Celebrities like Oprah, Gwyneth Paltrow and Queen Bey herself have been praising the liquid-diet gods for years. So when we learned that Lily James, Miss Goody Glass-Shoes herself in the new live-action movie adaptation of Cinderella, went on a liquid diet to squeeze into her corset, we weren’t shocked—a pretty starlet on a juice-y, soup-y, cayenne-pepper-and-weirdness fast isn’t exactly breaking news.
And we’ve definitely seen enough fad diets roll through to know that detoxes aren’t always nice to your bod. But how bad is an all-liquid diet, really? Pretty awful, it turns out. We’ve got the skinny on why they’re so bad for you.
They Deprive You of Nutrients (Which Generally Makes Life Awful)
An all-juice detox might knock out your daily helping of produce, but they’re typically missing the fibers and nutrients you could only get from real food—leading to pretty terrifying consequences.
“Liquid diets are usually not going to provide you everything your body requires,” says Jaime Mass, R.D., president of Jaime Mass Nutritionals. This could lead to a whole menu of awful: vitamin deficiencies, muscle breakdowns, low energy, thinning hair, lack of focus, dizziness, nausea, headaches and—surprise—a sucky mood.
And if that doesn’t terrify you into a Hard No, know that not all juices—not even the seemingly healthy ones—are your BFF: some juices have the carbs of a 20 oz soda, and some smoothies equate to eating two candy bars.
“Now imagine drinking that four to six times a day,” says Mass. “When you consume sugar in large quantities, the body will bring fluid into the gut to balance it out, which can lead to stomach upset, bloating, pain, and diarrhea.”
They Mess with Your Natural Body Systems
Liquid diets often tout their “cleansing” properties, but the truth is that your body already has systems in place to do all the cleansing it needs.
“Your liver and other organs naturally remove so-called waste from your body,” says David Grotto, R.D, David Grotto, R.D., founder of a nutrition consulting company in Illinois. “Eating whole grains, produce, healthy fats, low fat dairy, and lean protein keeps these organs and your body’s elimination process in top condition.”
But liquid diets—and almost all other detox plans—put your body into starvation mode, forcing your body to feed off of itself, hanging onto calories and burning into lean muscle for energy, says Mass. The loss of lean muscle can mess with your ability to burn calories, and interfere with your heart and muscle performance. Translation: if you’re a gym-goer or an athlete, you could end up seriously injured.