Diet & fitness

No, seriously: Diet sodas are terrible for you, too

Sep. 19, 2013 at 2:35 PM ET

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nbcnews.com

Want to lose weight, ward off diabetes and still drink something that tastes sweet and fizzy? Grab a diet soda! After all, they're sweetened with zero-calorie sweeteners that give you the sugar fix you need without boosting belly fat.

Except that's all a great myth, as a growing number of studies is finding. Artificial sweeteners, whether sucralose, stevia, aspartame or any of the other increasing number of ingredients being added to this category, are being linked to just as many negative health problems as sugar, in its many forms, according to a new review of five years' worth of research. (Learn the bitter truth about some "natural" sweeteners.)

This new research, published in the journal Trends in Endocrinology and Metabolism, reviewed all the most recent literature on the relationship between artificially sweetened beverages and their effects on weight gain, metabolic syndrome, type 2 diabetes and cardiovascular disease. The authors' conclusion? Artificial sweeteners aren't doing anyone any good. "Data from these recent studies suggest a link between consumption of artificially sweetened beverages and a variety of negative health outcomes...especially in adults," the authors wrote. "In none of these prospective studies was artificially sweetened beverage consumption associated with a significantly decreased risk."

There have been a lot of theories as to why artificial sweeteners don't yield the positive effects they promise. One of the big ones is psychological: People who drink diet sodas perceive them as healthy and then overeat other unhealthy foods. But Susan Swithers, PhD, professor of behavioral neuroscience at Purdue University and lead author of the review, says that that can't explain away everything these studies find. In most of these studies, the authors controlled for total calorie intake and still saw increases in disease risk among people who consume diet drinks. Another theory is that people who drink diet sodas tend to be heavier anyway and therefore already at risk. But again, when weight was taken into account, diet sodas were still linked with increased disease risk. (And that's not all. Check out these other 9 Disturbing Facts about Soda.)

What seems to be the best scientific explanation, Swithers says, is that "artificial sweeteners fail to produce the responses your body expects to produce when you taste sweet things." She writes in her review that sweet tastes send a signal to your gut that something high calorie is on its way. Your gut anticipates this high level of energy, but when it doesn't arrive (artificial sweeteners have no calories), your gut doesn't utilize the food efficiently. And that causes a cascading effect that interferes with your body's hunger signals.

Swithers says that animal studies have also shown that artificial sweeteners interfere with your body's production of a hormone called GLP-1. It's a hormone that regulates your blood sugar levels and your feelings of satiety. It's also been shown to protect your heart, she adds. "We can't say with 100-percent certainty that GLP-1 plays a role," she says, "but when people get artificial sweeteners, they're not releasing things like GLP-1." (Discover how too much diet soda may be bad for your kidneys.)

The conclusions are concerning, considering that, according to data presented in the study, roughly 30 percent of adults and 15 percent of children consume artificial sweeteners. Ironically, increases in consumption of these sweeteners has increased in lock-step with obesity rates over the past 40 years.

The bottom line? The healthiest diet drink for you is water. Or try one of these other healthy "diet" drinks:

Coffee. Coffee is rich in antioxidants and might even protect against diabetes.Green tea. It delivers the caffeine kick you crave, plus a lot more. In addition to fighting cancer and lowering blood pressure, green tea is a natural brain booster: It contains an amino acid called theanine, which enhances mental performance, according Keri Glassman, RD.Super smoothie. Whip one up at night, and save it to enjoy at work tomorrow. Fruits and veggies are natural energy lifters, but so is chocolate -- toss in a dark variety for a healthy helping of caffeine. (Need some suggestions? Check out some of these awesome smoothie recipes.)

More Links:

How to Combat Diet-Soda Belly

8 Healthy Sodas

Diet Water? Artificial Sweeteners May Wind Up In Your H20

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