For lots of healthy types, the frequently stated fact that Diet Coke might be “empty calories” actually goes down just fine compared to office cupcakes, which they’re not regularly scarfing.

And reaching for a diet soda fits nicely into the “allowable-exceptions” category of a healthy lifestyle. You know, along with a glass of Sancerre, the occasional dinner at Eataly, and watching the Real Housewives.

But should you allow Diet Coke a free pass? (Ditto: Housewives.)

While sipping diet soda seems harmless, especially in the context of a generally healthy life, a surprising number of substantial studies show the opposite, that drinking Diet Coke and Aspartame can greatly interfere with your health.(Another seemingly harmless version? Diet Pepsi with Splenda—not as good for you as once thought.)

As Dr. Helen Hazuda, professor of medicine at University of Texas Health Science Center at San Antonio, recently found, “[Diet soda] may be free of calories, but not of consequences.” And she wasn’t talking about the caffeine.

Interpreting the data of two studies, Dr. Hazuda pointed out that it caused a blood sugar spike in mice, and suggested that diet sodas may inhibit the signal that tells you when you’re full.

Here are 6 more reasons to give up diet soda:

Originally posted July 31, 2012; updated March 12, 2016.

1. It messes with your skin.

Diet Coke lowers your pH levels, which can cause acne, and zap you of radiance. We need a high level of alkalinity for our bodies to be healthy and expressed in our glowing complexion, explains Dr. Jeanette Graf, author of Stop Aging, Start Living: The Revolutionary 2-Week pH Diet. As Dr. Graf told us, “If there’s one thing you should never consume, it’s soda. Soda is an extreme acid-forming substance which will lower your pH level dramatically.”

2. It alters your mood.

The mood-food connection is ever-rising, and Aspartame in Diet Coke can really do a doozey on those with anxiety, depression, and bipolar disorder. Aspartame is also on an EPA list of potentially dangerous chemicals contributing to neurotoxicity, right under arsenic. So that’s kind of saying it could alter your brain, too.

3. Weight gain and belly fat.

Ironically, we actually gain weight from Diet Coke. In two studies conducted by the School of Medicine at The University of Texas Health Science Center San Antonio, those “who said they consumed two or more diet sodas a day, experienced waist circumference increases that were 500 percent greater than those of non-users.”

4. It is linked to diabetes and heart disease.

When waist circumference (belly fat) increases, this contributes to diabetes and heart disease, which a 2010 study in the Journal of General Internal Medicine confirmed.

5. It makes your kidneys sluggish.

Diet soda may interfere with the kidneys, found the Harvard Nurse’s Health Study, which reported a 30 percent drop in kidney function with just two servings of diet soda each day.

6. Aspartame’s been linked to cancer. A lot.

Aspartame is “generally recognized as safe” by the FDA while substantial data has shown its link to cancer. The Center for Science in the Public Interest (CSPI) cautions against Aspartame because it’s poorly tested, and contains three well-recognized neurotoxins. Aspartame was found to increase cancer risk if exposure begins in the womb, reported a study at the Cesare Maltoni Cancer Research Center. And various studies have linked lymphoma and tumors in rats. And beware the BPA of cans and caramel coloring, reports Grist.

Kind of takes the fizz out of it, right?

Do the best experiment out there—the one on your own body. We dare you to lower your soda intake for a week and see if you notice any changes in skin, weight, or mood. Report back in the Comments! —Jennifer Kass and Melisse Gelula

Need something else to sip on? One family nixed their diet soda habits by drinking juice, which is an equally friendly on-the-go option.