If you’re considering adopting a lifestyle that incorporates fasting, it’s normal to have questions as you start planning your approach. You might be wondering what to do to make sure you get the most benefit from fasting and set yourself up for success?

Here’s a comprehensive collection of tips about fasting, including what to do and what not to do, according to the biggest experts in the health and nutrition community who advocate for fasting.

In this article, we explored tips for successful fasting from research scientists, registered dietitians, and some of the most prominent voices in the field of intermittent fasting, including:

 

•  Jason Fung, nephrologist and leading expert on intermittent fasting and low-carb

• Mindy Pelz, chiropractor, educator, and founder of the Family Life Wellness clinic

• Mark Hyman, physician, founder and medical director of The UltraWellness Center

• Peter Attia, longevity-focused physician

• Dave Asprey, best-selling author and the creator of Bulletproof Coffee

• Oz Garcia, nutritionist to the stars and leader on healthy aging

• Daniel Pompa, chiropractor and health evangelist

   

Tip #1: Keep periods of fasting to a scheduled, reasonable time frame.

Intermittent fasting is not a one-size-fits-all lifestyle, and there are several methods you can choose between to see what works best. Many popular approaches either involve fasting for a full day once or twice per week, or include a daily fasting period of 8-16 hours. Registered dietitian Lyndi Cohen says that a 12/12 fasting regimen is optimal, because she’s seen higher incidence of brain fog when fasting periods reach 16 hours or more. [1]

Furthermore, while there are more extreme fasting regimens that may last 36-48 hours, most experts agree that these aren’t sustainable or recommended long-term. In fact, regularly embarking on longer fasting periods may increase your likelihood of side effects like dehydration, headaches, lightheadedness, low blood sugar, irritability, extreme hunger, and even nutrient deficiencies. [2,3] It’s important to speak with your healthcare provider if you’re considering a fast of longer than 24 hours, or a significant change to your diet.

Whichever regimen you choose, experts agree that it’s best to start slowly while your body gets used to the idea of regular fasting. Ease into the routine to decide what schedule works best for you. And when you find that schedule, stick to it.

Dr. Mark Hyman says, “Now, I don’t normally recommend skipping meals – especially breakfast. However, with intermittent fasting, you’re not just whimsically skipping meals, which can mess with your blood sugar and energy levels, you are employing a strategized way to miss meals.” Hyman says that a predictable fasting schedule can help speed metabolism and burn more fat, ideal especially for those who want to lose weight.[4]

When choosing the fasting window duration for you, Dr. Pompa says one strategy is to measure your glucose and ketones in the morning and right before your first meal. “You should see a slight drop in glucose and rise in ketones. This indicates that you are using fat in that specific window of time,” he explains.

And if you don’t see this drop, push your window back. Dr. Pompa says, “Most autophagy starts in 16 hours, so as you decrease your eating window and do more block fasts, your efficiency will begin to improve. Doing this while following a ketogenic diet is key.” [5]

Tip #2: Keep your mind busy.

Fasting or not, it’s not uncommon to think about food the most when you’re actively restraining from eating. “Ask yourself whether the hunger is boredom or actual hunger,” says registered dietitian Eliza Savage. [6] If you conclude that you’re just thinking about food out of boredom, try switching gears into a new task.

Dr. Jason Fung says that, if you find that you have noticeable hunger during fasting periods, there are some natural ways to reduce appetite. These include drinking a cold glass of water, drinking antioxidant-rich green tea to stimulate metabolism, adding cinnamon to beverages for a distracting and satisfying flavor, drinking calorie-free metabolism-boosting coffee, and even adding chia seeds to beverages, which are rich in protein and omega-3 fatty acids that can help curb hunger. [7]

You can also keep your mind busy by doing active things or changing your environment. Going for a walk, meditating, turning on some music, doing an art project, reading a book, taking a bath, or listening to a podcast can all be simple ways of distracting yourself. This is a prime opportunity for implementing some of the ideas on your self-care list.

Tip #3: Stay hydrated, smartly.

While you’ve probably heard of the generic 8×8 rule of hydration- or the idea of drinking 8 glasses of 8 ounces of water per day – individual hydration needs vary. Early signs of dehydration can include dry throat and mouth, headaches, and dizziness.[8]

Dehydration can become dangerous, and may become more of a risk while fasting, especially for longer periods. This is because most people normally get 20-30% of their daily hydration needs met by food they eat, and the salt and electrolytes in their foods help their bodies to hold onto the water they drink.[9,10]

Dr. Jason Fung says that some of the best ways to stay hydrated during fasting periods are with beverages like plain water, teas, or coffee. Bone broth can be made at home using chicken, pork, fish, or beef bones, which offers some nutrients and electrolytes with minimal calories. Bone broth also provides sodium, which can become depleted over longer periods of fasting if you’re only drinking fluids that are salt-free, and can be dangerous.[7]

Dave Asprey recommends a little bit of healthy fat with your hydration during fasting periods in the form of Bulletproof Coffee. Not a lot of calories, but enough to get you through without breaking your fast. He says, “You get to drink coffee with grass-fed butter in the morning before you break your fast at lunchtime. The creamy concoction fills you up and keeps you from feeling deprived.” [11]

Tip #4: Break your fasts gently and intentionally.

Not eating for a prolonged period may result in eating too much, too quickly when the fast is over. Breaking your fast involves reintroducing food to tell your body to switch back to carbohydrates as its primary fuel source instead of fat stores.

Dr. Jason Fung says that the reason many people overeat when breaking their fast isn’t because of an overwhelming sense of hunger, but because of a psychological need to eat. [7]

Still, going overboard with first foods after a fast can cause digestive discomfort, bloating, and even nausea. Experts say that this is more common when someone is totally new to fasting, and not surprisingly is a lesson that’s quickly learned and not often repeated.

Dr. Pompa says that it can take some time for your body to get used to eating after a fast, especially in the beginning. “When breaking a fast, go slowly by eating very soft, easily digestible foods such as berries, soft avocados, and veggies that are steamed or blended. A little coconut oil or olive oil can be good as well, but consume just a little bit at a time,” he suggests.[5]

Other experts recommend gently breaking a fast with a handful of nuts or seeds, a small salad, a piece of toast, or a soup. It may help to finish this small meal and then wait 15-20 minutes before eating again.

Tip #5: Prioritize nutrition.

One of the most common tips for successful fasting is to prioritize healthy eating. “It doesn’t require counting calories, macros, or measuring ketones. You can eat most anything you want between a specific window of time, although most programs recommend eating healthfully when you do eat,” says registered dietitian Sonya Angelone, a spokeswoman for the Academy of Nutrition and Dietetics.[6]

While intermittent fasting focuses less on food, and more on timing, that doesn’t make diet quality any less important. After all, intermittent fasting is designed to improve overall health and lower your risk for chronic disease.

Making healthy food choices is a significant piece to that puzzle. Plus, Oz Garcia says, “The meals that you do consume need to be healthy enough to provide adequate nutrition since you are not eating at other times.” [12]

Whole foods, like lean proteins, fruits, vegetables, grains, nuts, seeds, and legumes are inherently nutrient-dense. Eating periods based on these types of foods benefits your overall health. Foods rich in fiber, protein, complex carbs, and healthy fats can also help your fasting regimen be more successful by keeping your blood sugar steady.

Eating well is equally important while traveling or out of your usual routine. Dr. Mark Hyman says, “Do a little research before you travel. Most cities have a Whole Foods Market or their local version of a natural foods market and most have salad bars… I also like to make a list of restaurants that I want to check out before heading to my destination.” [4] Keep healthy snacks on hand in case you’re unable to find food immediately after a fast, and in case of a hunger emergency.

Fasting isn’t intended to be a restricted diet, either. Dr. Pompa says, “Do not limit calories, but rather restrict eating to a certain window of time.” [5]

Tip #6: Listen to your body.

If you’re new to fasting, you may be hypersensitive to changes in how you feel. While this typically subsides as your body adapts to its new eating pattern, it’s important to stay cognizant of these changes.

Keeping a journal of how you’re feeling, and if you think a change in your eating pattern has anything to do with it, can be helpful for reflection.

If you begin to feel weak, tired, or too fatigued to carry out activities of your daily life, it’s best to speak to your healthcare provider. Seek medical attention immediately if you have unexpected feelings of extreme discomfort or sickness. [2]

Tip #7: Have patience with the process.

Fasting can take some time to adapt to, and it may not go as planned all the time. But Dr. Mindy Pelz says, “There is NO such thing as a failed fast. Every fasting experience makes you stronger and more adapted.” [13]

Don’t be surprised if you learn something new about fasting or your body every day. You can take this information and use it to adjust your regimen as needed, or make improvements for the next day.

You may not feel benefits right away, may be unsure if you’re “doing it right”, or be questioning your routine, but experts agree that it’s important to have patience in the beginning while you adapt.

Tip #8: Consider incorporating supplements.

While most nutrition professionals emphasize whole foods to get most of your nutrients, supplements can also be appropriate and beneficial. [14] Keep in mind that some nutrients are best absorbed when taken with food. For instance, the fat-soluble vitamins A, D, E, and K should be taken during eating periods so they are better absorbed.

Additionally, it may be best to avoid supplements during fasts anyway as not to break your fast unintentionally. For instance, supplements with added sugar or calories may be enough to switch your body out of ketosis before you’re ready.

Some research suggests that people following diets intended for weight loss are at a higher risk for becoming deficient in nutrients like vitamin B12, calcium, and iron. [15] If you’re concerned that your fasting regimen may not be meeting your needs, specific nutrient supplements may be prudent.  Talk to your healthcare provider about whether supplements may be right for you, and what might be most beneficial to specific needs.

Tip #9: Be smart with physical activity.

Most experts agree that you shouldn’t stop physical activity with fasting for shorter periods. However, you also shouldn’t push yourself to be active if you’re not feeling up for it. Do you prefer exercising on an empty stomach, or well-fueled after an eating period?

Dr. Jason Fung encourages people to continue exercise, and says fasting may be optimal to do so due to heightened levels of adrenaline and growth hormone in the body. He says that the body gets the energy it needs for activity from the process of gluconeogenesis, and that the muscles can also use fat stores for energy during longer periods of fasting.[7]

Other good news is that fasting doesn’t seem to negatively affect strength. Dr. Peter Attia advocates for a mix of activities that include resistance training, saying that this is actually key to maintaining muscle mass while fasting.[16]

To optimize your exercise experience while fasting, fuel yourself with healthy foods ahead of time, stay hydrated, and replete electrolytes.

Tip #10: Know that fasting isn’t for everyone.

Keep in mind that while some people adapt to fasting quickly and feel great, it’s not a perfect match for everyone. If you implement the expert tips above and still don’t feel like you’re thriving, don’t force it.

Additionally, people with medical conditions like type 2 diabetes or heart disease, who are pregnant or nursing, have a history of disordered eating or who are underweight, who have challenges with blood pressure or blood sugar management, or who are adolescents, may need to avoid fasting. Experts agree that it’s best to speak to your healthcare provider if you’re uncertain whether intermittent fasting is safe and appropriate for your unique needs.

If you decide to try intermittent fasting, keep these tips in mind to help find the most successful approach for you.