Are Liquid Diets a Good Idea for Weight Loss?


Losing weight is a very common goal.

Whether for health or appearance, many are searching for the ideal weight loss program.

One category of weight loss diets emphasizes the consumption of liquids, rather than solid foods.

Some programs simply replace certain meals with liquids, while others replace all solid foods with liquids.

This article discusses several types of liquid diets and whether they are recommended for weight loss.

Types of Liquid Diets

Liquid diets are nutrition programs that require you to get either some, most or all of your daily calories from liquids, rather than solid foods.

While there are many liquid diets, most can be grouped into one of the following categories.

Meal Replacements

Some liquid diets involve meal replacement shakes, which are consumed in place of solid foods. Numerous companies sell these shakes for weight loss purposes.

Meal replacement shakes are often lower in calories than typical meals. They can replace one or multiple meals each day (1).

They are designed to contain all the nutrients your body needs to function, including macronutrients (protein, carbs and fat) and micronutrients (vitamins and minerals) (2).

Some weight loss programs use these shakes to account for your entire calorie intake for up to several months (3).

Detox Diets and Cleanses

Other liquid diets include detox diets or cleanses, which require the consumption of certain juices or drinks that supposedly remove toxic substances from your body (4).

Examples of these diets include the Master Cleanse, long-term water fasting and various juicing programs.

Unlike meal replacement shakes, these programs typically rely on a few natural ingredients like juices from certain fruits and vegetables and other botanical ingredients.

Because of this, these diets may not contain all the nutrients your body needs.

Medically Prescribed Liquid Diets

Clear liquid and full liquid diets are examples of diets that are medically prescribed for specific health reasons.

As the name implies, clear liquid diets only allow the consumption of clear liquids, such as water, apple juice, tea, certain sports drinks and broths (5).

These diets may be prescribed before or after certain surgeries or if you have digestive problems.

Full liquid diets are prescribed for similar reasons, but they are less restrictive than clear liquid diets.

They allow most beverages, as well as foods that become liquid at room temperature, such as popsicles, Jell-O, pudding, syrups and some shakes (6).

Liquid Diets Are Often Very Low in Calories

Liquid diets often contain fewer calories than diets consisting of solid foods.

For a liquid meal replacement diet, the total number of daily calories may range from 500–1,500 (78).

However, these diets are often just one phase of an overall weight loss program.

For instance, one weight loss study in 24 obese people involved a 30-day period in which participants consumed 700 calories per day from meal replacements but no solid foods (9).

Over the next 150 days, solid foods were gradually reintroduced. Daily calorie intake increased gradually from 700 to 1,200 calories.

This program was effective for weight loss and reduced body fat from 33% to 26%.

In studies of liquid meal replacement diets, it is common to use this pattern of reintroducing solid foods after a liquid diet has been followed for one to three months (39).

Research has shown that both low-calorie (1,200–1,500 calories per day) and very low-calorie (500 calories per day) diets using liquid meal replacements can be effective for weight loss.

While very low-calorie diets can lead to greater weight loss, they may also lead to greater risks, such as an increased risk of gallstones in some individuals (7).

It is important to note that people participating in studies on low-calorie liquid diets are typically monitored closely by medical personnel.

What’s more, many of these programs are not meant to be followed in the long term.

Certain liquid diets don’t allow any solid foods and thus may not contain all the beneficial nutrients found in whole foods like fruits and vegetables (10).

However, replacing just one or two meals per day with a low-calorie meal replacement shake may be a practical long-term strategy as a complement to eating healthy, solid foods.

They Are Sometimes Prescribed Before or After Certain Surgeries

Although liquid diets are often associated with weight loss programs, there are other reasons why you may follow one.

For example, clear liquids are typically easy to digest and do not leave much undigested material in your intestines (11).

As a result, your physician may prescribe a clear liquid diet before certain surgeries, such as colonoscopies and bariatric surgery.

They may also be prescribed after certain surgeries, such as gallbladder removal and bariatric surgery (12).

Additionally, liquid diets are advised for those who have digestive problems, including diarrhea and vomiting.

However, some evidence suggests that solid food diets that leave minimal undigested materials may be superior to liquid diets (13).



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