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How long can you do a juice fast?

A juice fast, also known as a juice cleanse or juice detox, involves consuming only fresh fruit and vegetable juices for a period of time. Some people do juice fasts for just a few days while others go on juice fasts for weeks at a time. But how long can you safely fast on just juices? Here’s a look at the different durations of juice fasts and what you need to know before trying one.

What is a Juice Fast?

A juice fast means abstaining from solid food and only drinking fresh juices made from fruits, vegetables and sometimes nuts/seeds. The goal is to flood the body with nutrients while giving the digestive system a rest. Juicing extracts the juices from produce while leaving behind the fiber, allowing the nutrients to be rapidly absorbed into your system.

Most juice fasts also involve abstaining from coffee, tea, alcohol and any other caloric beverages. Only water and herbal teas are consumed in addition to the fresh juices. Some people choose to do a juice fast to lose weight, detoxify their bodies or reset unhealthy eating habits. Others use juice fasts to give their digestive system a break or help eliminate sugar and processed foods from their diet.

Benefits of a Juice Fast

There are several proposed benefits to doing a juice fast including:

  • Rapid absorption of nutrients – Juicing condenses fruits and veggies into an easy-to-digest format.
  • Weight loss – By abstaining from solid foods, you slash your calorie intake which may lead to weight loss.
  • Toxin removal – With no solid foods, your body can dedicate energy to eliminating toxins stored in fat cells.
  • Lower cholesterol – Some juices, like green juices, may contribute to lower cholesterol.
  • Clearer skin – Elimination of inflammatory foods may improve acne and skin conditions.
  • Boosted energy – Flood of nutrients gives you natural energy boost.
  • Improved focus – Some people report improved mental clarity from juice fasts.
  • Better sleep – Juices high in magnesium and potassium can improve sleep quality.
  • Reduced inflammation – Fast gives digestive system a rest which helps reduce inflammation.
  • Reset eating habits – Taking a break from solid foods can help reset unhealthy eating patterns.

However, there is limited scientific evidence to support these claims. More research is needed to confirm the specific benefits of juice fasts.

Duration of a Juice Fast

Juice fasts can range from a few days to a few weeks in duration. Here are some of the most common lengths of time for juice fasting:

  • 24-72 hours – The shortest juice fasts last just 1-3 days. This is a good starting point if you’re new to juice fasting.
  • 3-5 days – A juice fast lasting 3-5 days gives your body a chance to reset without being too extreme.
  • 1 week – One full week on a juice fast allows for more significant toxin removal and weight loss.
  • 10 days – 10 days of juice fasting is considered safe for most healthy adults. Great for detoxing.
  • 2 weeks – A 2 week juice fast is the maximum duration typically recommended.Should only be done occasionally.
  • 21-30 days – Juice fasting for 3 weeks or longer is not recommended due to potential for nutrient deficiencies and other risks.

In general, the longer you juice fast the greater the risk of side effects. Shorter juice fasts of 3-5 days are considered safest, especially for beginners.

Is a Long Juice Fast Safe?

Juice fasts lasting more than two weeks are not typically recommended. Here are some of the risks and side effects associated with extended juice fasting:

  • Nutrient deficiencies – Long-term fasts may lead to deficiencies in protein, fatty acids, vitamin B12, iron, calcium and other nutrients. Nutrient-dense juices may help counteract this.
  • Muscle loss – Catabolism and muscle wasting may occur after several weeks without protein intake.
  • Fatigue – Lack of calories can lead to tiredness, dizziness and low energy.
  • Hypoglycemia – Low blood sugar symptoms like shakiness, anxiety and lightheadedness.
  • Dehydration – Without fiber, stools loose water content which could lead to dehydration.
  • Electrolyte imbalances – Sodium, potassium and magnesium levels may become depleted.
  • Constipation – Lack of fiber makes it difficult to have bowel movements.
  • Headaches – From dehydration, caffeine withdrawal, salt imbalance, etc.
  • Irritability – Food cravings combined with low energy can make you cranky.

To reduce these risks, be sure to drink electrolyte-rich juices and herbal teas during an extended fast. Taking a fiber supplement or doing occasional colonics can also minimize constipation issues.

Who Should Not Juice Fast

Juice fasts are not suitable for everyone. The following individuals should avoid prolonged juice fasts:

  • Children under 18
  • Pregnant or breastfeeding women
  • Those with eating disorders
  • People who are underweight
  • Individuals with gout
  • Anyone with diabetes or blood sugar issues
  • People who take medications that require food
  • Those with kidney disease or renal failure
  • Individuals with liver disease
  • Anyone with cancer
  • People who have had an organ transplant
  • Those with thyroid issues
  • Individuals with autoimmune diseases
  • People with gastrointestinal issues like ulcers or IBS

Pregnant and breastfeeding women have increased calorie and nutrient needs to support a growing baby. Those with medical conditions may have special dietary requirements as well. For these groups, even short 24-48 hour juice fasts should be undertaken cautiously under medical supervision.

How to Start a Juice Fast

If you’re generally healthy, here are some tips for safely starting a juice fast:

  • Talk to your doctor – Get medical clearance, especially if you take medications or have any health conditions.
  • Pick your duration – Start with 24-72 hours, building up to 3-5 days. Only do longer fasts occasionally.
  • Plan your juices – Get ingredients for nutrient-dense vegetable, fruit, herb, nut and seed juices.
  • Stock up on supplies – Get a juicer or blender and reusable water bottle.
  • Cut out caffeine – Eliminate coffee, energy drinks, etc. a few days beforehand to prevent withdrawals.
  • Eat lightly – Stick to light whole foods leading up to the fast to prepare your body.
  • Try intermittent fasting – Gradually restrict eating window to ease into fasting.
  • Rest and relax – Plan for extra rest and light activity during the fast.
  • Listen to your body – Stop the fast if you feel faint, extremely fatigued or unwell.

Easing into a fast and taking precautions can help minimize side effects. Be sure to stay hydrated by drinking herbal tea, water with lemon and mineral-rich juices.

How to Break a Juice Fast

It’s important to properly break your fast by slowly reintroducing solid foods. Here are some tips for ending a juice fast:

  • Introduce foods gradually over 2-3 days
  • Start with broths, light soups and smoothies
  • Move on to raw fruits and steamed veggies
  • Then introduce cooked whole grains, legumes, eggs, etc.
  • Limit fats, oils, meat and dairy initially
  • Keep processed foods, sugary foods and alcohol to a minimum
  • Chew your food extremely well and eat slowly
  • If you overate, resume drinking juices to give digestion a break
  • Expect some bloating and digestive discomfort initially

A gradual refeeding process can minimize issues when you transition back to solid food. This allows your body and digestive system to readjust at a comfortable pace.

Should You Juice Fast?

Short juice fasts of 24-72 hours can be safe for most healthy adults and provide benefits including improved energy, reduced inflammation and weight loss. Moderate juice fasts of 3-5 days give your body a chance to recharge and reset without taking extreme measures.

However, longer juice fasts lasting 1-2 weeks come with increased risks and side effects. Children, pregnant women, the elderly and those with medical conditions should avoid prolonged juice fasting.

While juice fasts may seem like a quick fix, they aren’t sustainable for the long-term. Consuming a wholesome, balanced diet focused on fresh foods is a better strategy for supporting your health over a lifetime.

The Bottom Line

How long should you juice fast? Here are some general guidelines based on the current evidence:

Duration Benefits Downsides Who it’s for
24-72 hours Improved energy, reduced inflammation, appetite reset Hunger, caffeine withdrawal headaches Healthy adults
3-5 days Toxin removal, weight loss, reduced bloating Potential mild fatigue and irritability Healthy adults
1 week Significant weight loss, detoxification Increased fatigue, nutrient deficiencies Healthy adults periodically
10 days Major detoxification, body reset Muscle loss risk, severe fatigue Healthy adults periodically
2+ weeks Extreme detoxification High risk of deficiencies, muscle loss, severe side effects Not recommended

While longer fasts may seem more beneficial, shorter 1-5 day juice fasts are safer and provide ample benefits, especially when done intermittently. Be sure to consult your healthcare provider before attempting a juice fast.