Fasting can help lose bodyfat, prevent chronic disease, increase longevity and boost productivity. Intermittent fasting (IF) or time-restricted feeding (TRF) are habits that can be extremely beneficial for your health, but can be hard to get started. If you want to start but are worried about feeling too hungry after just a few hours, this guide will help you measure and increase your fasting time without suffering.

Just as you practice short distances before running a full marathon, your body will need training to feel great while fasting. Instead of just stopping eating for a whole day, try extending your eating window by just an hour at a time. Just like your body is capable of running 20 miles or learning a new language, with some practice you can go many hours or even 2 or 3 days without eating. If you haven’t done it before, it will take some time to develop that ability.

How long should you be fasting?

Find your Fit

There are many different ways to include intermittent fasting in your routine. Some people may skip breakfast and not eat until the evening, while others may start eating early in the day and avoid food in the late evening. You can do what works for your unique lifestyle and goals. Once you’ve found a good fit, you will find yourself less stressed about food, more productive, and more easily meeting the rest of your health goals.

Start with Snacks and Breakfast

If you're new to fasting, you may want to start by simply eliminating snacking between meals. Once you've cut snacks out of your diet, try pushing breakfast back a few hours. This will extend your nightly fast and help you stay in a fasted state without much effort but start to experience it for yourself.

As you get more comfortable with fasting, try skipping breakfast altogether. From there you can reduce your eating window incrementally so you're fasting for longer periods of time with ease. This is similar to starting running with short distances. Once you get used to it, going longer becomes less daunting and more enjoyable.

Sleeping is fasting, too

Fasting for 10 hours may sound like a big challenge, but chances are you already did that today. Don’t forget about the time you spent asleep and not eating. The reality is that literally everyone fasts every night, it is just a question of the exact timing. Sleeping means you’ll get 8 or 9 hours of fasting time for free, and adding on a few extra hours after is not very hard.

It is often quoted that breakfast is the most important meal of the day, but no one said you need to have it right upon waking up. Some people don’t eat breakfast until the afternoon or evening and are still extremely healthy.

Maybe your schedule works better with a different style of fasting. Alternate-day fasting, occasional extended fasting, or simply fasting for two days a week are a bit more complex but worth trying. Find a good starting point that works for you, then try to challenge yourself to build up from where you are. The insights in the Academy will guide you through different schedules and options so you can ramp up and try them all for yourself.

Allow Yourself Time to Adapt

Your body operates on a strong circadian rhythm that controls your daily schedule. This leads to waking and sleeping at roughly the same time, and also expecting to eat food at the same time as previously. The big secret here is that you can eat whenever you want, and your body will generally get hungry at the times when it used to eat. It will be expecting food at the same time that you had yesterday and the day before, so don’t be surprised if you find yourself getting hungry at the exact time when you usually had breakfast.

If you don’t like your current schedule, you can change it! It's important to give your body time to adapt to changes in your eating schedule. Training yourself slowly over time will let you reset your eating schedule. The good news is that after just a few days of discomfort, you’ll quickly get used to the new schedule and not feel so hungry during other times.

If your goal is a 20-hour daily fast (which can help boost autophagy) but you are only going 10 hours without eating right now, you may want to start with a simpler goal like 12 or 14-hours. Build up your tolerance slowly over a period of a few weeks, until your body gets used to the sensation and then keep going longer. For most people, an optimal fasting window will be around 16 to 20 hours, giving you 4 to 8 hours of time to focus on healthy eating.

Before the Fast

The choices you make the day before your fast will significantly affect how your body feels during fasting. As seen in the Hunger & Satiey guide, there are a variety of hormones and signals that result in feeling full or hungry. The simplest solution here is to eat a very filling and nutritious meal, so you don’t even feel hungry until your fast is over. Done right, fasting should not feel very painful.

This strategy is like filling up your car’s gas tank completely to make a long roadtrip, rather than just getting $20 of gas at every station and then running constantly near empty. Your body has the same capability to fill up completely, by eating eat the correct foods and properly satisfying your hunger hormones.

To prepare yourself for a more enjoyable fast, try the following habits for a few days before starting...

Eat Unprocessed Whole Foods

Processed foods may taste better or have longer shelf-life or be cheaper, but are not going to help you fast. If it was stored in a box for a long time or made in a factory somewhere with dozens of ingredients, then it is probably a processed food.

Less processed foods provide the many nutrients you need for the day and help you stay full for hours afterwards. When food is processed (like wheat grains becoming sugary cereal or pizza, or potatoes fried into chips) it removes satiating nutrients like fiber and protein, and destroys the delicate vitamins and minerals your body was looking for.

On the other hand, vegetables, beans, meat, eggs, nuts, whole grains, and other natural, unprocessed foods are very filling and are packed with nutrients that keep your body healthy. With the right preparation and mindset, they can taste equally good. They are not as addictive or hyper-pallatable, so you’re never going to crave them as much as a slice of pizza, but you should prioritize them the day before you plan to fast.

Control Your Blood Sugar

Eating fiber, protein, and fat will slow down the uptake of sugar into the bloodstream. If you don’t want to manually check your blood sugar with a monitor, a simple strategy for keeping your blood sugar balanced is to follow the plate method. Fill half of your plate with vegetables, a quarter of your plate with a high-quality protein source, no more than a quarter with fiber-rich whole grains, and some healthy fats for flavoring. Avoid eating carb-heavy meals like pasta, rice dishes, bread, or desserts before you start your fast, or make them a small part of the meal.

Blood sugar spikes create cravings a few hours after eating. It is like setting off a time-bomb in your body, of hunger and tiredness, even though it feels great in the moment. If you keep your blood sugar in an optimal range, you make it much easier for yourself to fast by keeping hunger and cravings at bay. Once you’ve gone a few days without a big spike, you’ll be ready to start a fast.

A few hours after eating a cookie or a pizza, you may feel very hungry. People incorrectly assume that if going just a few hours without food was so painful, fasting for 20 or 40 or 60 hours must feel infinitely worse. However, don’t let that prevent you from trying. It doesn’t have to feel like that.

The discomfort and hunger is influenced by the food quality and glucose spikes as much as the length of fast, and keeping your blood glucose levels stable for a few days will let you transition much more easily in and out of fasting. See the Glucose & Ketones chapter of the Academy for more tips and guidance on measuring your blood levels.

Eat enough food

The purpose of fasting is not to force yourself to eat less. In fact, if you are doing a long fast then you may need to eat more during your shorter eating time in order to still get all the necessary nutrients.

Tracking your food can be especially useful here to make sure you are not accidentally depriving yourself of protein or other essential nutrients. Fasting does not magically free you from your body’s nutrient requirements, and your daily average is still important to maintain.

Especially if eating just one meal a day (OMAD schedule), this will require having that meal be much larger than an average plate. If you are only eating a few hundred calories in a day or restricting yourself to just one serving and then fasting, you will not have a good time and eventually your body will generate a strong hunger signal to force you to eat enough.

Get Great Sleep

Going to bed early and catching up fully on sleep debt is essential before fasting. It is common to think that eating only affects hunger and weight, exercise controls your muscles, sleep determines your productivity, etc. but in reality they are all highly interconnected.

When you are low on sleep or misaligned with your circadian rhythm, your body increases stress and hunger hormones like ghrelin and cortisol. These chemicals increase appetite and will make it much harder to fast.

Evolutionarily this makes sense. Your body assumes a terrible emergency made you not sleep, and prepares your body to survive the upcoming attack or food shortage. The same exact eating habits on a day when you were rested and not stressed could feel much better. When you are adequately rested and get the recommended 8-9 hours of high-quality sleep (with a sleep score of at least 80 or 90), you will set yourself up for much easier fasting.

If you slept very badly or are feeling tired and getting strong food cravings, you may want to end the fast early and proactively give your body a high-protein meals to avoid stressing your body further.

Take a photo of your last meal

This starts the timer in Gyroscope and can keep you motivated until you break your fast with another food photo. Once you upload your meal, you’ll see a timer of how long it has been since your last meal that will keep you up to date on your fast.

When you’re ready to start eating again, simply take another picture and add that meal to record the end of the fast.

Things you can eat during your fast

Now you are fasting. It’s been hours since you had your last meal and the clock on Gyroscope is continuing to count up. 10 hours, 12 hours... As the time you normally eat approaches, you’re starting to think more about food and get hungry. Before pulling up UberEats and ending your fast early with a pizza, here are some simple things you can eat that won’t break the fast...

A lot of water

Just because you aren't fasting doesn't mean you should stop drinking. Constant hydration is essential. The human body can survive for many weeks without food, but only a few days without drinking water. Your body is around 60% water and needs to remain that way.

Drinking water frequently will help you maintain proper brain and organ function, so you can continue to feel your best while fasting. Staying adequately hydrated can also help prevent headaches that are often associated with fasting. For longer fasts or if you find yourself getting tired, you may also want to add salt or electrolytes.

Zero-Calorie Drinks

While water is optimal, you can also use other non-calorie beverages to help make fasting more enjoyable or productive. Sometimes when we are hungry, we are wanting mental stimulation rather than immediately needing calories. Drinking can make fasting easier, as well as help your stomach feel more full.

If you need to get work done, having drinks with caffeine can be an effective way to focus and not be distracted by food for a few hours. Black coffee, tea, herbal teas, electrolyte drinks, and other calorie-free beverages won't break your fast. Sparkling water or even sugarfree sodas can provide more entertainment than plain water, while still not breaking your fast.

If you end up at a coffee shop or restaurant, you can order an espresso or black coffee, or a tea if it is later in the day and you want less caffeine. Make sure there is no sugar or milk though. It may not be many calories, but can still end your fast.

Apple Cider Vinegar

Vinegar is very low in calories, so it won't break your fast but contains acetate, a substance that may suppress appetite and improve blood sugar regulation. You can add a tablespoon or two to your water throughout the day. Make sure you dilute the vinegar in water or use a straw to protect the enamel on your teeth.

Chewing Gum

Chewing a flavorful, sugar-free gum can help you enjoy fasting a little longer by keeping your mouth preoccupied. As an extra bonus, a mint-flavored gum will mask “fasting breath” that can be caused by ketones.

Ways to control your appetite

Certain activities performed while fasting can help you overcome hunger to make fasting a bit easier. Hunger comes and goes in waves. You can think of it like a push notification reminding you that you had a meal scheduled. You can follow it, but you can also dismiss it until later. If you're able to ride the wave, by distracting yourself or suppressing your appetite, you'll push through the hunger and realize it subsides with time.

Stay busy

The best time to fast is when you don't have time to think about it. What if you could spend 8 hours uninterrupted on something you enjoy?

Keep your mind preoccupied with work, projects, organizing, or exploring. Engaging in an activity that requires a lot of attention or makes you “lose track of time” is a great distraction. In fact, since you don't have to stop what you're doing to find and eat food, fasting can help you be extremely productive or focused.

Do Cardio

Walking, riding your bike, jogging, dancing and other simple cardio exercises can be a great way to overcome hunger and boost your mood while you're at it. Cardiovascular exercise can suppress appetite. They increase the fullness hormone leptin while decreasing the hunger hormone ghrelin, to help you forget about food for a few hours longer. Evolutionarily this makes sense — if you’re still hunting or running away from some danger, then reminding you to eat would be counterproductive.

Meditate

Practicing mindfulness can help you gain control over your appetite. Meditation, yoga, and breathwork exercises can help you shift your focus away from physical sensations like hunger. In the Gyroscope app, you can find a few fasting & food-craving meditations on the Score tab.

Enjoy the process

Fasting doesn't have to be hard. It may take some time to get used to, but it shouldn’t feel like a punishment. Many people enjoy fasting and make it a life-long habit because they love the way they feel while doing it.

Build up your fasting length over time, use the right fuel, and learn how to suppress your hunger so you can push yourself to fast a little longer!

Whether your motivtion for fasting is fat loss, longevity, or productivity, doing it the right way will make the process much easier and likely to benefit you. Now that you have the tools and training to go for a few hours or even a day without eating, you are empowered to live how you want.