Every January, the internet becomes saturated with weight loss content and toxic diet culture rears its ugly head. Though the “it fad” tends to change from year to year (keto in, paleo out) there’s one fad that won’t seem to die: liquid diets. They come in different forms — juices, smoothies, meal replacement shakes, broths — but the idea is the same: Drink all your meals (or most of them) and lose weight, fast. The promise is that it will also magically cleanse your insides and rid your body of toxins. (Hint: Your liver already does that for you.)
Liquid diets are often depicted as a quick fix, a shortcut that gives you dramatic results with little effort. Why put in work when you can drink your food and call it a day? Thanks to social media and celebrity endorsements, cleansing and detoxing has become more popular than ever. And more recently, a liquid diet was a major part of the plot in a popular television show.
In Netflix’s Insatiable, teenage protagonist Patty drops a significant amount of weight thanks to a liquid diet she goes on after her jaw is broken and wired shut. When the wires come off and Patty can eat solid food again, the weight stays off too (a major plot hole) and she finally gets revenge on her bullies. Besides being problematic and offensive, Insatiable glamorizes a draconian, medically necessary liquid-only diet as a viable weight loss method. The reality of the liquid diet isn’t depicted, only the results. As a teenager, I also had my jaw broken and wired shut, and I can tell you this is not what happens when you drink your food through a straw for four to six weeks.
Sure, people may not be rushing to get their jaw wired shut to lose weight. But they arevoluntarily consuming liquefied food, and very few calories of it, for extended periods of time. Liquid diets are an extreme form of restriction, but they are seldom portrayed this way. They have become normalized and rebranded as a “five-day juice cleanse” or the “bone broth diet.”
So what do liquid diets actually do to your body and brain, and is there ever a healthy way to do them for weight loss? We spoke to two experts to find out: Dr. Michael Crupain, a board-certified preventive medicine physician and coauthor of What to Eat When, and Abby Langer, a registered dietitian and owner of Abby Langer Nutrition.
Note: For the purposes of this article, a liquid diet is defined as replacing all or most meals with liquids for several days or longer. We aren’t talking about the occasional juice or shake for breakfast. This also excludes medically necessary liquid diets, which may be prescribed before or after certain procedures, or for medical conditions.
You tend to lose “water weight.”
Obviously, what’s in the liquid matters. A juice cleanse, for example, is typically very low in calories and higher in sugar, whereas meal replacement shakes may provide more protein and other nutrients. But for the most part, liquid diets tend to be lower in calories than your regular solid-food diet.
“One common thread among all the liquid diets I’ve seen in the last 20 years is that none have adequate calories or nutrients to sustain a person over the course of weeks or even days,” Langer told BuzzFeed News. Most liquid diets are meant to take weight off very quickly, she pointed out. They may provide anywhere between 1,000 and 1,500 calories a day, depending on what and how much you’re drinking.
When you go on a low-calorie liquid diet, you are essentially starving your body and forcing it to use up your stored energy. First, it starts burning through your glycogen, a form of glucose that the body stores in the liver and muscles. Glycogen also binds to several times its weight in water, the experts explained. “As you burn through glycogen you lose the water attached … and you store somewhere between five to ten pounds of water weight,” Crupain told BuzzFeed News.
So yes, you can lose weight on a liquid diet in the beginning, but it’ll probably come back pretty fast. “As soon as you start eating food again, your body starts building up your glycogen again and with that comes the water, back,” said Crupain.
You may start losing fat, and then muscle.
What if you’re on the liquid diet for longer? Once your body burns through the glycogen it will go to its longer-term energy stores: fat cells and muscle. So you can eventually lose some fat, but also muscle mass, which is hard to gain back.
After you end the diet and return to solid food, you may also end up gaining more weight than you lost in the first place, Langer explained. Naturally, most people will have a tendency to overeat after ending a very restrictive diet. “Your body craves food and you overeat to compensate for the calories and nutrition you didn’t get while on the liquid diet,” Langer said. Depending on your body composition goals, this may not be ideal.
So according to the experts, liquid diets are not an effective or sustainable weight loss method. “You may lose some weight but it’s very hard and you’re not getting all the fiberand vitamins and nutrients your body needs to work. … You’re starving yourself in an unhelpful way,” Crupain said. There are more sustainable, healthier ways to lose weight.