Intermittent fasting is the practice of not eating for periods of time, then resuming a normal eating pattern. The theory behind intermittent fasting for weight loss is that your body is taking in fewer calories and will hopefully slow down your metabolism and make you less hungry, according to Harvard Medical School. Even while you're not eating foods, you do have options for what you can drink during intermittent fasting. Always talk with your doctor before beginning a fast to be sure it is safe for you.
The Journal of the Academy of Nutrition and Dietetics outlines several types of intermittent fasting for weight loss. The type of fast you choose will largely determine what you can drink during intermittent fasting.
- Complete alternate day fasting: alternating no energy (fasting) days with eating days
- Modified fasting: Eating 20 to 25 percent of the normal energy intake on fasting days
- Time restricted fasting: Eating within a certain time window and fasting for the remaining hours
Can I Drink Water While Intermittent Fasting?
According to Maggie Moon, MS, RDN, author of The MIND Diet, intermittent fasting takes many forms, but most allow water. In fact, avoiding water for extended periods of time can be dangerous. "It is important to stay hydrated even when fasting," Moon says. "Dehydration can lead to unclear thinking, mood changes, constipation and kidney stones."
If there is some food intake involved during intermittent fasting (e.g. some plans call for around 500 calories per day on calorie restricted days), then Moon recommends about 9 cups of water for women and 12 for men.
But when food intake is restricted during intermittent fasting, more of your hydration will come from plain old water. General recommendations for daily water intake from all food and beverage sources are about 11 cups of water for women, and about 15 cups for men. According to the Centers for Disease Control and Prevention (CDC), most people can stay hydrated by simply letting thirst be their guide.
Can I Drink Tea and Coffee While Intermittent Fasting?
You can drink coffee and tea while fasting. If your fast calls for no energy intake at all, this means you cannot add sugar, cream or milk to your beverages; drink them plain. A 2018 study published in "Trials" on intermittent fasting, allowed black coffee and unsweetened herbal teas for their study participants.
When drinking caffeinated coffee and tea, which can have a mild diuretic effect, ensure you are balancing them out with water. Decaffeinated coffee and teas will ensure that you are getting the hydrating effect needed from your beverage.
Can I Drink Juice While Intermittent Fasting?
Juice is not calorie-free and would not fit in with a no calorie intermittent fasting program. However, according to Moon, nutrients during fasting are important. "I know "fasting" sounds like you aren't eating or drinking anything, but actually, the studies on intermittent fasting often includes some calories on "fasting days," she says.
Her recommendation? One hundred percent juice is one way to provide energy and nutrients during fasting, but it needs to be integrated into a low-calorie plan. From that perspective, high-water, low-calorie foods, such as watermelon, lettuce, and celery may be more satisfying as it gives the fasting person a greater volume of food per calorie.
Other Drinks For Intermittent Fasting
Fruit-infused water is hydrating and may keep the palate more interested on fasting days. One of Moon's favorites is water infused with strawberries, oranges, and mint.
She also recommends unsweetened almond milk, which tends to be low in calories and is fortified with calcium and vitamin D.
Finally, warm, savory clear broths can help make a low-calorie meal feel more satisfying. For example, vegetable, chicken, or beef broth.
The Dangers of Intermittent Fasting
When fasting, it's important to know how your body breaks down energy for fuel. According to the National Institutes of Health, when the body is in a fasting state, it will use up all of the glucose in the body and stored glycogen — which is carbohydrate that is stored in muscle. After those energy stores are gone, the body should start using fat for fuel. Long periods of fasting could be detrimental to the body, so ensure you are having a conversation with a health professional if you are fasting for longer than 24 hours.
In addition, if you have diabetes, are on blood pressure medication or are taking medication for heart disease, fasting may not be right for you.
Educate Yourself on Intermittent Fasting
If you think intermittent fasting may be right for you, seek out a registered dietitian, who can ensure you are getting adequate nutrition on your non-fasting days. Intermittent fasting is not a "one size fits all" approach, as Dr. Steven Gundry explains in his recent podcast all about intermittent fasting, so educate yourself on which fasting method may work with your lifestyle.
- Trials: Intermittent fasting, energy balance and associated health outcomes in adults: study protocol for a randomised controlled trial
- Centers for Disease Control and Prevention: Dietary Reference Intakes: Water, Potassium, Sodium, Chloride, and Sulfate
- Journal of the Academy of Nutrition and Dietetics: Intermittent Fasting and Human Metabolic Health
- Dr. Steven Gundry: Your Brain on Intermittent Fasting
- LIVESTRONG: Intermittent Fasting to Lose Weight
- LIVESTRONG: How many bottles of water should you drink in a day?
- Harvard Medical School: Not so fast: Pros and cons of the newest diet trend
- National Institutes of Health: Calorie Restriction and Fasting Diets: What Do We Know?