Juice cleanses have gained popularity as a short-term detox diet, where individuals consume only fruit and vegetable juices. Proponents claim that these cleanses can lead to weight loss, clear toxins, and improve skin. While fruits and vegetables are undoubtedly beneficial, the reality of juice cleanses is more complex. There is limited scientific evidence to support these benefits, and some potential risks are associated with juice cleansing.
What is a Juice Cleanse?
A juice cleanse is a type of detox diet that involves consuming only juices from fruits and vegetables for a set period, ranging from one day to a week or even longer. Some plans may involve homemade concoctions with water, lemon, and added spices. The general idea behind detox diets is that harmful toxins from the air, water, and food can affect your health and that detox diets are meant to rid your body of these toxins and restore your health. These diets often involve restrictive eating, such as fasting or drinking only juices, along with the use of supplements, herbs, and sometimes colon cleanses.
Potential Benefits of Juice Cleanses
Juicing for Health
Fruits and vegetables are rich in active compounds that can benefit overall health and help prevent chronic conditions. They are a good source of phenolic compounds, which possess antioxidant, immune-supporting, and antibacterial properties. Fruit juices may also contribute to lowering blood pressure and cholesterol levels.
Juicing for Weight Loss
Juice cleanses may lead to initial weight loss due to calorie restriction. A 2017 study revealed that a 3-day juice-only diet altered gut bacteria in 20 healthy adults, resulting in substantial weight losses that persisted after the study. However, it is crucial to recognize that the participants consumed only 1,310 calories per day, which is below the recommended daily calorie intake for weight maintenance. This caloric deficit could be responsible for the rapid weight loss.
Juicing to 'Detox'
Some detox treatments have shown potential in improving liver detoxification and removing environmental pollutants from the body. However, a 2015 review suggests that clinical studies have flaws in methodology and low participant numbers. Much of the evidence supporting detoxification comes from animal research, which may not be applicable to humans.
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Juicing for Skin Health
Animal studies have suggested that certain compounds in fruits and vegetables may improve skin health. However, further research with human participants is necessary before any conclusions can be drawn.
Risks and Downsides of Juice Cleanses
Nutritional Deficiencies
Most juice cleanses do not provide enough solid food to meet energy needs, leading to increased hunger and energy restrictions. This can cause symptoms such as:
- Tiredness
- Headaches
- Irritability
Moreover, juices have less dietary fiber than whole fruits and vegetables. While some research suggests that less fiber facilitates nutrient absorption, dietary fiber offers numerous health benefits. It promotes blood sugar management, heart health, and gut health and is associated with a reduced risk of colorectal cancer.
Potential Health Risks
Juice cleanses can lead to several health risks, including:
- Weight gain
- Obesity
- Diabetes
- Tooth decay
Increased Risk of Eating Disorders
Juice cleanses may increase the risk of developing unhealthy relationships with food or eating disorders. An obsessive preoccupation with health-promoting foods and an avoidance of foods considered "less healthy" can lead to orthorexia nervosa.
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Unsustainable Weight Loss
While it's possible to lose weight on a juice cleanse, it is likely to be water weight rather than fat. After a few days, you may also start to lose muscle mass, which is crucial for overall health. Rapid weight loss isn’t usually lasting weight loss and could lead to a cycle of yo-yo dieting. Severe caloric restriction is not sustainable for most people and rarely leads to long-term weight loss. In most cases, a person will return to their starting weight quickly once caloric restriction ends.
Low Blood Sugar
Consuming an insufficient number of calories can cause a person to experience symptoms relating to low blood sugar, including fainting, weakness, dehydration, headaches, and hunger.
Malnutrition
A person on a juice cleanse may not consume enough proteins or fats, both of which are crucial to physical health, healing, and brain function. Eliminating food groups for extended periods may also lead to malnourishment.
Dehydration
If a juice cleanse includes laxatives or other methods of bowel stimulation, a person could lose too many nutrients in their stool, leading to dehydration and imbalanced electrolytes.
Kidney Health Concerns
While certain nutrients in fruits and vegetables can support kidney function, some foods are high in oxalate, which can increase the risk of kidney problems when consumed in high quantities. Foods high in oxalate include spinach and beets. People with chronic kidney disease may be at risk of oxalate nephropathy, a condition in which the body cannot excrete enough oxalate, leading to its buildup in kidney tissue and potentially causing kidney failure.
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Alterations in Gut Bacteria
Proponents claim that juice cleanses can alter a person’s gut bacteria. However, research shows that juice-only diets have a limited effect on gut bacteria composition. A small new study shows that consuming only liquids made from fresh-pressed fruits and vegetables - even for just three days - can trigger negative shifts in gut and oral bacteria that are linked to inflammation and cognitive decline. Researchers were surprised by “how rapidly and significantly the oral microbiome changed,” says the senior author, Melinda Ring, MD, a physician at Northwestern Medicine and the director of the Osher Center for Integrative Health at Northwestern University Feinberg School of Medicine in Chicago.
Potential Benefits of the 21-Day Juice Fast Diet (and Why They May Not Last)
By consuming only juice for a week (and very light meals for two additional weeks), you’ll trim your calorie intake considerably. For this reason, weight loss is likely during a 21-day juice fast, according to Houston Methodist. However, Danahy cautions that juice fasting isn’t a healthy or sustainable path to long-term weight loss. “Fruit and vegetable juices have virtually no protein and are very low in calories. While that can promote weight loss, it’s mainly because you’re losing water and muscle,” Danahy says. When you resume your usual eating habits, you’re likely to regain weight lost during a short-term fast, according to the Mayo Clinic.
Danahy says that the claim that a three-week juice fast will “detox” your body also doesn’t hold water. “There is no scientific evidence that a juice diet helps you detox,” Danahy says. According to the University of Rochester Medical Center, your kidneys and liver do that job 24/7, so the best way to remove toxins is to support these organs with a healthy, balanced diet high in whole fruits, vegetables, and other high-fiber foods, and low in salt and added sugars, especially in ultra-processed foods and alcohol. As for the mental and spiritual clarity purported to come from fasting, more scientific evidence is needed.
Risks of the 21-Day Juice Fast Diet
Going on a 21-day juice fast isn’t without risks. Keep these in mind when considering this fad diet.
Nutrient Deficiencies
Though fruits and vegetables have lots of important nutrients, they’re notably lacking in protein, fat, and certain micronutrients like vitamin B12, according to Houston Methodist. Going without these nutrients for too long could lead to deficiencies.
Elevated Blood Sugar
Fruit juice is very high in sugar, which can cause high blood sugar in someone with diabetes or prediabetes, according to Diabetes.co.uk.
Undesirable Changes from Low Fiber
A study published in 2025 found that juice diets lacking in fiber caused harmful changes to oral and gut bacteria after just three days. Meanwhile, low fiber intake could slow down your digestion, causing constipation.
Lack of Scientific Evidence
Scientific evidence doesn’t support juicing’s claim to detoxify the body or individual organs.
Social Isolation
The restrictive nature of a 21-day juice fast could mean three weeks of difficulty socializing over meals. During this time, you might lose out on the pleasure of enjoying food with others.
Alternatives to Juice Cleanses
If you wish to lose or maintain a healthy weight and support your body’s natural processes, consider these alternatives:
- Balanced diet: Eating a balanced diet and staying adequately hydrated are the best ways to maintain a healthy weight and support the body’s removal of toxins.
- Plant-based diets: Based on minimally processed foods, these diets are naturally rich in fruit and vegetables and are associated with reduced body weight. With good planning, a plant-based diet can provide all the nutrients necessary for good health.
- Intermittent fasting: This involves abstaining from eating for limited periods and eating a regular diet at other times. Reviews have linked intermittent fasting with weight loss and improvements in insulin sensitivity.
- Smoothies: One delicious way to get the potential benefits of juicing, plus the natural fiber from these foods is to enjoy fruits and veggies in smoothie form," explains Beaver. Beaver recommends trying to blend your favorite fruits and veggies with some Greek yogurt or soy milk for protein. For a green smoothie, pair kale or spinach with a frozen banana.
Expert Opinions
Frank Sacks, a Professor of Cardiovascular Disease Prevention at the Department of Nutrition, Harvard School of Public Health, suggests that if your goal is weight loss, a detox diet might help you drop a few pounds, but you’ll likely just gain it back. He also states that toxins don’t build up in your liver, kidneys, or any other part of your body, and you’re not going to get rid of them with the latest detox wonder. He suggests that the only type of detox diet that is worthwhile is one that limits processed, high-fat, and sugary foods and replaces them with more whole foods like fruits and vegetables.
Amanda Beaver, a wellness dietitian at Houston Methodist, adds that studies have shown that fruit and vegetable juices can boost levels of important vitamins and antioxidants, including folate, vitamin C, vitamin E, and beta carotene. So, in theory, a juice cleanse is helpful for people who find it hard to eat enough fruits and vegetables. She also advises that anyone with kidney disease should not undergo a juice cleanse.