What is a liquid diet and is it healthy?

Should you make room for more liquid meals? Photo from Tribune News Service

By Matthew Kadey
Posted on September 22, 2023

In America, there is no shortage of diets to cling to: Paleo, plant-based, keto, DASH — all with their merits and pitfalls.

Another popular choice is the liquid diet, or the so-called “juice cleanse.” Whether you drink juices, blender shakes, tea, broths or soups, liquid diets are nutrition programs that direct you to get either some, most or all of your daily calories from liquids rather than solid foods.

Some emphasize meal-replacement drinks, while others focus on juices and clearer liquids. In some cases, people will do a partial liquid diet, eating some solid foods as well.

People are prescribed a short-term liquid diet for medical reasons, such as difficulty swallowing, an intestinal issue or recovering from surgery, but it’s also sold to the general public as a quick way to drop pounds, ease bloating and reduce digestive woes.

Detoxing and cleansing are other words tossed around to promote the merits of a liquid diet.

In any form, this eating, or shall we say not eating, pattern is controversial in the nutrition world. Many think it will be an easy way to lose weight, but the truth is much more complicated.

Should you try a liquid diet, or are you better off sticking with solid food? Here we break down any potential benefits and many of the downsides.

Reasons to try a liquid diet

Certainly, liquid diets can help you shed a few pounds quickly. And you may have a sense of feeling “cleaner” once on the diet, which for some people can be the catalyst to making more sustainable long-term improvements in how they eat.

Sometimes we need a nudge, and sometimes that nudge needs to be a bit drastic. It’s also a diet that can provide people with some structure and calorie control.

“Often it can be simpler to use liquid meal replacements (calorie-controlled shakes) instead of meals as a way to sustainably reduce calories,” said Colleen Tewksbury, Ph.D., RD, assistant professor at Penn Nursing and spokesperson of the Academy of Nutrition and Dietetics.

Since portion sizes and calories are typically more easily controlled on this diet, it can be easier for people to stay within weight loss calorie goals. After all, you probably aren’t going to wander into the kitchen at 10 p.m. to whip up a smoothie, whereas it’s much easier to nibble on cookies.

If a variety of liquids are consumed with different nutritional profiles, such as yogurt drinks or smoothies, for a reasonably short amount of time, there should not be any serious health issues.

It’s also hard to deny that liquids like green juices provide a convenience factor — grab your drink and go. And if someone is just replacing a single meal with a meal replacement drink, then Tewksbury said it could make the diet more sustainable to follow long-term.

Reasons to avoid a liquid diet

Tewksbury stresses that many people find an all-liquid approach challenging, to say the least. It can be disheartening to lose weight only to gain it all back and then some, which is a real risk factor when going on a crash diet like this.

You should know that there is a dearth of studies showing any lasting weight loss or health improvements on this diet beyond what can be achieved by a calorie-controlled diet that includes solid food.

One reason why is that a drastic diet like this typically has a low adherence rate. The diet is so challenging to stick to for a variety of physical, mental and social reasons that few people will last very long on it.

In addition, diets like these don’t often lead to lasting weight loss because they don’t do anything to change your permanent eating habits.

And the hunger and cravings it can generate may leave people giving in to everything they were aiming to restrict, which Tewksbury cautions can lead to overeating and a collapse of eating behaviors, not to mention generating feelings of guilt and shame.

Research shows that, calorie-for-calorie, liquids are less satiating than solid food. Chewing food before digesting it contributes to feelings of fullness, which doesn’t happen in the case of liquid diets.

As for the detox side of things, “there is no evidence to support the claims that liquid diets or juice cleanses ‘detox’ the body,” Tewksbury said. “That is a job for your kidneys and liver.”

Juices pressed from fruits and vegetables deliver a healthy dose of vitamins, minerals and antioxidants, while meal replacement drinks can supply high amounts of protein.

But Tewksbury cautions that a liquid-only diet opens the door for a handful of nutrient shortcomings. “Any diet that eliminates entire food groups is increasing the risk of nutritional deficiencies.”

And with so little fat in your diet, you may have trouble absorbing sufficient amounts of fat-soluble nutrients like vitamins E and K. And all that liquid paired with a lower intake of fiber can result in some unpleasant changes in your bowel movements.

Furthermore, if you are using store-bought cold-pressed juices, meal replacement drinks and bone broth, the diet can get expensive fast.

Ultimately, there is no “one size fits all” diet. If you want a safe, effective weight loss plan, it’s best to gravitate toward a whole-food, calorie-conscious diet that you can sustain over the long haul. And, yes, there is room for smoothies and green juices in that.

Reprinted with permission from Environmental Nutrition, a monthly publication of Belvoir Media Group, LLC, 1-800-829-5384, EnvironmentalNutrition.com.