Liquid diets don’t scream fun. If you’ve ever been on one, you know that it’s often bland, boring, and texture-less. And while sticking to a diet of non-solid foods is pretty miserable for most people, they are used for many reasons. Some have even followed a liquid diet for weight loss.
Doctors sometimes prescribe a liquid diet to patients for different medical reasons. “A liquid diet is a specific type of diet that provides all or most of your daily calories from a liquid source,” explains Erin Rossi, RD, LD, with Cleveland Clinic’s Center for Human Nutrition. “Any liquid that can be poured at room temperature or a soft solid that can melt in your mouth and has a smooth texture could be included on this type of diet.”
She adds that liquid diets may be prescribed prior to gastrointestinal surgeries to help prep the body for the procedure or after surgeries of the mouth, throat, or stomach, where liquids can lessen the pain of eating or rubbing against the surgical site.
Post-surgery they can help and allow for healing. “This provides an opportunity for the body to heal, improve hydration, and assess toleration of the liquids before advancing to liquids or foods that are more difficult to digest,” says Melissa Majumdar, RD, CSOWM, LDN, a spokesperson for the Academy of Nutrition and Dietetics.
Liquid diets may also be prescribed in other health situations. “Some doctors use liquid diets when patients are unable or unwilling to eat solid food due to mental health concerns,” adds Rossi.
Meet the experts: Erin Rossi, RD, LD, is a nutritionist with Cleveland Clinic, and she specializes in adult chronic disease management, bariatric nutrition, and weight management.
Melissa Majumdar, RD, CSOWM, is a bariatric coordinator at Emory University Hospital Midtown, and focuses on the care of bariatric surgery patients. She is the chair of the integrated health planning committee for the American Society for Metabolic and Bariatric Surgery.
What are liquid diets for weight loss?
On the other hand, liquid diets are also utilized to lose weight—and quickly. (Liquid diets are also known as fad diets.)
“Liquid diets for weight loss are not recommended, as they are not sustainable or healthy. They lack essential nutrients such as fiber and protein, which are crucial for overall health and well-being,” says Rossi.
A medical liquid diet is short-term and closely supervised by a doctor or dietitian to prevent nutrient deficiencies.
A medically controlled liquid diet is often short-term and closely supervised by a doctor or dietitian to ensure the person following the diet does not become malnourished, she explains.
And FYI: Liquid diets for weight loss generally do not provide long-term results. “Often, patients are discouraged that they have gone through the trouble of following a liquid diet and then lose very little weight or gain any lost weight back as soon as they begin eating food again,” Rossi adds.
Can you lose weight on a liquid diet?
You can definitely lose weight on a liquid diet—up to three to four pounds per week, but the number of pounds you drop will vary depending on your height, weight, nutritional status, and the timeframe of the diet.
“These types of diets typically come with pre-determined structured routines, which can be helpful when reducing calories,” says Rossi. “Long-term, liquid-only diets do not provide sustainable weight loss because when a person drastically reduces their calories, it tends to also slow down their metabolism.”
So, when you stop the liquid diet, weight gain typically happens. You have slowed your metabolism down so much that you then have rebound weight gain. “Those that use a combination of liquid meals and solid meals tend to have more long-lasting weight loss,” Rossi adds.
Does a liquid diet offer any health benefits?
A medically supervised liquid diet can offer some benefits.
“Many surgeons request liquid diets after surgeries to help ease the pain of eating and to relieve some GI discomfort following surgery,” says Rossi. “However, recent research is looking at the effects of lessening liquid-only diets surrounding surgeries with promising outcomes.”
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A liquid diet can also be helpful for those with mental health concerns or physical disabilities who cannot or will not consume solid foods by removing the stressor of eating and improving quality of life.
If the medical team is concerned about a person being able to meet their nutritional needs while on a liquid diet, they will prescribe supplements or nutritional support. “This means they may use a tube for feeding or an IV or central line to get closer to the vitamin, mineral, carbohydrate, fat, and protein needs of that person,” says Majumdar.
What are the risks of following a liquid diet to lose weight?
The downsides of liquid diets are almost all related to missing essential nutrients like vitamin and minerals. “Physical side effects of missing out on these nutrients include hair loss, muscle wasting, dizziness, heart damage, kidney stones or gall stones, fatigue, and constipation,” says Rossi.
One of the worst things about liquid diets is the lack of protein. “Protein is required for healing and repair, so even in a medically supervised liquid diet, a person would be encouraged to meet the body’s protein requirements (typically at least 60 grams protein per day, higher during times of healing) and choose a variety of liquids to meet the body’s macro- and micronutrient requirements,” says Majumdar.
Overall, there are many people who should not go on a liquid diet, including pregnant or breastfeeding individuals and those who take insulin, according to Rossi. And you should always check with a doctor before starting a liquid diet.
What can you eat on a liquid diet?
There are different types of medical liquid diets: clear and full liquid.
- Clear liquid diet: A clear liquid diet consist only of liquids that are see-through and at room temperature, says Rossi. This type of liquid diet includes choices such as gelatin, popsicles, water, broth, coffee or tea, sports drinks, and no-pulp fruit juices.
- Full liquid diet: A full liquid diet includes all of the clear liquid choices, plus milkshakes, strained cream soups, thin cooked cereals (cream of wheat, cream of rice, or grits), pudding, custards, protein shakes, hot chocolate, and all types of milk.
However, weight loss liquid diet foods can vary depending on the program you follow.
“Many commercial programs allow specific protein shakes, smoothies, teas, and drink mixes,” says Rossi. “However, they also typically allow for the above-mentioned clear liquids as well.”
The bottom line: A liquid diet is not a sustainable way to lose weight and you may develop nutritional deficiencies if you follow this eating plan. If you’re still curious, check with your doc before starting one.
Emily Shiffer is a former digital web producer for Men’s Health and Prevention, and is currently a freelancer writer specializing in health, weight loss, and fitness. She is currently based in Pennsylvania and loves all things antiques, cilantro, and American history.