What Can You Drink While Fasting – The Picks That Help Your Diet

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By Thomas Youngerman

Reviewed by Juliana Tamayo, MS, RDN - Last Updated

What You Can Drink While Intermittent Fasting - Recommended Drinks By Experts

Timothy Ferris of the 4-Hour Workweek and 4-Hour Body fame is also a favorite author. In one of his latest works, Tools of Titans, he interviews billionaires, icons, and world-class performers, such as Arnold, Kevin Costner, Jamie Foxx, Jack Dorsey, Laird Hamilton, Gabby Reese, and Charles Poliquin to learn the habits and routines that have made them successful. The book is a compilation of what Ferris refers to as low-hanging fruit, or PEDs (Performance Enhancing Details), small things which done consistently become the big things. Two of these PEDs were of particular interest:

  1. More than 80% of the interviewees practice some form of daily mindfulness or meditation. 
  2. A number of interviewees never eat breakfast.

Although an advocate of mindfulness and meditation, that is fodder for another article. What intrigued me was the surprising number of interviewees who didn’t eat breakfast. Interviewees who didn’t break their overnight fast in the morning. Ferris is no stranger to Intermittent Fasting; in fact, he is a major proponent of the eating pattern. Yet, many interviewees didn’t refer to skipping their morning meal as fasting, just a habit of saving time in the morning and putting it to more productive use.

Intermittent fasting has become wildly popular within the world of fitness and health, as exemplified by these experts’ interviews. But, while the rules for eating may be pretty clear, many may find themselves wondering, what can you drink while fasting? We did the research are ready to bring you some top information and choices when it comes to this question. So, without further ado, let’s dive into the world of fasting and find out what you can and cannot drink during that time!

Fasting And Intermittent Fasting

Fasting – Gaining Popularity and Advocates

Regardless of the motivation in the above examples, once a person abstains from eating for an extended period, minimally twelve hours, a physiological change occurs, triggering a metabolic response, which is proven effective in weight management. Google any of the names Ferris interviewed and let us know how many would be considered overweight. Or google celebrities who practice intermittent fasting. In my search, the first article that appeared featured Jack Dorsey, CEO of Twitter, a Ferris interviewee. He was followed by a group of Hollywood A-Listers, all IF practitioners, all in excellent health. 

Why the increasing popularity of Intermittent Fasting? Because it works! As we go on, we’ll explain what happens to your body while fasting, explore several different IF strategies of eating patterns, and combining IF with other diets, and do a deep dive into what drinks you should and should not consume during fasting to maintain a fasted state and stay in ketosis. Intermittent fasting can provide a plethora of benefits if you know how to follow this diet and stick with it.

Intermittent Fasting and Triggering the Metabolic Switch

Researchers have studied the effects of calorie restriction since the 1930s when a Cornell scientist discovered that rats on a calorie restriction (CR) diet experienced certain health benefits, including extended lifespan. A favored area of research is CR mimetics, a search for compounds that may mimic the CR’s effects. Intermittent fasting (an eating pattern) and the Keto Diet are two strategies that produce a similar physiological response to a strict calorie restriction diet. 

CR triggers a physiological response that creates changes in the body’s metabolism. At the cellular level, autophagy is increased, the repair and recycling of senescent cells. Oxidative damage from free radicals and chronic inflammation are both reduced, important, as both processes play a role in the onset of age-related diseases. When in a calorie-restricted state, your body flips the “metabolic switch” from glucose to fatty acid-derived ketones for your primary fuel. 

Normally blood glucose provides the body with energy through glycolysis. During CR, glycogen stores in the liver and skeletal muscle are depleted, and the body converts to using energy stores from adipose (fat) tissue and protein stores. This change in metabolism requires the conversion of free fatty acids and glycerol into ketone bodies and glucose through ketogenesis. 

Many of you will recognize these changes as those sought while on a ketogenic diet. Studies of intermittent fasting, even without calorie restriction, produce similar metabolic responses. In short, during intermittent fasting and keto, your body exhausts its sugar stores and starts burning fat as your primary source of energy.

Intermittent Fasting – An Eating Pattern

During a fast your focus is when you abstain and when you eat (your eating window) and not on what you eat. When practicing IF, there is no need to count calories or intentionally restrict your caloric intake; however, most people consume fewer calories as they eat fewer meals and do less snacking during the day. Some people do overeat during their feeding window initially, but this lessens and becomes a non-issue over time. 

Intermittent fasting is not a diet per se; rather, it is an eating pattern with fasting periods, a minimum of twelve hours to achieve a fasted state, a period for eating, and then cycling back and forth. There are several variations to IF, including the 16:8, the fast five (abstain for nineteen hours and eat during the fast five-hour window), the 12:12, and alternate-day fasting, to name a few. The 16:8 or the 18:6 are popular strategies as primarily they require you simply skip breakfast and have your first meal of the day either 16 or 18 hours after dinner. Now, think back to the Ferris interviewees, were they not practicing a form of IF?

Consider trying IF and follow a ketogenic or low-carbohydrate diet during your eating window for accelerated weight loss. Want to see results even faster? Add a training program; the synergistic effect will help you maintain lean muscle mass while reducing body fat. 

Fasting Time

Acceptable Drinks to Stay in Ketosis – and Those that Will End Your Fast

Hopefully, the above has illustrated the role of fasting to achieve ketosis. Once your body is producing ketones, and you are in a ketosis state, the last thing you want to do is eat or drink something that will unintentionally end your fast. The simplest rule of thumb when considering a drink while fasting is nothing that will add calories!


We segment drinks in this section into two broad groups, liquids you usually drink throughout the day, think coffee, tea, water, and lemonade, and dietary supplement products such as protein shakes, pre-workout drinks, BCAAs, etc. 

Normal, Everyday Liquids

You normally get about 20% – 30% of your fluids from the foods you eat, so when fasting, you need to increase your intake of liquids to avoid becoming dehydrated. Health experts recommend you continue to consume about eight 8-ounce glasses of fluid each day. Keto-dry mouth and dehydration can be side effects of ketosis, so staying hydrated is essential. Below we indicate which fluids are acceptable and several that are not to meet your daily requirements:

  • Water – the perfect hydrating solution. Plain tap and carbonated water without added sweeteners or flavoring are acceptable. Adding a pinch of Himalayan salt will also help replace electrolytes lost during a fast. Other popular add-ins, lemon, cucumber, and a small amount of apple cider vinegar. 
  • Coffee and tea – both are acceptable, sans the added sugar, cream, or milk. No caramel macchiatos or green tea frappuccinos.
  • Bone broth – this one is a slippery slope; however, we recommend you reserve it for consumption only during your feeding window. Bone broth contains calories, protein, and fats -Ancient Nutrition from Dr. Axe contains 80 calories and 20 grams of protein, sufficient to end your fast and kick you out of ketosis. If you choose to imbibe – limit yourself to a tiny amount.
  • Milk – due to the natural sugars and protein in milk, it should be avoided while fasting. 
  • Soda and diet soda – Sweetened soft drinks are loaded with calories, so that is a definite “no go.” Many diet sodas are technically “calorie-free,” however, we suggest avoiding them while fasting as the artificial sweeteners may trigger an insulin response.
  • Alcoholic Beverages – no beer, wine, or spirits during your fast and in moderation at other times. 

Liquid Dietary Supplements While Fasting

The right dietary supplements, taken at the right time while intermittent fasting can prevent nutrient deficiencies, accelerate health benefits, and help you achieve your body composition objectives. As a general rule of thumb, liquid supplements are acceptable during your fast provided there are no added calories. When considering a liquid supplement for use while fasting, it is important to scrutinize the Nutrition or Supplement Facts panel to determine the composition, checking for calories, carbohydrates, added sugars, and artificial sweeteners. 


Below we indicate which liquid supplements should be taken during your fast and those best left for your eating window:

  • Protein Powders – Only during your eating window. A protein shake during your fast triggers an insulin response, telling your body the fast is over. Remember that excess protein, even during your eating window, converts to glucose for those on keto. 
  • Pre-Workout and Energy Drinks – Products to be taken only during your feeding period due to the added sugars, artificial sweeteners, and possibly BCAAs. 
  • Creatine – if taken by itself, creatine is probably okay during a fast; however, most people get their creatine in a pre-workout which also contains calories and artificial sweeteners. 
  • Caffeine – obviously acceptable provided there are no added calories. 
  • BCAAs – This is another tricky area. Some nutritionists suggest an unsweetened BCAA drink while fasting to supply the body with aminos to avoid muscle wasting. However, the leucine in a BCAA will trigger an insulin response, so best to save the BCAAs or Essential Aminos found in pre-, intra- and post-workout drinks for use during your eating window. 
  • Electrolytes – Replacing electrolytes lost during a fast such as potassium, sodium, and calcium is essential. A liquid electrolyte drink is acceptable when fasting, provided there are no sweeteners, or added calories.  
  • Liquid Healthy fats such as Omegas or Fish Oil from Nordic Naturals or Carlson Labs are minimally acceptable. They are typically very low in calories (with all calories coming from fat) and small serving sizes. However, omegas are more easily absorbed by the body with food, so whenever possible, delay until your feeding window.
  • Exogenous Ketones – BHB (Beta-hydroxybutyrate) are often delivered via capsule; however, there are powdered varieties to create a liquid. Your body is producing ketones for fuel while in ketosis, so supplementing with BHB salts while fasting is acceptable, as always, provided there are no additional calories from other sources.
  • MCT Oils (Medium Chain Triglycerides) – MCT oil is not likely to trigger an insulin response and may actually promote ketosis. However, we recommend consuming only a minimal amount while fasting and taking the remainder of your daily requirement during an eating period.

Drinks for fasting

In Summary: What You Can Drink While Fasting

Water is your best hydration option while fasting. Some fasts require water to be your only liquid. A pinch of Himalayan salt, cucumber, lemon, or apple cider vinegar can help offset the boredom, and each has additional benefits. 

Fasting creates certain deficiencies, so supplementation should play an essential role in meeting minimal requirements for nutrients. Our review addresses liquids only; however, we recommend several other supplements while fasting, such as a good multivitamin/mineral, pre-and probiotics, and ZMA (zinc, magnesium, and vitamin B6). Each of these are acceptable during a fast, as always, with the caveat, no additional calories. 

Drinks While Fasting

There are several other supplements we recommend for those who take our advice and add a training program to accelerate your fasting and diet results. These supplements should only be taken during your eating window: Protein, Whey and/or Casein, and Beta-Alanine, Nitric Oxide Boosters, BCAAS, and L-Glutamine, typically found in a pre- or post-workout. There are quite a few keto-friendly versions of these supplements available on the market as well, such as Biochem Plant Protein and Orgain Keto Collagen Protein.

When fasting, you need to be mindful of what you drink and when you drink. The wrong liquid at the wrong time can sabotage your results, break your fast, and exit ketosis. Remember, when in doubt, refer to the Supplement Facts and Nutrition Panel – if it contains additional calories, carbs, or artificial sweeteners, best to wait until your feeding window.

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Thomas Youngerman

Thomas Youngerman is an entrepreneur and author in the health and wellness space with extensive experience in the supplement industry. He has owned multiple sports nutrition stores and served as the Category Manager and Director of Business Development for a regional chain of nutrition stores. Thomas created a successful line of men’s healthy aging supplements that was distributed in GNC, The Vitamin Shoppe, and Kroger, and later sold to a West Coast corporation. Thomas was previously a certified nutrition coach. He has a strong understanding of nutrition, supplement formulations, DSHEA, cGMP, and FDA regulations.