What You Need to Know About That New Study That Says Diet Soda Helps You Slim Down

A new head-scratching study is challenging just about everything we think we know about diet soda—namely, that it makes you gain weight. According to the new research, published in the journal Obesity, the reverse is true: Drinking diet soda can speed your weight-loss efforts.

But before you revert back to your former diet soda habit, you need to consider the whole picture.

First, here's how the study—which was funded by the American Beverage Association (members include Coca-Cola and Pepsi)—went down: Researchers divided about 300 diet soda-drinking adults who each weighed approximately 200 pounds into two groups: one that was instructed to continue drinking diet soda, and one that was told to cut out the drink altogether. While the average person banned from drinking diet lost nine pounds over 12 weeks, those who kept drinking the stuff lost 14 pounds on average in the same amount of time. Hm.

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But that doesn't mean diet soda is some weight-loss miracle drink. First off, both groups were regular diet soda drinkers to begin with. As the researchers note, going cold turkey (especially on addictive substances such as artificial sweeteners) is extremely difficult and can sap motivation for other weight-loss efforts. Therefore, the participants who were allowed to drink diet soda may have been better able to curb other unhealthy cravings. In fact, science suggests that willpower is a limited resource, says nutritionist Jaime Mass, R.D.N., L.D.N. Use it up on one thing (like forgoing diet soda), and you have less left over for saying no to trans fat-laden cookies or pushing yourself just a bit harder at the gym.

MORE: Drinking Soda is Even Worse For You Than We Thought

However, sticking with diet soda when you're trying to rehab your other eating habits does pose some risk. Artificial sweeteners can throw off your body's hormone levels, contributing to poor blood sugar control and mounting cravings, says Mass. Artificial sweeteners are between 180 and 13,000 times sweeter than sugar, and your body reacts to sweetness with signals to eat more sweet stuff, according to the Harvard School of Public Health. Plus, by providing so much lip-smacking sweetness without any calories, artificial sweeteners thwart your body's natural ability to gauge your calorie consumption. That's likely part of the reason the average two-a-day diet soda drinker has a waist circumference that's five times larger than someone who shuns the stuff, according to 2011 research from the University of Texas.

Basically, there are still gaps in the research on diet soda's effects on weight, and no one really knows what the long-term health impacts of diet soda are, says Mass. But one thing's for certain: Diet soda is no weight-loss superdrink.

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