Intermittent Fasting or ‘IF’ is a pattern of eating where you cycle between periods of eating and fasting. IF does not dictate what you eat, rather when you eat. It is the wilful constraint from eating for a period of time. There are many different methods with varying lengths of fasting and eating windows in the day or week. We’ll take a look at them in this post.
Intermittent fasting is actually quite easy to do, though many people feel daunted by the thought of it. Everybody fasts while they are sleeping, then eating breakfast when they wake. The word breakfast literally means ‘breaking the fast’. If you eat breakfast later in the day or skip it altogether, you are fasting. A few extra hours on top of your sleep time each day has enormous health benefits.
How Does Intermittent Fasting Work?
A ‘fast’ is anytime you are not eating. From the time you finish your food in the evening, to the time you take your first bite the next day, you are fasting!
When we are not in a ‘fasted’ state, we are in a ‘fed’ state
Intermittent fasting works because being in a fasted state means we are burning stored energy. A fed state means we are storing food for energy.
Most people nowadays spend very little time in the ‘fasted’ state because they are constantly eating throughout the day. This means their body is digesting and absorbing the food from their last meal, and either using it immediately for energy or storing it for later.
A 16:8 Fasting Day Looks Like This….
During the day we eat breakfast, a mid-morning snack, lunch, afternoon nibbles, dinner, and late-night treats. This constant state of eating and digesting leads to weight gain impairs our body from functioning properly with cell renewal and can accelerate the aging process.
Intermittent fasting allows the body to use its stored excess fat for energy
When we are in a ‘fasted’ state, we have finished digesting and absorbing the food from our last meal and now we can start using our stored energy. This gives our body a break from constantly processing food and a chance to repair itself at the cellular level.
Intermittent Fasting Benefits
The benefits of fasting are many and varied. Here are just a few.
- Body Fat Loss
- Lower/Stable Blood Sugar
- Increased Human Growth Hormone (HGH)
- Increased Fat Burning
- Insulin Sensitivity
- Less Inflammation
- Improved Digestion
- Improved Mental Clarity
- Cell Renewal (18+ hour fasting)
Which Timeframe Works Best?
Intermittent Fasting 16:8 is the most popular type of fasting and it’s the one people have the most success with. Therefore, it could be considered the time frame that works best. Because most of your fasting is done while you are asleep, you’ll get great results with an easy-to-manage plan.
The easiest timeframe to start with is the 12-hour fasting window because you are asleep for a large portion of that time. However, everyone is different so it is worthwhile trying a few to see what works for you. Start by pushing your breakfast back an hour each day until you reach your desired fasting window.
Here are some of the most popular intermittent fasting times.
This is a great starting point for beginners who are completely new to this way of life. Example: Dinner at 7pm, breakfast at 7am the next day. Most people are already doing this, or close to it. But late-night dinners and evening snacking will trip you up. To begin tapping into the fat-burning zone, the 12-hour fast is a great place to start. Take note of when you currently eat and slowly increase the fasting gap between meals, you’ll get to 12 hours in no time.
This plan is often used by women; it is argued by some people they don’t need to fast as long as men. It’s a gentle step up from 12:12 and may work for you. Use your intuition. Eg. Dinner at 7pm, breakfast at 9am.
Eat within a period of 8 hours and fast for 16 hours. This is a daily or almost daily fast. Eg. Start your fast after dinner, and don’t eat again until lunchtime the next day, skipping breakfast. If you have dinner at 7pm, you would break your fast at 11am the next day.
Many people have dramatic weight-loss results by increasing their fasting window to 18 hours and eating within a 6-hour window. Eg. Dinner at 7pm, lunch at 1pm
Eat within a 4-hour window followed by a 20-hour fast. Eg. Start your fast after dinner and wait 20 hours until you eat again. If you have dinner at 6pm, your next meal would be at 2pm. Eat one large meal a day or two smaller ones in your 4-hour eating window.
Known as one meal a day or OMAD, this fast is once or twice a week, not daily. Eg. Fast from lunch on day one until lunch on day two. You still eat each day, but only once.
Fast for an entire day and night, about 36 hours altogether. Eg. Fast after dinner on day one, eat nothing on day 2, and break your fast on the morning of day 3.
This is a 3 day fast, and should not be considered lightly. Extended fasting should not be undertaken without checking with your doctor before you start.
Eat normally 5 days a week, but on 2 days, consume about 500 calories for women, 600 for men. Fast days can be back-to-back or split. This method came into the mainstream via Michael Mosley’s book The Fast Diet
It’s very important to make sure you are getting all your nutritional requirements within your eating window, no matter which plan you choose. Always make sure you are getting enough calories when you break your fast for what your body needs.
It may also be helpful to not subscribe to time specifics. If you want to keep it simple, eat dinner then break the fast at midday/lunchtime the next day.
Intermittent Fasting Mistakes
- Jumping in too fast – start with 12:12 and work your way up
- Not drinking enough water
- Eating too much during your eating window
- Eating too little during your eating window
- Giving up too soon (within 3-4 weeks)
- Choosing the wrong plan for your lifestyle
- Not fasting clean – eating whole foods, not processed ones
Do’s & Don’ts for Intermittent Fasting
- pick a fast you will succeed at
- eat nutritious foods in your eating window
- eat dinner early and fast in the evening
- include your period of sleep in your fasting window
- stop eating two hours before bed
- stay hydrated
- start with 24 hours + fast or multi-day fast if you have never fasted before
- start without consulting a health professional
- give up too soon, it gets easier, the longer you do it
What Can I Have When I am Fasting?
While fasting, you do not consume any food or drinks that contain calories. This is to prevent a spike in your blood sugar and insulin levels, decreasing your fat-burning potential.
See ‘Drinks that do not break a fast’ below for more information.
Foods to Avoid in Your Eating Window
There are many foods to avoid during your eating window, primarily, high carb foods, processed foods and industrial seed oils. Feed your body the right fuel – whole unprocessed food as close to its natural state as possible.
Here are a few examples of what to avoid:
Bread, cereals, pasta, baked goods such as donuts, bagels, and pastries.
Cakes, cookies, biscuits, sweets, candy
Soft drinks/sodas, sports drinks, fruit juice
Vegetable oils including canola, vegetable, corn, soy, palm, safflower, etc
Fried foods and fast food such as pizza
Commercially processed meats
How to Begin with Intermittent Fasting
Start with a 12 hour fast. Eat dinner at 7pm and breakfast at 7am the next day.
Work up to a 16:8 fast with this suggested timeframe;
6.30pm – Dinner
7.30pm – Start your fast. Enjoy water or herbal tea until bedtime.
8am – Start your morning with water and black coffee or herbal tea.
11.30am – Break your fast with a late breakfast or early lunch.
3pm – Make sure you’ve kept your water levels up. If you need a snack, try a small handful of nuts.
6.30pm – Dinner (and repeat)
The Nutrition Geek has a few more tips for fasting in his post When Weight Loss Stalls.
Drinks That Do Not Break a Fast?
For daily intermittent fasting when your goal is weight loss, lowering blood sugar, and/or improving insulin sensitivity, the following drinks will not break your fast:
- Black coffee (with a dash of heavy cream),
- Unsweetened tea
- Lemon water
- Apple cider vinegar
If your goal is maximum autophagy (see below) then anything beyond water and electrolytes will break your fast.
Bulletproof coffee with butter/coconut oil + MCT oil might be ok as they do not stimulate blood sugar or insulin. Bulletproof coffee is meant to help you push your first true meal until later. If it is not doing that, it might not be worth drinking one.
Anything with carbs or protein such as bone broth or collagen powder will technically break your fast as it will cause a spike in insulin.
Some people will consume collagen powder and bone broth during their fasting window, but you might be better off without them if you want to improve your insulin resistance.
If you are fasting for 72 hours – Bone broth, tea, black coffee, water, electrolytes are ok but not sweeteners.
What is Autophagy?
When we fast, the first change that happens is we switch to ketosis, where our body burns fat as fuel. But if we keep fasting for 18 hours and beyond, the body switches from keto into autophagy.
Autophagy is the body’s way of cleaning out damaged cells, in order to regenerate newer, healthier cells. When you haven’t had a meal, your body starts looking for more fuel from within and will clean out damaged cells, toxins and fat.
It is recycling and cleaning at the same time. Think of it as ‘taking out the garbage’ or hitting a reset button on your body.
Fasting is one of the most effective ways of stimulating this healing autophagy process. Autophagy begins after 18-20 hours of fasting.
Benefits of Autophagy
- Cellular Repair and Creation
- Improved Immune Function
- Improved Cognitive Function
What to Do When You Feel Hungry
Drink black coffee, tea and water. Your body will adjust and get used to your fasting.
Keep yourself busy or distracted with work.
Some people find it useful to clean their teeth as the toothpaste taste puts them off wanting to eat food.
How to Break a Fast
Breaking a short fast (anything less than 36 hours) can be done by simply eating a low-carb, high-fat meal. Choose whole foods to break your fast, rather than processed foods. You don’t want to undo all the good work your body has just done.
If you have done a long-term fast (over 36 hours), it’s important to break it gently with a small meal. Eating a large meal may make you feel sick. Give your body time to adjust to food.
It’s also extremely beneficial to break a longer fast with probiotics, prebiotics and polyphenol foods. Some examples are fermented foods such as sauerkraut and kefir, chia seeds, some nuts, spices, berries and dark chocolate (85%+). You can check out a full list here.
How to Train your Body to Fast Longer
Extend your fasting window 1 day a week. If you’ve been doing 12:12 hours, try pushing to 16:8 hours, then eventually work up to your desired fasting period.
Drink something that might calm your hunger cravings like water, electrolytes or bone broth. However, note that since bone broth contains protein, it may take you out of autophagy if that is your goal.
Try the 2-2-2 Hack: Eat 2 tbsp MCT or coconut oil, 2 tbsp grass-fed ghee and 2 tsp of unrefined, organic salt that retains all its natural trace minerals. You can do this twice a day to stabilise blood sugar and curb hunger.
Shouldn’t We Eat More Frequently if We Want to Lose Weight?
The answer is NO. This concept doesn’t make intuitive sense and it doesn’t make logical sense either.
Every time we eat, the body releases insulin. Insulin is the ‘fat storage hormone’ and when insulin is high, we cannot burn fat. When we are insulin resistant, it becomes very hard to burn fat (and lose weight) because insulin is always high.
Carbs have the greatest insulin response but protein does have a moderate response as well. Protein is good for you, but if you eat more than you need, it will also get stored as fat. Eating high insulin response foods plus constant eating throughout the day will lead to insulin resistance.
Signs You Should Break Your Fast
Fasting, especially extended fasting, can be very beneficial for some people but it’s important to listen to your body and know when something is wrong.
Although we fast for weight loss or to improve our health, it’s important to put our overall health first! This includes checking your blood sugar regularly if you are a diabetic as well as ensuring that you’re getting enough water and electrolytes.
Here are some of the signs to look out for during your fast which indicate that it’s time to stop.
- Persistent nausea, vomiting or diarrhoea
- High or low blood sugar
- True hunger (felt in the mouth)
- Dizziness, fainting or extreme weakness
- Rapid, slow or irregular heartbeat
- Any instinct that something is wrong
If you experience these signs, break your fast and re-feed safely and re-visit your doctor.
Should you Exercise When Fasting?
If you are doing a longer fast, over many days, you should not exercise. Let your body use its ingrained intelligence to do its job properly.
If you are fasting less than 24 hours, yes absolutely you can do exercise. It’s an effective way to burn fat, gain more energy and heal your body.
Who Shouldn’t Fast?
There are 6 categories of people who should not fast;
- People who have fasted too much and it’s time for some variation
- Women, one week before their cycle begins
- Pregnant women
- Nursing mothers should not fast longer than 15 hours
- People who have an eating disorder
- People who are sufering extreme adrenal fatigue
Fasting is a natural healing system for your body. It has the power to heal itself from many ailments if given the right environment – fasting, sleep, yoga, meditation and the right fuel – nutrition.
For more information on recent studies – https://www.nature.com/articles/s43587-020-00013-3
For further reading, check out Jason Fung’s book The Complete Guide to Fasting
If you want to dive deeper into Intermittent Fasting, Dr. Mindy Pelz has an excellent informative YouTube channel. https://www.youtube.com/channel/UC4cNjUPc2gQKucX3hLUayYQ
Disclaimer – This guide is written for adults. Please see your health doctor, nutritionist or dietician before changing your diet. If you are on medication of any description, please see your doctor before embarking on any fast. Do not fast if you are pregnant, struggling with an eating disorder, underweight, or under the age of 18 years.