What Is a Liquid Diet and Is It Healthy?

Juices, soups, shakes—a liquid diet replaces all your meals with, well, liquids. It's promoted as a fast way to shed pounds, reduce bloating and ease digestive woes. But is it safe?

What Is a Liquid Diet and Is It Healthy?

Liquid diets promise weight loss, detoxing and cleansing. From protein shakes to cold-pressed juices to teas, they claim to have a solution—albeit an expensive one—to your health worries and woes. But are they really the answer?

Should you try a liquid diet? Can they really deliver on their promises? Here we break down what a liquid diet is, including any potential benefits and many of the downsides.

What Is a Liquid Diet?


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A liquid diet consists only of liquids in place of solid food. This includes homemade or store-bought juices and smoothies, homemade protein shakes, premade protein shakes and store-bought liquid meal replacements. You can replace all meals and snacks with liquids or do a partial liquid diet, eating some solid foods as well.

Some companies have specific "juice cleanses" with different phases you can buy. Others offer a variety of liquid meal replacements to choose from based on your goals. These, however, can be expensive and usually must be purchased and mailed to you.

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Reasons for Going on a Liquid Diet

Medical Reasons

Some people go on a short-term liquid diet for medical reasons, such as difficulty swallowing or an intestinal issue.

"It's difficult to make the case for a liquid diet in most cases," says Ayla Barmmer, M.S., RDN, LDN, an integrative and functional dietitian in Boston. "However, the one exception would be when treating small intestinal bacterial overgrowth (SIBO), which is an increasingly common condition given the widespread use of PPIs [proton-pump inhibitor medications for heartburn], chronic stress, antibiotic use and more."

Not everyone with SIBO needs to follow a liquid diet, notes Barmmer, but if it is recommended, it should be done with the supervision of a healthcare professional such as a physician or dietitian.

Keep Reading: Cleanses & Detox Diets—Are They Safe?

Other Reasons for Liquid Diets

Carrot Orange Juice

Featured Image: Carrot-Orange Juice

Some of the more popular reasons for a liquid diet are weight loss and "detoxes." Liquid meal replacements provide a convenience factor—grab your shake and go. Plus, calories and portion sizes are controlled, so it is easier to stay within calorie goals if you're trying to lose weight.

Juice cleanses and detoxes have seen a surge in popularity in recent years but remain controversial in the nutrition world. Juices pressed from fruits and vegetables deliver a healthy dose of vitamins, minerals and antioxidants, but their claims to detox the body are not backed by science.

Liquid diets have pros and cons, regardless of your reason for doing them.

Benefits of a Liquid Diet

three glasses of Green Smoothie on white counter

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Liquid diets can help you lose weight—at least in the short term.

"Sometimes people can lose a few pounds," says Isabel Smith, M.S., RD, CDN, dietitian nutritionist and founder of Isabel Smith Nutrition. "But, they can also gain them back quickly, too."

Liquid meal replacements also provide structure. Following a structured meal plan might lead to greater weight loss than a standard nutrition program.

As far as juice cleanses go, the benefits may be increased vitamin, mineral and antioxidant intake because of the number of fruits and vegetables it takes to extract the juice.

"There are certainly studies that show benefits of juice on antioxidant concentration and anti-inflammatory mechanisms in the human body," says Rachele Pojednic, Ph.D., M.Ed., assistant professor of nutrition at Simmons College, "but it's generally in the presence of a healthy diet or other solid foods. The biggest problem is that people think they are 'detoxing' their organs, which just isn't how your liver, or kidneys, or any other organ works."

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Risks of a Liquid Diet


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Some of the risks and challenges of liquid diets include:

  • Feeling light-headed or dizzy
  • Too few calories
  • Lack of important nutrients
  • Not sustainable long-term
  • Lack of satiety
  • Expensive

"There are very few rewards of going on a liquid diet," says Pojednic. "You may lose a little weight in the short term due to water loss, and perhaps a couple of pounds in the longer term due to a massive calorie deficit. But achieving these results is not typical because the diet is so challenging and makes you feel pretty terrible."

Most people can't last more than a few days before giving in to everything they were restricting, which just leads to overeating, guilt and gaining back the weight you lost.

In addition to feeling hangry, you might be missing important nutrients, too. Juices have vitamins and minerals, but they don't have fiber, fat or protein—all necessary for a healthy body. Drinking juice alone can lead to "debilitating headaches, overwhelming hunger and diarrhea," says Pojednic. "Despite the hype that you feel this way because your body is 'detoxing,' these symptoms are actually because your calorie intake is so low, your blood sugar in between 'meals' is tanking, your body is responding to never feeling satiated and there's nothing in your gut to bulk up your stool."

The amazing thing about our bodies is that they take care of the cleansing for us and are designed to detox regularly all on their own.

"Your body operates on very tightly regulated signaling mechanisms to keep you upright, functioning and clearing out molecules that it doesn't need," explains Pojednic. "Your liver has very specific enzymes to 'detoxify' your body. Some foods can influence these enzymes, but flooding your body with liquid isn't going to dramatically change those mechanisms or 'flush out your system,'" says Pojednic.

One final downside to liquid diets? Cost. Subsisting on liquids alone gets expensive.

Nutrient Absorption

There is a difference in how your body absorbs liquids and solids. Solids come with an extra step in the digestion process: chewing. Chewing your food increases your fullness factor. Fiber also slows down digestion, helping you stay full longer, but juices lack this key ingredient.

"The sugars—glucose and fructose—in the juice will cross the intestinal wall much more quickly without the soluble fiber present in whole fruit because that fiber barrier will be missing," says Pojednic.

And while you are getting a concentrated dose of vitamins and minerals from juice, you might not absorb them all. Vitamins A, D, E and K require fat in the food you're eating so that they can be absorbed into your body.

Who Should Never Do a Liquid Diet?

Liquid diets can be difficult enough, but there are certain people who should never consider a liquid diet. In fact, liquid diets could be dangerous if you are pregnant, breastfeeding, on certain medications, have had a recent procedure, or have intestinal or digestive issues.

Bottom Line

Not sure if a liquid diet is right for you? Talk to a dietitian, who can guide you through the pros and cons based on your goals. If you choose to go for it, choose beverages that have protein, carbohydrates and fat to help you stay full and allow vital nutrients to be absorbed. Swapping juices for smoothies can help. Consider having one liquid meal per day instead of all three. And don't stay on the liquid diet for long.

"You probably won't do much damage if you keep it to less than three to seven days," says Pojednic. "In the meantime, though, prepare to feel like crap."

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