Our Wise Guide: According to common-sense thinking, food is the same no matter when you eat it. Whether you devour a slice of cake as a midnight snack or eat it right after dinner, a calorie is a calorie – so the net effect on your body is the same. That’s the standard way of thinking – but according to Gin Stephens, it’s all wrong. The following shortform book lays out the argument of Stephens’s book that the timing of your meals can actually have a profound effect on your waistline and your overall health. Delving into a variety of different fasting regimes, as well as the science underpinning weight loss and human health, here we explore both the reasons for fasting and the day-to-day fasting tips you’ll need along the way.
Key idea 1
When it comes to fat loss, fasting beats dieting hands-down.
People sometimes think that fasting only helps you lose weight because it causes you to eat less. If you don’t eat for half the day, the thinking goes, you’ll probably end up cutting a few calories.
Over time, this undereating adds up – and, eventually, the number on the scale goes down. Sounds pretty straightforward, right?
Well, maybe – but this line of thinking ignores everything that makes fasting special. Fasting doesn’t work just by helping you to eat less. It works because it triggers some truly remarkable processes in the body.
The key message here is: When it comes to fat loss, fasting beats dieting hands-down.
One of the ways fasting helps you to lose weight is by reducing the amount of insulin circulating in your bloodstream.
Now, insulin is an important hormone; it works in tandem with glucagon to keep your blood-sugar levels in balance when you eat. But it also prevents the breakdown of your body’s reserves of fat.
So when you eat throughout the day, you keep your insulin level high – and you stop your body from tapping into your fat stores. When you fast, on the other hand, you let your insulin level drop – switching your body into fat-burning mode.
But that’s not the only reason fasting is a great weight-loss strategy. When you try to lose weight by adopting a traditional diet, your body’s natural response is to rebel. Why? Well, as far as your body can tell, you’re facing some kind of threat to your food supply.
How does your body respond to that? Simple. It boosts ghrelin, a hormone that makes you hungry, and lowers leptin, which tells you when you’ve eaten enough. In other words, it does its best to make you feel ravenous.
But that’s not all. In order to conserve energy, your body reduces its metabolic rate, or the number of calories it expends to keep you going. So while you’re trying to eat less, your body adapts and starts to require less, undoing all of your hard work.
Fasting, however, is different. Because you draw on your stored fat when you fast, your body doesn’t react as though it’s facing starvation when your food intake drops. Instead, you burn through the fat you’ve accumulated in your body – and avoid the downsides that normal diets promote.
Key idea 2
The benefits of fasting go far beyond weight loss.
So fasting can help you lose weight. For many people, that’s reason enough to try it. For others, though, who are more attached to their eating habits, fasting can seem like a drastic change to make just to drop a few pounds.
It’s a fair point. So what can you say to these people? Besides losing weight, are there any good reasons to try intermittent fasting?
The answer is a resounding yes. Every year, new research emerges revealing that the health benefits of fasting are even more extensive than previously thought.
The key message here is: The benefits of fasting go far beyond weight loss.
As you discovered in the last section, fasting can help you to reduce the level of insulin circulating in your body. This is good for weight loss – but the benefits don’t end there.
Excess insulin is linked to the development of type 2 diabetes – so when you cut your insulin level by fasting, you reduce the chance that you’ll develop this serious medical condition.
That’s not all, though. Fasting also helps tackle chronic inflammation, which can affect your overall health, causing life-threatening conditions like heart disease and cancer. In fact, a 2008 study found that people who fast for religious reasons, like Muslims during Ramadan, had significantly lower chances of developing coronary artery disease.
As if these benefits weren’t enough, fasting also supports autophagy in the body. It’s a strange word, but the process it describes is vital to your health. In short, it refers to the ability to break down and repurpose unwanted and damaged parts of your cells. Think of it like “upcycling” for your body.
By boosting autophagy, fasting helps you to avoid conditions like cancer, liver disease, and even the effects of aging, which occur when autophagy decreases.
Yes, that’s right. Fasting can help to slow aging and increase longevity. According to a 2018 review of the existing research, there’s reason to believe that fasting can, in fact, help us live younger, longer.
For those who are unconvinced by fasting’s weight-loss potential, the promise of a longer, healthier life often proves too appealing to resist.
Key idea 3
There are a number of different ways to start fasting.
So, say you’re a convert. You like the sound of losing weight, living longer, and feeling healthier. You’re on board with fasting. So what comes next?
Well, “intermittent fasting” is a catch-all term, and it’s applied to a lot of eating styles. If you’re serious about incorporating fasting into your life, you’ll need to get a handle on the various patterns and decide which one best suits you and your goals.
It’s true that the terms can be a little confusing at first. But learning about the different types of fasting is important if you’re serious about changing your lifestyle for the better.
The key message here is: There are a number of different ways to start fasting.
One of the most popular types of intermittent fasting relies on what’s called an eating window. That means that you eat only during a set number of hours every day; outside of your window, consuming calories is strictly off-limits.
People often refer to these windows in terms of ratios, with the number of fasting hours commonly being placed first. So 16:8 means 16 hours of fasting and eight of eating, whereas 19:5 means a 19-hour fast followed by a five-hour eating window.
OMAD, on the other hand, is an acronym standing for One Meal A Day. If this regime sounds extreme, bear in mind that this single “meal” is often eaten over three or four hours. You don’t have to eat your day’s entire calorie intake in 60 minutes or less!
Shorter eating windows like OMAD and 19:5 actually have more benefits than longer ones – in fact, research shows that fat-burning accelerates significantly after 18 to 24 hours of fasting.
That said, eating windows aren’t the only way to fast. There’s also the “up-and-down-day” approach. “Up days” are the days you eat, and “down days” are those you don’t. People also use ratios to refer to these eating patterns, with up days coming first – so 5:2 means five days of eating and two days of fasting.
Some people eat nothing at all on their down days. Others find it easier to have one small meal, usually of up to 500 calories.
If you go for the up-and-down-day approach, it’s worth remembering that you should eat as much as you need on your unrestricted days. In fact, the variation between up days and down days can help to prevent your body from adapting to undereating – meaning that you’ll continue to lose weight in the long run!
Key idea 4
There are a few things to avoid if you want to fast “clean.”
The notion of fasting seems pretty straightforward, right? For a certain number of hours, you just avoid eating anything. Could the idea get any simpler?
Well, yes – and there are a few qualifications and conditions that need to be mentioned, too.
Take drinks, for example. Many first-time fasters wonder what exactly they’re allowed to sip on. Is coffee permitted? Tea? What about diet soda?
If you’re beginning to ask questions like these, you’re on the right track. After all, there’s no point in denying yourself a meal only to drink the wrong thing a few hours later and undo all your effort.
The key message here is: There are a few things to avoid if you want to fast “clean.”
People in the fasting community often describe a fast that follows all the rules as a “clean” fast. In a way, it’s good to have a term like this, because it helps you to define exactly what you should be aiming for.
On the other hand, however, it’s a little misleading. Why? Because if your fast isn’t clean, it’s not really a fast at all.
Fasting clean doesn’t mean that only water may pass your lips during your fasting period – but it does narrow your choices. So what do you need to watch out for? Well, while you’re fasting, you need to steer clear of all sweetened and food-like flavors – even if they’re zero-calorie.
This tends to confuse people. Surely if something contains no calories, it can’t break your fast, right? Wrong, actually. As a matter of fact, your body experiences an insulin response to certain tastes even if they’re unaccompanied by actual calories!
One study from 2008 showed that just swishing a sweetened solution around in your mouth can significantly raise your insulin levels.
So what exactly does this information rule out? Well, all diet sodas, for a start – but also gum, flavored water, fruit-flavored teas, and anything else with a sweet or food-like taste.
Still water, sparkling water, black coffee, and plain tea are about the only things you can consume while maintaining a fast. So do stay hydrated while fasting – just don’t undermine your hard work by triggering your insulin response.
Key idea 5
To reap the greatest rewards, change your fasting style from time to time.
Once you find a fasting strategy that suits you, it can be tempting to settle into a routine.
After all, fasting isn’t always easy. You’ve got to balance your mealtimes with work commitments, family arrangements, your daily commute and much more. When you eventually find a schedule that works, you may find it all too easy to fasten onto it for good.
But if you can, resist that urge. Intermittent fasting works best when it involves variation. In order to overcome plateaus and keep your weight loss going, it’s best to throw in a curveball now and then.
The key message here is: To reap the greatest rewards, change your fasting style from time to time.
This isn’t just an opinion. Varying your fasting pattern can help to drag you out of the homeostasis to which your body is all too inclined.
Homeostasis refers to your body’s natural tendency to maintain stability and balance. If you get too hot, you sweat in order to cool yourself down. If you get too cold, you start to shiver to generate heat.
Unfortunately, homeostasis can be an obstacle when you’re trying to lose weight. Even though intermittent fasting helps avoid the metabolic dangers associated with traditional diets, your body still has the pesky habit of trying to adapt to new circumstances. Fasting helps reduce this problem – but it doesn’t do away with it entirely.
That’s where variation comes in. By mixing up your fasting pattern, you stop your body from settling into any one rhythm.
There are three main ways to do this. First of all, try switching your approach completely. If you’ve spent a month or two trying a 16:8 fasting protocol, for example, try changing to an up-and-down-day approach.
Second, try changing the length of your eating window. Why not try 19:5 on some days, and One Meal A Day on others? What matters here is keeping your body on its toes – so to speak!
Finally, try adopting a hybrid approach. In other words, fast some days, don’t restrict your eating on others, and, from time to time, make use of eating windows.
Be careful about experimenting with extended fasts, however; they can slow down the metabolism, which is the exact opposite of what you want. Having more than one down day in a row pushes you into this unfavorable territory.
Key idea 6
Fasting can help you to start eating healthily.
Intermittent fasting is a powerful tool. It’s flexible, relatively simple, and helps you to lose weight and live longer. In short, it sounds like magic – but it’s not.
Although fasting can help you to reduce your weight and improve your health, it can’t defy the laws of nature. If you overeat during your eating window, you’ll put on weight; it doesn’t matter if you’re following 16:8 or OMAD at the time.
So what’s the lesson here? It’s that fasting shouldn’t be the only change you make to your lifestyle. What you eat, and how much of it you eat, are important questions for fasters too.
The key message here is: Fasting can help you to start eating healthily.
Many people count calories in order to lose weight, but there are a few problems with this approach. One is that calories aren’t all equal.
To take just one example, your body can access the calories in cooked food more easily than those in raw food. That means you actually get more calories from baked salmon than from the same amount of raw sashimi.
Another problem is that counting calories teaches you to rely on external cues about when to stop eating, rather than listening to what your body itself is telling you.
Now, you might object that listening to your appetite is exactly what made you gain weight in the first place – and you could well be right. But intermittent fasting can help you to restore a healthy level of hunger by retraining your appetite.
A 2019 study found that just six days of 18:6 fasts reduced participants’ levels of ghrelin, the hunger hormone, and increased their rates of leptin, the hormone that makes you feel satisfied.
But that’s not all. In addition to reducing hunger, many people find that fasting actually changes their preferences in food.
So rather than hankering after unhealthy, ultra-processed foods, if you do intermittent fasting you may end up craving the kind of nourishing meals that your body really needs. That means you’ll be getting healthier both when you’re fasting and when you’re eating.
The key message in this book is the timing of your meals can have profound effects on your body, helping you to lose weight, improve your overall health – and maybe even live longer. In order to make the most of fasting, alter your eating patterns from time to time, and make sure you’re nourishing your body with healthy, satisfying foods.
If you get very hungry during a fast, set a timer – and wait.
Intermittent fasting helps you to regulate your body’s hunger hormones and to understand what your appetite is trying to tell you. So what do you do when you’re halfway into a fast and your stomach is screaming for food? You don’t want to ignore your body’s messages completely – so next time, try setting a timer for 30 minutes. Don’t eat until it rings; at that point, you should be able to tell whether you’re truly ravenous or you just had to deal with some passing hunger pangs.