In the pursuit of fitness and weight loss, liquid diets have become a popular choice. These diets involve consuming all or most of your daily calories from liquids, rather than solid foods. Liquid diets come in various forms, including medically prescribed diets, detox cleanses, and meal replacement programs designed for weight loss. While liquid diets may offer some benefits, it's crucial to understand their potential risks and whether they are a sustainable long-term solution.
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 Replacement Shakes
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 . They are designed to contain all the nutrients your body needs to function, including macronutrients (protein, carbs and fat) and micronutrients (vitamins and minerals) . Some weight loss programs use these shakes to account for your entire calorie intake for up to several months .
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 . 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. For example, the Master Cleanse consists of 3-10 days of only consuming a special beverage made of lemon juice, maple syrup, cayenne pepper and water .
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 . 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 .
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Benefits of Liquid Diet Shakes
Decreased Caloric Intake and Weight Loss
The main benefit of a juice cleanse, a type of liquid diet, is decreasing your caloric intake, which will then help you to lose weight. 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 . 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. However, this was likely because they ate fewer calories than the solid-food group. Replacing some or all meals with liquid meal replacements can promote weight loss. However, this is due to a reduced calorie intake.
Convenience and Nutrient Density
A meal replacement shake is one way to make sure you have a healthy option if you know you won’t have time to stop and eat. It might be easy to stop by a fast-food restaurant, where many options aren’t healthy. Plus, you’ll probably spend more on a burger than you would on a meal replacement shake. Meal replacement shakes are high in protein, so they fill you up but may not load you with extra calories. This aids in weight loss without giving up muscle mass. Research has found that meal replacement shakes can help with weight loss. One study tracked two groups of people as they tried to lose weight over the course of 3 months. At the end of the study, the group that did not use meal replacement shakes lost only 1.5% of their initial body weight. The group that used replacement shakes lost 7.8%. A meal replacement shake is a good addition to your diet if you’re watching your weight or trying to lose weight. One downfall when losing weight is feeling hungry, and meal replacement shakes can help you overcome that obstacle. In addition to protein that helps you feel full, meal replacement shakes are often high in fiber. This helps healthy digestion, so you don’t get bloated or have constipation.
Medically Prescribed Uses
Liquid diets are used for more than just weight loss. Your physician may prescribe a liquid diet before or after certain surgical procedures or if you have particular digestive problems. Clear liquids are typically easy to digest and do not leave much undigested material in your intestines . 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 . Additionally, liquid diets are advised for those who have digestive problems, including diarrhea and vomiting.
Risks and Disadvantages of Liquid Diet Shakes
Not a Good Long-Term Weight Loss Strategy
Liquid diets are not beneficial for weight loss in the long run. While they aid quicker loss of weight, the weight gain after switching to solid food diet is equally quicker. Moreover, solid foods contain some essential nutrients which are important for the healthy functioning of the body. Hence having a diet in moderation, which is simpler to follow, is helpful for sustaining your weight reduction for a long period of time. Solid foods contain many necessary nutrients. Therefore, it is not recommended to stay on a diet consisting of liquids alone in the long term. Even in studies showing impressive results from liquid meal replacements, solid foods were reintroduced after several weeks or months . Short-term, low-calorie diets can cause you to lose body weight quickly due to the loss of carbs and water, both of which are normally stored in your liver and muscles . Much of the weight you lose during these short-term liquid diets may not be due to fat loss . Once you resume a normal diet, you will likely regain much or all of the weight that you lost as your carbohydrate and water stores are replenished . Short-term crash diets don’t typically lead to lasting weight loss because they don’t do anything to change your permanent eating habits .
Diets that contain solely juices or special beverages are not good long-term strategies. These programs may lead to some rapid weight loss but will probably not lead to lasting fat loss. Focusing on sustainable, long-term dietary changes is a better strategy.
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Potential Side Effects
Since most liquids are low in fiber, it is quite likely that one might get constipated when on a liquid diet. Also, liquid diets increase chances of gallstones. Increased risk of nutrient deficiencies is another possible side effect of following a liquid diet. One side effect of a liquid diet is constipation, which may be due to the low fiber content of most liquids . Additionally, very low-calorie diets (500 calories per day) may lead to a higher risk of gallstones than low-calorie diets (1,200-1,500 calories per day) . Following a liquid diet over the long term could increase your risk of nutrient deficiencies, particularly if you are only consuming juices or other beverages that do not contain all essential nutrients .
Not Suitable for Everyone
Meal replacement liquid diets or even the detox liquid diets might not be helpful for people who feel more hungry when the consume liquids instead of a small healthy meal or a snack. What’s more is that meal replacement shakes are more expensive than your healthy solid foods. Several groups of people should not consider a liquid diet, such as pregnant or nursing women, children and adolescents and those who are underweight .
Some people find emphasizing liquids to be an easy way to reduce calorie intake, while others find it difficult. First, consider whether replacing foods with liquids will help you reduce your calories and if it’s a sustainable diet strategy for you.
Artificial Ingredients and Low Calorie Concerns
Often, meal replacement shakes have a lot of artificial ingredients because the powder mixes are processed. The artificial ingredients help preserve the product and boost nutrients. Many shakes also include added sugars so they taste better. Be sure to read labels carefully. Meal replacement shakes are typically between 150 and 200 calories, which is probably nowhere near what you would eat during a meal. Be sure to make up calories with other meals and snacks.
Appetite and Hormonal Responses
There is strong evidence that liquid foods elicit weaker appetitive and dietary responses than solid foods . Furthermore, the sensation of satiety occurs more rapidly following solid food consumption compared to liquid consumption and exists for a longer time period, delaying the return of hunger . Hunger immediately declined following meal consumption, reaching nadir levels 15 minutes post-prandially regardless of meal type. However, within 60 minutes after S and L ingestion, hunger began to progressively increase but remained lower at every time point in the S-MRP compared to the L (p < 0.05; Fig. 1). At 4-hour post-meal ingestion, hunger was 14 ± 10 % higher than fasting with the L-MRP; whereas hunger remained below fasting with the S-MRP by 45 ± 19 %.
Read also: Risks of Liquid Diets
Considerations When Choosing Liquid Diet Shakes
Consult a Healthcare Professional
Always prioritize your health first. Before starting a liquid diet, speak with your doctor. It’s also important to make sure that your shakes contain all the recommended vitamins and minerals you need. Registered Dietitian Nutritionists (RDN’s) are the perfect resource to pose this question to because they assess the whole individual before making a blanket decision.
Check the Nutritional Content
Look for at least 3 grams (g) of fiber in your shake. The protein content should be higher than or equal to the amount of carbohydrates in the shake.
Be Aware of Allergens
If you have a dairy allergy or lactose intolerance, check labels before purchasing.
Read the Ingredient List Carefully
Look at the ingredients. Ideally the first few ingredients should be fruit or forms of protein (such as milk). If sugar is the first or second ingredient, there's probably a healthier option.
Consider Your Health Conditions
When considering meal replacement options, a few questions come immediately to mind. For instance, do you have any other health conditions that might put you at risk? Do you have diabetes and need to limit your total carbohydrates added sugars? Do you have any conditions that requires a fluid restriction such as chronic kidney disease or congestive heart failure? Are you lactose intolerant? Do you have any food allergies? Do you avoid animal proteins and follow a vegetarian or vegan diet? Patients who have diabetes should choose protein shakes low in sugar (less than 5 grams) and total carbohydrates (e.g.