A Comprehensive Guide To Fasting : Timeline, Stages & Benefits (2023)

Common Concerns About Fasting

Most people have some concerns when it comes to implementing fasting into their lifestyle. This is totally normal, and so I want to spend some time here addressing the most common concerns.

The first, of course, is about hunger.

Managing Hunger During A Fast

Remember that hunger is a hormonal signal — a data point. More often than not, hunger is a state of mind more than the state of your stomach.

Eating in response to hunger is a learned response, and while it takes a while to change that habit, you are not obliged to eat just because your body sends a signal.

As your body becomes more accustomed to fasting, it will become more fat-adapted, meaning that instead of just burning glucose for energy, you start to burn fat instead.

This process takes some time, so to help manage your hunger, your last meal or two before going into your fast should ideally be lower carb, as this will help the transition to burning fat instead of glucose go more smoothly.

It’s important to stay ahead of thirst — stay hydrated, and if you’re having a lot of activity in your digestive system (like growling or pangs), carbonated water is really effective for settling that down. Coffee — regular or decaf — has also been shown in research to suppress hunger for some people.

Another option is adding salt to your water.

This is a magical tool — if you’re feeling really low-energy, a little shaky, or you’re not sure you can continue, as soon as that feeling starts, you need more salt.

Studies of prolonged fasts have found no evidence of electrolyte imbalances in the blood, however, salt is still a great tool to reduce hunger.

You can add a teaspoon of sea salt to some water, you can chew on some coarsely ground salt to bring yourself back to equilibrium. I also really like the LMNT hydration packets.

There are about 1.7 grams of sodium in a teaspoon of pink Himalayan sea salt. Two to three grams of sodium daily is a good starting point around day 2 of any fast due to the increased loss of sodium that happens through the urine while fasting.

*If you have a health reason for avoiding salt or if you are on blood pressure medications make sure to talk to your doctor before undergoing any fasting protocol.

Don’t forget that exercise is a really powerful appetite suppressant.

People often assume they shouldn’t exercise during a fast, and while I don’t recommend very high-intensity workouts, exercise directs blood away from the digestive system and into the muscles, which helps to quiet that hunger signal.

If you’re having symptoms of irregular blood sugar levels, some green tea with cinnamon is a useful aid as cinnamon can help regulate blood sugar.

And if you’re struggling with that inner voice that’s telling you this is too hard, you should stop, it’s too much, then a meditation or mindfulness practice can be extremely useful in quieting that voice so you can carry on (assuming you’re not actually experiencing any extreme symptoms that would indicate that you should change what you’re doing).

My favorite tools for meditation and mindfulness are Headspace, Calm, the Muse brain-sensing headband, and 10% Happier.

Sleep Quality

Regular fasting can help to improve your sleep quality over time.

It is very important to prioritize sleep while you are fastingbecause when you don’t get good sleep, your body releases a different set of hormones that will make you feel more hungry than usual.

You want to shoot for 7 to 9 hours of solid sleep that is deeply restful and uninterrupted so that you’re not risking worse hunger than is necessary.

If you need a fantastic tool to help track your sleep and the changes to your health during your fast, read about my favorite health tracking device.

However, it is common to experience some sleep disruption when you are new to fasting. Read below for my favorite form and dosage of magnesium to help with sleep.

Energy and Brain Function

Most people report that when they’re fasting, their mental clarity and energy levels are actually better than usual.

Keep an eye on your energy and brain function as you experiment with different types of fasting — are you high-energy in the morning and then seeing a dip in the afternoon? Then schedule all your important tasks for the morning and give yourself less demanding stuff when you’re in that dip.

Observe how your particular body responds to your fasting protocol, and schedule your days accordingly.

Discomfort and Symptoms

It’s fairly common for people to report dizziness and/or headaches when fasting. This is brought on by dehydration and a lack of salt. Most of the discomfort with fasting can be avoided if you are well hydrated and taking regular salt.

If you’re getting constipated or your bowels are slowing, which is common on multi-day fasts, make sure you’re eating enough fibrous fruits and vegetables during your non-fasting days, and supplement with magnesium. Magnesium helps with relaxation, muscle cramps, constipation, sleep quality.

I recommend taking 400-600 mg of magnesium citrate daily to keep your bowels regular or magnesium glycinate if you are having difficulty with sleep or headaches. Click the image below to create an account with Fullscript to gain access to the highest quality professional-grade supplement brands.

If you get heartburn after your fasting period, make sure that you’re eating slowly, chewing your food thoroughly, avoid large meals and avoid overeating.

Make sure you stay upright for a while after meals — don’t go to bed or lay down immediately after eating.

The more you fast, the more you’ll develop a sense of what’s worth pushing through.

You’ll get more familiar and comfortable with the signals your body is sending, and so you’ll be more able to identify when to persevere and when it’s time to take a step back, try something different or try again later.

Exercise and Movement

Keep exercising and incorporating movement into your daily routine during your fast.

If you experience unusual discomfort during exercise, it’s usually a sign to dial it back a little bit — it doesn’t need to be as high intensity as you might usually go for.

Make sure you’re hydrated and have enough salt, especially if you’re sweating during the workout.

Blood Sugar and Blood Pressure Management

If you’re on blood sugar medication or struggle with blood sugar issues, make sure you work with your doctor and test your blood sugar regularly throughout your fast. Your medication dosages may need to change during your fast. Your blood pressure can go down when you’re fasting, so you want to track both components to make sure they’re staying within a safe range during your fast.

Fasting Myths

If you fast, or intend to, there are a few myths that you’re going to run into. I hear these 5 myths all the time, and it’s important to go into this lifestyle change with the knowledge of what’s true and what’s not.

Fasting Myth #1: Fasting puts you into starvation mode and decreases your metabolism.

Metabolism is measured by BMR — your basal metabolic rate. This measures the amount of energy your body burns to keep all your organs functioning optimally.

When your BMR goes up, your metabolism goes up. This supports healthy weight maintenance and weight loss when necessary. When your BMR goes down, your metabolism goes down, and this can lead to difficulties with weight loss or a weight loss plateau.

Your BMR goes up naturally when you’re cold — your body has to shiver to maintain heat — and your BMR goes down naturally when you reduce your daily intake of calories. This doesn’t happen after one meal; it happens when you’re running at a caloric deficit for a long period of time.

This is why in some cases, you may have heard from a doctor, nutritionist or health coach that in order to lose weight, you actually need to eat more.

It’s counterintuitive, but it’s true.

When you experience reduced metabolism, you feel cold, tired, hungry, and have low energy. If you are already experiencing those things, you may need to first spend some time repairing your metabolism and getting your food intake back on track before jumping into fasting.

Fasting Myth 2: Fasting makes you lose muscle mass.

This is the first concern I hear from clients who want to build or maintain their lean muscle mass.

They’re worried when I suggest adding fasting to their routine, because they’ve heard so many times that when you’re fasting, your body breaks down muscle to use for energy.

In just about all cases, this is not going to happen. The hierarchy of how your body converts fuel to energy is that first you burn glucose, then you burn fat stores, then you burn muscle.

Your body will not start breaking down muscle tissue until your fat stores account for less than 4% of your total weight.

To put that into context, elite male marathon runners — who are extremely lean — have a body fat percentage of around 8%.

So for most of us, we’re never going to get to a place where our body is going to start breaking down muscle tissue for energy.

When you’re fasting, your body actually conserves muscle. Fasting triggers the release of growth hormone, which helps you to build your lean muscle mass.

During the fast, your muscles might feel a little deflated or look a little smaller, but this is due to water loss, and it will come back once you get more hydrated.

If you’re trying to continue building muscle while fasting, you have to exercise. There’s no other way to do it.

Regardless, exercise and daily movement are paramount: things like weight training, bodyweight training, yoga, walking, biking — all these things will help your body build and maintain muscle mass when you’re fasting.

Fasting Myth #3: Fasting causes low blood sugar.

While you might experience some symptoms of low blood sugar — like shakiness or feeling ‘hangry’ — those usually only happen when you first start incorporating fasting into your lifestyle.

If you are prone to hypoglycemia or if your diet is very high in sugar or starch going into the fast, that can cause some blood sugar issues.

But once you become fat-adapted — when your diet is a good fit before your fast and you start to burn fat for energy easily — your body will have all the nutrients it needs to keep a steady balance while burning fat and running on ketone bodies.

Fasting Myth #4: Fasting results in overeating.

This is something that many people are afraid of, and studies do show that when you first start fasting, there is an increased risk of overeating, particularly if you’ve ever had any kind of disordered eating in the past.

Fasting can trigger your old habits so if that’s your situation, it is important that you’re working with a therapist to make sure that this change doesn’t lead you down a bad path. For many people with a history of eating disorders, fasting is not going to be a good fit.

However, if you have not experienced disordered eating in the past, it’s normal that your hunger hormones won’t have fully regulated in the early stages of a fast.

This can make you want to scarf down everything in sight after your fasting window ends.

I’ve been there before too, but I would argue that it’s usually a sign you’re not ready for that length of fast or that you need to go into the next one with your diet a little more dialed in.

Fasting over the long run actually helps to reset the hunger hormones — the leptin and ghrelin that we talked about earlier — and your appetite becomes more stable over time.

Fasting Myth #5: Fasting leads to nutrient deficiencies

Actually, the opposite tends to happen.

Your body reduces the excretion of vitamins, minerals and the by-products of broken-down fat and protein during a fast. And because you have less bowel movements (particularly with those longer multi-day fasts), you’re losing less through your stool as well.

Electrolytes, magnesium, potassium, calcium, phosphorus and so on all remain stable during longer-term fasts.

The only time that micronutrients — vitamins and minerals — become a major problem is when you’re chronically deficient in those nutrients already and you’re doing a longer multi-day fast.

In that case, you may want to take a multivitamin, and for this I recommend a supplement calledPrimal Multi by Designs for Health. Click here to create an account with Fullscript to gain access to this pharmaceutical-grade supplement. If you are located outside of the US, Thorne’s Basic Nutrients 2/Day is my favorite.

Tips To Get Through A Fast

In this section I want to share 10 of the tips and strategies that have proven really effective for helping you get through a fast, whether that’s intermittent fasting or a multi-day fast.

1. Drink water.

I really can’t emphasize this enough. The minute you start getting even a little bit dehydrated is when you’re going to notice hunger symptoms and discomfort kicking in.

Start each morning with a big glass of water and keep a water bottle with you at all times through the day. Put sticky notes up around your house, set a reminder on your phone — do whatever you can to remind yourself to keep hydrating.

2. Stay busy, and change your daily routine slightly.

Our daily routines are really linked to hunger signals, so it’s a good idea to change things up, especially early in your fasting practice.

Give yourself a reward each day by doing something you might not otherwise do, to change up the rhythm of the day.

That might be going for a walk, getting a massage, taking a nap or meeting up with a friend — anything that you really enjoy doing and that feels like a reward should be fit into each day.

3. If you’re already a coffee drinker, keep drinking black, unsweetened coffee throughout your fast.

I wouldn’t start drinking coffee if you don’t already, but if you do, it’s a really effective appetite suppressant.

The only reason you would stop if you are a coffee drinker is if your goal is complete digestive rest, but if your goal is weight loss or longevity, coffee is fine.

4. Ride the wave of hunger.

Remember that hunger doesn’t last forever — it will hit you, and then, like a wave, it will recede. When it does hit, you want to drink water, sparkling water, tea, or coffee.

Change your environment — go for a walk or do something to get your mind occupied with something else until that moment of hunger passes.

5. Don’t tell everyone you meet that you’re fasting.

Be selective with who you talk to, because not everyone is familiar with the benefits of fasting or why you would want to fast, and their lack of support or negative reactions can feel very discouraging.

Only involve people in the process who understand what you’re doing and are going to be supportive.

6. Give yourself a month to get used to fasting.

Fasting is like any other life skill — it takes practice. If you’re new to this, give yourself some time to figure out what type of fasting your body really benefits from, how your body responds during a fast.

Experiment a lot and give your body time to get used to different types of fasting.

7. Work on improving your diet during your non-fasting period.

Remember that fasting is not an excuse to just eat whatever you want afterwards — you still want to practice healthy eating and keep improving your diet over time.

When you change your diet and you start fasting, that’s when truly amazing things can happen in your health.

8. Have a protocol in place for when you break your fast.

We’ll talk about this more below, but it’s important that when you break your fast, you don’t just go on a binge and eat everything in sight.

Carefully plan your first meal, and then work out how you can return to eating normally without a big blow-out after the fast. My favorite way to break a fast is with some broth or chicken soup.

9. Fit fasting into your life.

Try not to change your life to fit a fasting schedule — instead, you want to change your fasting schedule to fit your life.

It’s much more sustainable doing it this way, because your fasting practice is not coming into conflict with your other commitments and priorities.

Determine if you have any non-negotiables in your life. It could be work schedules, family commitments, travel plans, and things that happen on a daily basis, and then experiment until you find a style of fasting that works with those commitments.

10. Start slow, and adapt your fasting strategy often.

As I’ve said, the first month of fasting is really one big experiment to figure out what works for you. But you want to keep experimenting and tweaking even beyond that time to keep observing what’s working for your body.

Your body will change over time, and so your fasting practice should too.

When To Change or Stop Your Fast Early

Fasting is always going to create some physical discomfort. It’s totally normal to experience hunger (often far more intense than you’re used to), as well as plenty of other symptoms.

Many people report headaches, dizziness, achy joints, nausea, brain fog and disruptions to body temperature when fasting.

To an extent, all this is normal, and usually the discomfort will pass in a short period of time.

Fasting is like being in a shallow pool: if you get worried, you can just put your feet down (and eat!). Everything will be fine as long as you don’t panic.

However, sometimes your body may not respond well to a particular fast. This can be the result of eating too many starches and carbs right before starting the fast, or it can be a consequence of increased stress or some other issue going on with your health.

So if you are experiencing sustained, persistent symptoms, then it might be time to reassess this particular fast. Vomiting or ongoing nausea, fatigue, or brain fog are clear signs that you should take a step back and try something different.

If you are doing a multi-day fast — longer than 24 hours — you should always do so with some medical supervision or support. Inform one or two trusted people in your life (such as your partner or close friend) about your fast so that they can support you and help you make the decisions that will be right for you.

How To Break A Fast

The most important thing to keep in mind when breaking your fast is to do it gently. The longer you’ve been fasting, the slower you need to take this.

There is a natural tendency after fasting to dive right back into food and to overeat, and that can lead to a lot of stomach discomfort and create a lot of discomfort.

Don’t just dive into a pizza, especially after a longer fast, because it’s going to be quite painful!

If you’ve been fasting for 24+ hours, you want to start with a small snack, wait 30 minutes, then take an assessment of how you feel to see if you’re still hungry.

Make sure to eat slowly, chew your food really thoroughly. Try something light, like some avocado, a small piece of fish or some vegetables cooked in olive oil.

I would avoid raw food in general, as that can be harder to digest. If you have trouble with eggs or another type of food (or you’re not sure how they affect you), I recommend waiting a couple of days until your digestive system has warmed back up.

And of course, avoid any high-sugar food, highly-processed food, and any foods you know you have an intolerance to.

If you’re really craving sweets, try some fruit: berries or an apple can be a great option.

I almost always break my own fast with a broth or soup. I have a chicken soup recipe that is my cure-all for everything — I use it to reset my hunger, to calm my digestion, to get through a cold or flu, reduce bloating or get back on track after a period of overindulgence — and you can find that recipe here.

If you’ve been doing a multi-day fast, it will usually take about half the number of days you fasted for your digestive system to return to normal.

Don’t forget to keep drinking plenty of water once your fast is done, as that will continue to help your health in all areas.

* * *

Fasting is a lot like exercise. At the beginning, you’re going to feel a bit sore. But the more you do it and the fitter you get, the easier and more routine it becomes.

The more experience you have, the more you’re going to feel like fasting is a much-needed break from food.

Of course, food is one of the greatest joys life has to offer and it should be.

Food is culture, it’s family, it’s celebration — and fasting allows you to participate in all of those parts of life without anxiety and food guilt.

It allows you to live your life fully, without losing the progress you’re working so hard to achieve.

It empowers you to heal your body in a sustainable way, and to take your future health into your own hands.

Fasting is an incredible tool that can have a truly transformative impact on your health.

I encourage you to start experimenting so you can enjoy the myriad of benefits it can create. And if you want help creating the most effective and safest protocol for you and your health, click here to work with me.


What are the 5 stages of fasting? ›

Intermittent fasting can be divided into 5 stages, from feeding to post absorptive to gluconeogenesis to ketosis to protein conservation. Each stage is accompanied by different physiologic processes, so understanding the stages allows you to target the benefits of intermittent fasting.

What are the timeline of fasting? ›

The four stages of fasting.

Stage 1: Fed state (0-3 hours) Stage 2: Early fasting state (3-18 hours) Stage 3: Fasting state (18-48 hours) Stage 4: Long-term fasting state (48+ hours)

What is the best timeline for intermittent fasting? ›

The 16/8 Intermittent Fasting Schedule

Of course, as with any intermittent fasting diet, you have complete flexibility in terms of how you schedule your 16-hour fast and 8-hour eating window, but something around the 10 AM to 6 PM, 11 AM to 7 PM or noon to 8 PM range is typically what people use for the eating window.

What is the 4 4 12 fasting rule? ›

The 4-4-12 method has a shorter fasting window—12 hours—but eliminates snacking between meals. The goal here is to fast for at least four hours between breakfast and lunch, four hours between lunch and dinner, and at least 12 hours between dinner and breakfast the next day.

What is the hardest stage of fasting? ›

No matter how many times I fast, day one is never easy and day two is always the most difficult (ghrelin, the hunger hormone, is said to peak on day 2 of a fast). On days three through six, I experienced some of the best energy, mental clarity/focus and mood stability that I've ever felt in my entire life.

Does lemon water break a fast? ›

Long story short - the answer to the question “Does lemon water break a fast?” is no, lemon water does not break a fast. Lemon water contains almost no calories and zero sugars, it doesn't raise insulin levels, which means it will not break your fast (1).

Why is 16 hours the magic number for fasting? ›

Both 12-hour fasting and 16-hour fasting can be effective for weight loss, but 16-hour fasting may be more effective because it may lead to a greater reduction in overall caloric intake (through a more condensed eating window) and promote more significant reliance on fat burning.

Does coffee break your fast? ›

The short answer is yes, you can drink coffee while intermittent fasting. However, this answer comes with a big caveat: You can only drink black coffee while intermittent fasting. Coffee drinks with cream, sugar, or other forms of calories will break your fast.

What should I drink while fasting? ›

Beverages that you can drink while intermittent fasting includes water, mineral water, seltzer, tea, coffee, apple cider vinegar, and flavored water. Drinks that you should avoid while fasting include alcohol, diet sodas, coconut water, and milk.

Does fasting burn belly fat? ›

Nutrition experts say that switching back and forth between fasting and eating again can bring many health benefits, including weight loss, reducing belly fat. However, to lose belly fat and get the nutrients you need, you should eat healthy, limiting sugary desserts and processed foods.

What is the rule of fasting? ›

The golden rule in fasting is that it is a fast—this means no calories, no nutrients, no food. Even breaking the fast slightly with some food can throw severely limit the benefits you'd otherwise experience. It's important to stay consistent with a feeding and fasting window and stick to that window as best as you can.

What is the best intermittent fasting time to lose belly fat? ›

Best Intermittent Fasting Method For Subcutaneous Belly Fat

16/8 Method: Fast for 16 hours and have an 8-hour eating window daily. For example, you might fast from 8:00 pm to 12:00 pm the next day and eat between 12:00 pm and 8:00 pm.

How many days does intermittent fasting take to show results? ›

That's how long it takes your body to switch from using glucose for energy to using fat for energy. Additionally, it will take your body a while to get used to this new eating schedule. So don't expect results right away. You may need to wait between 2 and 4 weeks to see or feel any results.

What is the best fasting schedule for weight loss? ›

The 16/8 intermittent fasting plan is one of the most popular styles of fasting for weight loss. The plan restricts food consumption and calorie-containing beverages to a set window of 8 hours per day. It requires abstaining from food for the remaining 16 hours of the day.

How do I know when my body is in fat burning mode? ›

You'll see changes in your body composition. Losing pounds or losing inches is the primary sign you're burning fat. It leads to a slimmer appearance and more muscle definition. Your exercise stamina increases, and you are getting fitter.

What is the most effective fasting pattern? ›

A person needs to decide on and adhere to a 12-hour fasting window every day. According to some researchers, fasting for 10–16 hours can cause the body to turn its fat stores into energy, which releases ketones into the bloodstream. This should encourage weight loss.

How do I know I'm in autophagy? ›

A key sign of autophagy is reduced appetite. It's likely due to changed levels of hormones like glucagon and insulin.

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