What Can I Drink When Doing Intermittent Fasting?

You might already know that you can't eat anything during certain times of your fasting diet. But what's less clear is what you can drink when doing intermittent fasting.

Although you have to completely abstain from food during your fasting window, there are several beverage options that won't break your fast. Here's what you can drink while fasting, along with the beverages to avoid and tips to get your intermittent fasting diet started.

Intermittent fasting is more than just not eating. The goal isn't calorie restriction — it's giving your body a break from food so that it can focus its energy on cleansing, rather than digesting.

Your body contains proteins and other structures that constantly become dysfunctional or die, according to the Walter and Eliza Hall Institute of Medical Research (WEHI). This isn't a bad thing — it's a necessary process for optimal health.

Enter a process called autophagy. Autophagy is a form of cellular cleansing where the body marks damaged parts of cells and unused proteins as potentially harmful. Once your body gets this message, the damaged parts are cleared out, according to February 2018 research in ​Obesity​.

However, if autophagy is never initiated, dead or dysfunctional cells can accumulate in the body, which can lead to diseases like lupus, type 1 diabetes and cancer, per the WEHI. Fortunately, fasting can trigger the cleansing process, per the ​Obesity​ research.

There are many different fasting patterns to pick from, but all of them involve eating during specific windows of the day and then abstaining from food otherwise, according to Johns Hopkins Medicine. For instance, the popular 16:8 diet provides an eight-hour eating period followed by 16 hours of fasting.

Now that you understand the basics of fasting diets, you may be wondering what can you drink while fasting. Here's a breakdown:

The best choice is always water, according to Johns Hopkins Medicine. Your water can be plain or carbonated, as long as there's no added sugar.

Staying hydrated helps curb hunger, which may make it easier to stick to your fasting diet, per Johns Hopkins University. There are also other benefits to drinking water, including:

• It can help lubricate your joints
• It can help regulate your body temperature
• It supports digestion
• It flushes waste from the body
• It nourishes your cells

You can drink some types of flavored water while fasting, including carbonated or seltzer water.

But make sure you're diligent about reading labels. While true seltzer water doesn't have any added sweeteners, some flavored water drinks do, so read the ingredient lists and avoid anything with added sugar or artificial sweeteners. Even water flavored with natural no-calorie sweeteners like stevia may kick-start a sugar craving, per Harvard Health Publishing, which may make it harder for you to stick to your fast.

Accordingly, choose plain seltzer water or waters with natural flavors or fruit essences only. You can even do it yourself by adding fresh lemon to a glass of water.

You can also add flavor to your water by brewing a cup of tea during a fasting session, according to Johns Hopkins Medicine. Just make sure not to add any sugar, milk or cream to your cup.

Black coffee won't break your fast or take you out of ketosis. In fact, according to a January 2017 review in the ​Journal of Basic and Clinical Physiology and Pharmacology​, caffeine may even increase your metabolism, which could help promote weight loss. Black coffee also helps curb your appetite, which can make getting through your fast more manageable.

But it's important that it's black. If you add cream, milk and/or sugar to your coffee, you'll break your fast.

And although black coffee is OK to drink while intermittent fasting, try not to go overboard. Too much coffee can leave you feeling jittery or irritable, especially if you're sensitive to caffeine, per the Mayo Clinic. Drinking coffee late in the day can also affect the quality of your sleep.

Diluting a small amount of apple cider vinegar in a cup of water won't break your fast. In fact, it might actually be a good idea — the tonic may help support weight loss and lower blood sugar, according to the Cleveland Clinic. However, more research is needed to better establish apple cider vinegar's effect on weight.

Make sure to dilute it in water before drinking it, though. Apple cider vinegar is highly acidic and can irritate your throat if you drink it straight, per the Mayo Clinic.

Because of the massive amount of sugar that Americans eat on average, many people have become dependent on glucose for energy. When you eat a lot of sugar and that sugar isn't utilized for energy, your body breaks it down and eventually stores it as body fat, per UC Berkeley. In addition, the refined sugar found in most beverages digests quickly, spiking both your blood sugar and your insulin levels.

Sugar is also addictive. Indeed, a July 2013 review in ​Current Opinion in Clinical Nutrition and Metabolic Care​ found that sugar and sweetened beverages and foods induce reward and craving responses in the brain that are comparable to the responses triggered by addictive drugs, which continue the cycle.

As a result, it's best to avoid sugary drinks that can break a fast, including:

• Soda
• Lemonade
• Fruit juices
• Gatorade
• Sweetened iced tea
• Kombucha

During your fasting window, you can drink as many of the approved beverages as you want, but you can't eat anything. Eating provides calories and starts digestion, both of which break your fast.

But when your fasting period ends and you enter your feeding window, it's best to make food choices that keep your blood sugar levels stable. Although there's no specific dietary recommendation when intermittent fasting, many people choose to combine it with a low-carb, high-fat ketogenic diet.

Keto-friendly foods include:

• Nuts
• Seeds
• Vegetables
• Avocado
• Olives
• Meat
• Fish

At the same time, it's best to limit or avoid high-carb or high-sugar foods like:

• Whole grains like whole-wheat bread, oatmeal and brown rice
• Most fruits
• Starchy vegetables like potatoes
• Sugary, processed foods like baked goods or soda

Intermittent fasting isn't a regimen built around limiting calories (although it's possible that your calorie intake will be restricted naturally because you're going a period of time without eating), but it can promote weight loss in other ways.

For one, fasting gives your metabolism an overhaul, according to the Harvard T.H. Chan School of Public Health. It works on the same principles as a ketogenic diet. By restricting food (and carbohydrates), you'll switch your body from burning glucose for energy to burning stored body fat.

According to an October 2014 study in ​Translational Research​, intermittent fasting can reduce your weight by 3 to 8 percent over three to 24 weeks. A December 2015 review in ​Molecular and Cellular Endocrinology​ echoed those results by finding that, on average, participants following a fasting diet lost between 7 and 11 pounds in 10 weeks.

So, what's the ideal way to design an intermittent fasting plan? It depends on your schedule and what works best for you, but a good template to start is:

• Start your day off with a glass of water. Your body is made up of around 60 percent water, and every one of your cells needs it to function, per the U.S. Geological Survey.
• After your water, have a cup of plain black coffee or tea if you'd like.
• Continue fasting for your chosen length of time.
• When it's time to eat, keep your intake of sugar and other carbohydrates low and eat plenty of nutritious, fiber-rich foods.
• Continue drinking water throughout the course of the day until you reach your goal intake.