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The Ultimate Guide to Intermittent Fasting

By now you’ve probably heard *at least* one person rave about intermittent fasting.

And, if you’re still wondering what it’s all about, here’s your ultimate guide.

What is intermittent fasting, exactly?

First off, let’s set the record straight: intermittent fasting is not a diet. Rather, intermittent fasting, sometimes abbreviated to IF, is simply following a regular cycle of eating and fasting.

Instead of a diet where you avoid eating certain foods, IF focuses on only eating at certain times. And I’ll be the first to admit, I’m never excited by the prospect of skipping a meal (or two), but it’s actually easier than you might imagine. Have you ever had a large dinner and then skipped breakfast the next morning? If so, congratulations, you’ve already done your first intermittent fast. Now that wasn’t too bad, was it?

The argument for intermittent fasting goes *wayyy* back to the lifestyle of our ancestors. And if you think about it, it makes sense. Ancient hunter-gatherers didn’t exactly have the capacity to store food, (aka refrigerators!) and there would have inevitably been times when food was scarce which forced periods of fasting. As we evolved away from the lifestyle of our ancestors, we didn’t do ourselves any favors (or at least not in this department!)

Fast forward to modern day, and we somehow came up with the notion that “grazing” was the best way to eat and that we should all be eating “6-8 small meals a day” if we’re on the quest for better health and an improved metabolism. However, research does not support this claim. Grazing works out just fine for cows, but isn’t so great for us humans. 

Why does intermittent fasting work?

To understand why intermittent fasting is effective, we have to delve into what happens when we eat a meal. The different food groups you consume, fat, protein and carbohydrates, are digested and turned into different “building blocks” and energy necessary for your body to function, like fatty acids which come from fats, amino acids from proteins, and glucose from carbohydrates. 

Glucose is especially important because it is the body’s energy. And in fact, all foods (not just carbs) can be converted into glucose — that’s how important it is!

After the carbohydrates are converted to glucose it is then absorbed into your bloodstream. 

Meanwhile, your pancreas is constantly sensing the amount of glucose in your bloodstream. 

When the pancreas senses the higher glucose level, it begins to release insulin into your bloodstream. This essentially tells your cells “hey! open up, here’s your energy”

The cells “unlock” absorb the glucose, your glucose levels start to decrease and the pancreas reacts by “shutting off” the insulin. 

If I lost you with any (or all!) of that — here’s the basic summary: 

  • Food becomes glucose 
  • Glucose triggers insulin 
  • Insulin unlocks cells 
  • Cells use glucose for energy 
  • Glucose and insulin levels fall

This cycle is repeated every time you eat and so your insulin levels rise and fall throughout the day.

As you can see, insulin plays a crucial role in this whole process – without it your body is unable to use glucose as energy. However, that’s not the end of the story —  insulin is necessary to convert food to energy, but insulin also causes weight gain

Insulin Resistance

Remember the cow constantly grazing and eating all day, every day? If we are constantly “grazing” our insulin levels never have the chance to fall back off. Instead of cycling between high and low glucose and insulin levels, your glucose and insulin levels remain elevated. 

This constant stimulation decreases your body’s sensitivity to insulin, eventually leading to insulin resistance. Essentially, your cells adapt to having a high level of insulin, they lose their sensitivity to insulin, and as time passes they need more and more insulin to get the “here’s your energy” memo. 

As your body releases more and more insulin to get the energy memo across, the continually elevated insulin levels slowly drive weight gain. 

So what’s to be done? How do you go about improving insulin sensitivity and lowering insulin levels? 

Here’s Where Intermittent Fasting Comes into Play

More and more research is being done on fasting intermittently. According to this study by Nils Halberg, “Regular fasting, by routinely lowering insulin levels, has been shown to significantly improve insulin sensitivity.” As insulin sensitivity improves, the body produces less insulin, and the cycle of insulin resistance begins to break. 

In his book, The Obesity Code, (which I highly recommend!) Dr. Fung states, “All foods raise insulin; therefore, the most effective method of reducing insulin is to avoid all foods.” Now, obviously, Dr. Fung isn’t suggesting you never eat again. But, he is suggesting that regularly fasting will lower insulin levels and decrease insulin resistance. 

Who Should Try Intermittent Fasting?

Intermittent fasting is safe and effective for most people. However, according to Kim Chism, “A person who is malnourished or underweight, less than 18 years of age, pregnant, or breastfeeding should not fast. If a person has gout, is taking medications, has type 1 or type 2 diabetes, or has gastroesophageal disease, they should consult their healthcare provider before fasting.” 

Additionally, if you’ve ever struggled with an eating disorder, intermittent fasting is something you shouldn’t try.

And of course, if you have any other health conditions which might be impacted by fasting, you should consult your doctor before beginning a new intermittent fasting protocol. 


Potential Side Effects 

If you jump right into intermittent fasting and fast too extremely, you could experience a hormonal imbalance. (And this does appear to be more common in women so be careful). Take it easy and start with a manageable 12 hour fast. 

As I mentioned above, intermittent fasting is not for everyone. I highly recommend checking with your doctor before trying any fast longer than 12 hours. 

Fasting Methods: 

Intermittent fasting is just an umbrella term to describe the cycle of fasting and eating. Within the “IF umbrella” there are multiple different methods you can follow. The only thing that really changes is the time of fasting vs. eating and how often you follow that cycle. And while the methods I’ve listed in this guide are the “popular ones”, keep in mind that you can adapt any method to best fit into your lifestyle, and even short consistent fasts will benefit your health.

12/12 method:

This is a great method to ease into fasting, if you’ve never fasted before this is where you should start. Fast for 12 hours then eat for 12 hours. I think an easy way to do this is finish dinner before 8:00 p.m. and wait until 8:00 a.m. the next morning to eat breakfast. Since this is a shorter fast it should be done more often – at least 5 days of the week.

16/8 method:

This is probably the most popular method and essentially entails eating dinner before 8:00 p.m. and not eating until noon the next day. For women, the fast can be shortened to 14 or 15 hours (and I’m not complaining about that!) This method is essentially not eating anything after dinner and then skipping breakfast the next morning. Most people find this method only slightly more challenging than the 12/12 method. Breakfast is something that is hard to fit into the day already — cutting it out makes your morning that much easier! Most people aim to do at least 4 of these fasts a week.

5:2 method:

Only eating 500-600 calories two (non-consecutive) days of the week and eating normally the other 5 days. Personally, I think this is challenging because eating only a little food is somehow more difficult for me than fasting outright. Also, because this method isn’t completely abstaining from food, your insulin levels won’t drop as much as with a complete fast.

Eat: Stop: Eat:

This method is the most extreme and is generally not recommended for women. (I’m throwing it out here simply for completeness in my ultimate guide to IF:)) “Eat stop eat” is a 24 hour fast and it is typically done once or twice a week. This is a fast that is obviously more difficult, and should only be done while being monitored by a doctor or with a doctor’s approval.

Again, whichever method you choose to follow, the important thing to remember is that IF should be flexed to work for you.

Listen to your body and ease into fasting — it is difficult to adjust at first. Begin with an easier goal (like the 12/12 method) and progress to a longer fast if you feel that it is working for you. Also, keep in mind that women are usually advised to keep their periods of fasting shorter than men, fasting no more than 14-15 hours. 

Guide For a typical Fasting Schedule: 

I typically do a 15 to 16 hour fast during the weekdays, and then eat as I please on the weekends (until Sunday evening when it’s back to my IF schedule.) Here’s what a typical weekday looks like:

8 p.m. finish dinner and begin fasting

*Continue drinking water*

~10:30 Go to bed (without a “midnight-snack”)

7:00 a.m. Drink a glass of cool water first thing in the morning

9:00 a.m. Coffee or Tea (no sweeteners) 

11:00 a.m. Break my fast with a small light meal

For me, this is a super do-able fast. I usually don’t notice I’m fasting until about 10:00 in the morning, and by that time my fast is almost over anyway!

tips for SUCCESSFUL intermittent fasting:

Eat normally and healthfully when your period of fasting is over — obviously if you binge cake and ice-cream after your fast the benefits of fasting are significantly reduced, if not entirely negated. Focus on eating quality whole foods to make the most out of your fasting. 

Water, tea and coffee are allowed during fasting periods, but skip the cream and sugar (even artificial sweeteners) as these will increase insulin levels and decrease the effectiveness of your fast. 

Lastly, be flexible with yourself — if you’re super hungry but you’ve only been fasting for 14.5 hours, don’t sweat that last 30 minutes, go ahead and (gently!) break your fast. 30 minutes isn’t going to make or break your success.

Suggestions to Make Fasting Easier

  • It’s important to keep busy so you aren’t tempted to snack and so that you don’t notice your hunger. When I first tried intermittent fasting I was worried about leaving the house without eating breakfast. I kept thinking, “What if I get shaky or get HANGRY?” But, after giving it a go, I found I enjoyed being out and about (read: away from the temptations of my kitchen!) and it seems to make the time pass more quickly. 
  • Drink plenty of water – drinking water will help ward off hunger. Drinking green tea has also been touted to suppress appetite, so go ahead and enjoy a cup (or two!) of green tea. Drinking coffee is also beneficial, though it doesn’t have the same appetite-suppressing effect.
  • Hunger will come and go — if you can get past the initial period of hunger it will subside for a while, probably until you’re about ready to break your fast 
  • Make it spiritual- do you practice a religion that values fasting? Christians, Muslims, Buddhists and other religions suggest periods of fasting. By shifting the focus of your fasting to something other than weight-loss or your health you might find it becomes easier

Benefits of Intermittent Fasting (Besides Weight Loss)

You may have noticed that I haven’t mentioned how much weight I’ve lost while doing IF… Seem’s like something I should have mentioned at the very beginning, right? I haven’t mentioned it because I wasn’t doing IF to lose weight — I’m a healthy weight and more interested in maintaining my weight than losing anything. However, I am pleased to say that my stomach did flatten out some, which is no small accomplishment at a year postpartum. So, weight loss aside, you might be wondering why I bother fasting?

Well, there are many benefits to fasting! I’ve listed the big ones below but this is far from a complete list of the benefits.

  • Decreased risk for cardiovascular disease (study)
  • Decreased inflammation in the body (study)
  • Reduces risk of type 2 diabetes 
  • Improves metabolism
  • Improves cognitive function, and helps individuals function better under stress and resist stress entirely. (source)
  • Helps prevent neurological disorders such as Alzheimer’s and Parkinson’s. (source)
  • Improved immune system. One study states,  “We believe widespread use of this pattern of eating could impact influenza epidemics and other communicable diseases by improving resistance to infection.” 
  • If you are striving to lose weight, anecdotal evidence suggests that you will be more likely to burn fat, especially the extra unhealthy fat around your middle, rather than burning muscle. 
  • I’ve also read that fasting has anti-aging benefits, and I don’t have a study to back that up… but I figure, it can’t hurt! 

Getting over the “Fasting is Taboo” mentality

There’s a slew of benefits to intermittent fasting… But, I’ll still admit it: fasting isn’t sexy. I love what James Clear has to say about intermittent fasting. He says,

“fasting isn’t a very marketable topic and so you’re not exposed to advertising and marketing on it very often. The result is that it seems somewhat extreme or strange, even though it’s really not.”

James Clear The Beginner’s Guide to Intermittent Fasting

It’s so true, right? Companies have nothing to gain by promoting fasting — fasting is free! And as such, it has less popularity than other diet methods which are advertised all the time. So get over the mental hurdle, and recognize that fasting isn’t taboo, and instead it’s quite simple.

There are no special foods to prepare, no calories, carbs, fats etc. to count! Another quote I like from James Clear says, “[intermittent fasting is] simple enough that you’ll actually do it, but meaningful enough that it will actually make a difference.” And that’s something I can get behind!

If you’re still not excited by the idea of intermittent fasting that’s normal! TBH I don’t know anyone who looks forward to their fasting periods. But, don’t let that deter you. Intermittent fasting is easier than you would expect, and is beneficial for almost all aspects of your health. So, what are you waiting for? Give IF a try so that the next time your friend starts raving about it, you can join in, too.

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