When you stop and consider for a moment that around two-thirds of people walking around in countries like the UK and US are overweight, it seems undeniable that we haven’t properly understood how the human metabolism works.
Our metabolism is the engine of the body, our fuel system. It’s of fundamental importance to how our body operates from moment to moment.
So perhaps it’s not surprising that when it goes wrong and we become overweight, this opens the door to other major health problems such as high blood pressure, heart attacks, stroke, type 2 diabetes, dementia and cancer.
What this suggests is that we need to reevaluate ALL diet orthodoxy, because the old advice of eating low fat and counting calories hasn’t worked.
One classic piece of diet orthodoxy is that we need to eat 3 square meals a day or our blood sugar will plummet, we’ll get irritable and unable to focus, we’ll enter ‘starvation mode’ and our body will begin breaking itself down.
But what if this is completely wrong? What if this just another piece of bad advice that keeps us fat and sick?
What if in fact we evolved to cope just fine in periods without food and that in fact it was GOOD for our metabolism? What if eating relentlessly to a regimented schedule was actually BAD for us?
If so, fasting could be as important to our self-care as exercise! That’s a pretty radical idea and I’m not claiming it’s proven by the science but I’m just throwing it out there for debate.
What the scientific studies suggest is that all the systems of our body benefit from fasting: for example our metabolism, hormones, immune system, brain, gut and heart all see benefits. This isn’t just about losing weight!
This article isn’t going to be a deep dive into the science on fasting. Instead, I’m going to run through the key points to give you an overview.
Then you can decide whether you want to give it a try yourself. If you’ve already tried it and liked it, I’d encourage you to go deeper by fasting for longer!
What is Fasting?
- Fasting means that we’re deliberately abstaining from some or all food for a period of our choosing. In this respect it’s completely different to starvation, which is where there is just no food available.
- In a way fasting is a ‘pretend starvation’ that mimics the times without food that our ancestors coped with and evolved with.
What Happens In My Body When I Fast?
- Human biochemistry is extremely complex however we know that the body first uses its reserves of glucose, which last for 12-24 hours.
- Then the body switches from burning glucose to burning fat.
- Blood sugar goes down and blood levels of ‘ketones’ go up.
- Ketones are the body’s alternative fuel source and, in simple terms, are based on fat rather than sugar.
- This enables us to ‘unlock’ the huge amount of calories stored in fat cells around the body. These stores are MUCH larger than the body’s reserves of glucose, even on a lean person. These fat stores are normally locked away because when we eat regularly it tends to increase levels of insulin in our blood, which in turn sends signals to our body to store fat, rather than burn it.
- The body can make it’s own glucose for some functions that absolutely require glucose, in a process called ‘gluconeogenesis’.
Why is Fasting Good For Me?
- Fasting is a ‘stressor’ that our body responds positively to, like exercise.
- It gives the body a chance to go into repair mode, as it no longer needs to expend energy on breaking down the last meal we ate.
- The body clears away unneeded cells in a process called ‘autophagy’.
- This brings down inflammation, something that’s a big issue for many of us. Check out Inflammation: Putting Out The Fire
How Do I Fast?
- During the fast drink plenty of fluids such as water, tea or coffee. Being dehydrated makes the fast more difficult and has no additional health benefit.
- Drink fluids without sugar or artificial sweeteners.
- Bone broth is good to drink during a fast as it replaces electrolytes and provides nutrients with virtually no calories.
- Juices have calories so break the fast slightly, but do provide cleansing benefits if freshly prepared, due to their high nutrient payload. Check out our Gut-Calming Green Juice recipe.
Will I Need A Duvet Day?
- No! Your metabolism speeds up and energy levels increase. This may be evolution’s way of kicking us up the butt to go hunting for food! Can you imagine how quickly humans would die out if we felt sleepy BEFORE eating instead of AFTER?
- Mental clarity increases.
- Fasting may be particularly good for our brain, where reducing inflammation is especially important. Take a look at Leaky Brain: Astonishing New Discovery and Brain Health Begins In The Gut
Will I Lose Muscle?
- Keep exercising as normal, don’t decrease your training intensity. Your body will gradually get used to burning your fat reserves for fuel
- Muscle is preserved by the body during a fast
- Again this makes sense from an evolutionary perspective: we need our full strength and agility to go hunting and gathering!
Will I Go Crazy From Hunger?
- Hunger doesn’t keep rising but comes and goes in waves, particularly decreasing after the 2nd day.
- Drinking bone broth can particularly help to calm hunger when it’s peaking.
When Should I Start And Stop?
- Start when you feel like it, stop when you feel like it, there are no rules.
- Listen to your body: eat something if you feel BAD as opposed to hungry.
- Benefits kick in from about 12 hours onwards. Most people can manage 24 – 72 hours with no problem.
- Some experts advise a 1-week fast once a year to help protect against cancer.
- Consult your doctor if you have any doubts. Some medication dosages may be different during a fast.
How Should I Break A Fast?
- Gently! Don’t gorge yourself immediately but start with something small or you may feel uncomfortable, depending on the length of time you’ve been fasting for.
- People tend NOT to binge-eat after a fast but instead just naturally eat normally.
- Some people report that they feel less inclined to eat processed junk food after incorporating fasting into their lives.
- For more ideas on what to eat check out Clean Eating: More Than Just A Fad
How Often Should I Fast?
- Incorporate fasting into your lifestyle. It needs to be done regularly to keep up the benefits.
- When done for short periods (up to 24 hours) every week, this is known as Intermittent Fasting
- A popular example of this is the 16:8 Diet where you eat all you food each day in an 8-hour window and fast for the remaining 16 hours.
Will a Calorie-Cutting Diet Give Me The Same Benefits?
- Calorie restriction also has benefits in terms of allowing the body to heal and repair. However it is less effective than fasting and slows our metabolism instead of speeding it up. It is not strictly ‘fasting’.
- An example of this is the popular 5:2 Diet, which involves eating whatever you want for 5 days of the week then eating only 25% of your normal calories on the other two days.
The Idea of Not Eating Just Freaks Me Out!
- I get it! I was the same to begin with. After all, eating is about as fundamental as breathing and we never take a break from breathing (unless you’re a free diver!)!
- However we often fast for 12 hours overnight without even thinking about it. Try 16 hours first, then gradually increase. My longest so far is 60 hours and I felt great during and afterwards.
What Will My Doctor Say?
- Many doctors will laugh at the idea that something as simple as fasting could provide benefit, but then again, the science is pretty new. They may be impressed when they see your health markers improving across the board.
- The difference between taking meds and improving your health through fasting is that only the latter involves the body using its own healing power, which has zero side-effects.
Who Should Not Fast?
- Pregnant and breastfeeding women should not fast
- It’s generally believed that children and adolescents should not fast. However some experts argue that it would potentially be beneficial if the child/adolescent is overweight.
- If you’ve tried fasting and you felt terrible, don’t push it. It’s not for everyone.
Nutshell It For Me!
- Fasting brings down inflammation and makes every system in our body function better, including our gut.
- Some people believe that fasting is so powerful it can potentially put your doctor out of business! The science is still developing but there’s also a huge amount of anecdotal evidence of the benefits.
- In some cases fasting is more potent than medication and without a single side-effect, except that you’ll also lose weight!
- I asked our Gut Geek followers on social media about their experience with fasting and the vast majority had good reports. A small number, perhaps 5-10% said it just didn’t work them for them.
- Fasting is simple. There are no difficult rules to remember about what to eat or not to eat, or what meds or supps to take in what quantity and when.
- Oh yeah and it’s completely free!!