Liquid diet, most commonly in the forms of juice mocktails and clear broth, has become one of the most popular fads over the years, claiming to detoxify the body and promote weight loss.
It’s a process that involves exclusive liquid sustenance for a period of time, often for a week, to “reset” the gut, improve digestion, and eventually lead to weight loss.
But is a liquid diet actually effective? And more importantly, is it safe?
According to a 2025 Northwestern University study published on Nutrients, undergoing a juice-only diet, regardless of whether it’s composed of only vegetables and fruits, may do more harm than good for your health, even for a short period.
The study found that a juice-only diet can alter the body’s microbiome, increasing pro-inflammatory bacteria and even showing potential links to “cognitive decline.”
Dr. Jose Sollano, Jr., a gastroenterologist and medical director at the Healthway Cancer Care Hospital, said “juice or bone broth ‘detoxes’ are not medically necessary" for most healthy individuals.
“The body already has highly effective systems, especially the liver, kidneys, digestive tract, and lungs, that naturally process and remove waste,” he said.
Similarly, Dr. Macgerald Cueto, a medical doctor at Marie France, emphasized that the body’s natural detoxification process “kicks in when it is necessary,” making “radical and unorthodox detox procedures” unnecessary for most people.
The doctors said claims about liquid cleanses flushing out toxins, boosting energy, improving digestion, and promoting weight loss lack adequate scientific evidence.
“There is limited strong data to support these claims,” Cueto said.
What happens in the body during a liquid diet?
During a liquid cleanse, the body undergoes significant metabolic changes due to very low-calorie intake.
“During extended fasting periods, your body switches from using carbohydrates as its primary fuel source to burning stored fat and producing ketone bodies,” Cueto explained.
“This metabolic switch is one of the most substantial physiological changes that occurs, and research confirms it happens when caloric intake is severely restricted, like in juice fasting protocols,” he added.
But these metabolic changes are “temporary adaptations," Cueto said.
Meanwhile, gastroenterologist Dr. Rei Joseph Prieto said juice cleanses often lead to “fatigue, hunger, and temporary changes in blood sugar levels,” while also reducing protein and fiber intake.
While bone broth cleanses differ from juice detox by providing some nutrients, these are “still nutritionally incomplete if used as a meal replacement for several days.”
“From a clinical standpoint, one of the most important things we look at in Healthway Cancer Care Hospital is adequacy, whether a patient is getting enough protein, fiber, and micronutrients to support recovery, immunity, and overall function,” Prieto said. “Many of these cleanses fall short of that standard.”
Without medical supervision, undergoing a liquid diet comes with harmful risks.
“The most common risks include nutritional imbalance, dehydration, fatigue, and fluctuations in blood sugar levels,” Sollano said.
In addition, Cueto also pointed out that “prolonged medically unsupervised liquid cleanse can lead to malnutrition, particularly due to lack of protein, essential minerals for bone health, and fiber,” to name a few.
He added a liquid diet can disrupt hormones, affecting “testosterone and androgen levels,” as well as “cortisol, insulin, and other regulatory hormones essential for normal bodily function.”
Liquid diet for weight loss
Some people see a liquid diet as a “shortcut” to rapid weight loss, but doctors agree the results are misleading and unsustainable, making it not an ideal long-term solution for those looking to lose weight.
“Most of the weight loss during a cleanse is temporary and largely related to water loss and depletion of glycogen stores,” said gastroenterologist Dr. Mark Paolo Chatto.
“Restrictive diets do not address the long-term lifestyle habits that influence weight management,” he added.
Cueto explained some fat loss may occur after a few days, but the body eventually adapts.
“This plateau of weight loss is a natural body response to protect itself from its perceived state of famine,” he said, adding without “lifestyle modifications, physical activity, positive social relationships, behavioral changes, and sensible nutrition,” people are likely to regain the weight they have lost during their liquid diet period.
Who should avoid a liquid diet?
Sollano advised that pregnant or breastfeeding women, children and adolescents, individuals with diabetes, kidney disease, or gastrointestinal disorders, and those undergoing medical treatment should avoid liquid diets altogether.
For those not in these groups but still curious to try a liquid diet, doctors recommend caution.
“Seeking advice from a medical or nutritional professional is the first step,” Cueto said.
If pursued, he advises limiting a liquid diet to “one to three days at most” and paying close attention to how the body responds.
“The key is not to overdo it,” he added. “Listen and observe your body.”
A better way to “reset”
Ultimately, doctors emphasize that long-term health does not come from short-term restriction.
“A healthier reset usually involves returning to balanced eating rather than restricting food intake,” Sollano said.
“This includes prioritizing whole foods, vegetables, fruits, lean protein, whole grains, hydration, and regular physical activity,” he added.
Instead of cleansing through a liquid diet, it is recommended to maintain sustainable habits such as balanced nutrition, regular physical activity, adequate sleep, and stress management.
“These sustainable habits support the body’s natural detoxification systems far more effectively than short-term cleansing diets,” Sollano said.
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