending on what brand you choose, sparkling water can be a significant source of minerals!)

See also: Is Carbonated Water Bad for You?

Surely we can find some problems with this study! Twenty subjects is a very small sample size—and it’s not at all clear that the results would be the same in people who are not healthy 20-year-olds. In fact, a similar study done in obese subjects ranging from 20 to 50 found almost the opposite. Ghrelin levels were significantly lower after drinking regular soda than after drinking water or diet soda. As you might expect, the calorie content of the beverage had a bigger impact on hunger hormone release than whether or not the beverage was fizzy.  

Hunger Hormones Are Not the Whole Story

But here’s the bigger point that I want to make. Ghrelin is only one of several hormones linked to hunger and appetite. For example, in the rat study I mentioned earlier, the type of beverage had no impact on the release of cholecystokinin (CCK), another hormone linked to satiety.  

Moreover, these hormones are only one of many factors that contribute to our subjective experience of being hungry. (See: How to tell if you’re really hungry). The differences in ghrelin levels after various fizzy and nonfizzy beverages did not predict how hungry people actually felt or how much they ate at subsequent meals. Another study in young women didn’t measure hunger hormones but simply asked the women to describe their level of hunger. They reported feeling less hungry after drinking a carbonated beverage than a non-carbonated one.

We can engineer our environment and cultivate awareness so that our appetite doesn’t get hijacked by things that have nothing to do with hunger cues.

And, finally, how hungry we feel is only one of many factors that determine how many calories we take in. 

Will Drinking Sparkling Water Lead to Weight Gain?

Even if drinking sparkling water does temporarily increase your ghrelin levels, that doesn’t necessarily mean you will feel hungrier, eat more, or gain weight as a result. In fact, I would argue that factors such as the time of day, location, activity, your emotional state, and availability (and even just the visibility) of food often have a lot more influence over what you eat than your ghrelin levels.

Fortunately, unlike lab rats, we are not at the mercy of our hormones. We can decide what and how much to eat, based not just on how we feel at the moment but how we want to feel (and look) in the future.

Even better, we can engineer our environment and cultivate awareness so that our appetite doesn’t get hijacked by things that have nothing to do with hunger cues.

We can also pay attention to how different foods and drinks affect our appetite—and this can help us choose better. If you drink fizzy water as an alternative to caloric beverages—such as soda, alcohol, or fruit juice—this can lead to taking in fewer calories, not more. On the other hand, if you drink lots of sparkling water and you feel ravenous all the time, you could do a little experiment to see whether switching to an uncarbonated drink helps ratchet down your appetite.

I’m eager to hear the results of your experiments. Post your thoughts here or on the Nutrition Diva Facebook page.

Image of sparkling water © Shutterstock