Can I drink grapefruit juice when fasting?

Intermittent fasting has become an increasingly popular way to lose weight, improve health, and simplify eating habits. During fasting periods, only water, black coffee, and tea are typically allowed. But some people wonder if they can also drink grapefruit juice during their fasting window. This article reviews whether grapefruit juice is suitable for intermittent fasting.

What is intermittent fasting?

Intermittent fasting involves cycling between periods of fasting and eating. Rather than restrict what foods you eat, it controls when you eat them. It’s an eating pattern that tells you when to eat, not what to eat. There are several popular intermittent fasting methods, including:

  • 16/8 method: Fast for 16 hours per day and restrict eating to an 8-hour window.
  • 5:2 diet: Eat normally 5 days a week but reduce calorie intake to 500–600 calories on 2 nonconsecutive days.
  • Alternate day fasting: Fast every other day, limiting intake to about 500 calories on fasting days.
  • The Warrior diet: Eat small amounts of raw fruits and vegetables during the day and one large meal at night.
  • Eat-stop-eat: Fast for 24 hours once or twice per week.

No matter the protocol, the purpose of intermittent fasting is to limit food intake to specific time periods to take advantage of the health benefits of fasting.

Benefits of intermittent fasting

Research shows that intermittent fasting may:

  • Enhance weight loss
  • Improve blood sugar control
  • Increase longevity
  • Protect brain health
  • Reduce inflammation

The benefits are thought to stem from activating cellular repair processes and changing how your cells use energy during fasting periods.

Guidelines for fasting

To get the most out of intermittent fasting, it’s best to stick to just water, black coffee, and tea during fasting periods. Here are some guidelines on what drinks are allowed:

Allowed Not allowed
Water Juice
Unsweetened tea Milk
Black coffee Soda
Clear broth Alcohol
Plain sparkling water Sweetened beverages

Drinks like juice, milk, alcohol, and sweetened beverages are restricted during fasting periods because they provide calories and nutrients that can interfere with the benefits of fasting.

Can you drink grapefruit juice while fasting?

Grapefruit juice contains calories and sugar, so it does not comply with standard intermittent fasting guidelines. A 1-cup (240-ml) serving of unsweetened grapefruit juice contains around 100 calories.

Drinking grapefruit juice could potentially prevent your body from entering into a fasted state. Most experts advise against drinking any type of juice during your fasting window.

That said, some modified fasting regimens do allow for a limited number of calories, usually around 500 per day. In that case, a small glass of grapefruit juice may be acceptable.

If you want to drink grapefruit juice but also practice intermittent fasting, consider these tips:

  • Have just 2–4 oz (60–120 ml) of unsweetened grapefruit juice to limit calorie intake.
  • Drink it toward the end of your fast when hunger is strongest.
  • Consider doing alternate day fasting rather than daily 16-hour fasts.
  • Stick to water, black coffee, and tea on stricter fasting days.

Other drinks to try

If you want to avoid grapefruit juice but still enjoy a flavorful, low-calorie drink during your fast, here are some better options:

Drink Benefits
Sparkling water Hydrating, no calories
Green tea Antioxidants, metabolism boost
Black coffee Appetite suppressing, energizing
Herbal tea Soothing, variety of flavors
Diluted apple cider vinegar Supports blood sugar
Bone broth Hydrating, electrolytes

These drinks can make fasting more pleasant without adding significant calories. Herbal teas like mint, chamomile, and hibiscus provide flavor without sweeteners. Sparkling water can mimic the carbonation of soda without sugar.

Should you drink grapefruit juice for other benefits?

Although grapefruit juice may not fit into an intermittent fasting plan, it does offer some unique health benefits. Grapefruit juice contains:

  • Vitamin C: Important for immunity and collagen production.
  • Potassium: Helps regulate blood pressure.
  • Antioxidants like lycopene: Reduce inflammation and oxidative damage.
  • Naringin: A flavonoid that may support weight loss.

In particular, grapefruit juice has become known for its potential to boost weight loss. Some research indicates grapefruit juice may:

  • Increase feelings of fullness
  • Help burn fat
  • Reduce insulin resistance
  • Lower cholesterol

So while grapefruit juice may not be suitable for fasting, it can still be part of a healthy diet focused on weight management.

Should you drink grapefruit juice with medications?

If you take certain medications, grapefruit juice should be avoided altogether or consumed only in very small amounts. Grapefruit juice interacts with enzymes that metabolize common medications.

Drinking grapefruit juice while on these medications can cause elevated drug levels in your blood, potentially increasing side effects.

Medications known to interact with grapefruit juice include:

  • Statins like atorvastatin (Lipitor) and simvastatin (Zocor)
  • Immunosuppressants like cyclosporine
  • Benzodiazepines like diazepam (Valium)
  • Some blood pressure medications
  • Some antidepressants

Check with your doctor or pharmacist to see if any of your medications may interact with grapefruit juice.

The bottom line

For most people doing intermittent fasting, plain water is the best bet during fasting periods. Drinking calorie-containing beverages like grapefruit juice can inhibit some of the benefits.

However, for fasts that allow up to 500 calories per day, a small glass of unsweetened grapefruit juice is unlikely to negatively impact your fast. Just be mindful of medication interactions.

Focus on hydrating drinks like water, sparkling water, black coffee, and tea for stricter fasts. Then drink grapefruit juice and other beverages during your eating window so you can gain the other unique health benefits of grapefruit juice.


While grapefruit juice doesn’t fit perfectly with intermittent fasting guidelines due to its calorie content, it may be a reasonable choice on more flexible fasting regimens that permit a limited number of calories. However, plain water, coffee, and calorie-free beverages remain the best options for purely fasting periods. Outside of your fasting window, taking advantage of grapefruit juice’s health benefits can be part of an overall nutritious diet.

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