The Beginner’s Guide to Intermittent Fasting – 2018 Update

“…But Tony the Tiger tells us that breakfast is the most important meal of the day! Grrrrrreat!”

And Tony the Tiger would NEVER lie…


This adage about breakfast has become commonplace that it’s readily and unquestionably accepted as fact:

“Want to lose weight? Make sure you start off with a healthy breakfast, so you can get that metabolism firing first thing in the morning!  “Eat breakfast like a king, lunch like a prince, and dinner like a pauper.”

“Want to lose more weight? Make sure you eat six small meals throughout the day so your metabolism stays operating at maximum capacity all day long.”

There are even studies that show those that eat earlier in the day lose more weight than those who ate later in the day or skipped a meal. [1]

So, eat breakfast to lose weight and obtain optimal health.

Case closed…right?

Maybe Not.

Maybe there’s way more to the story: what if there’s science and research that shows SKIPPING BREAKFAST (the horror! blasphemy!) is can help with optimum human performance, mental and physical health improvement, maximum muscle retention, and body fat loss?

After firmly being on “Team Breakfast” for 28 years of my life, I’ve skipped breakfast for the past 3.5 years and will most likely never go back!

I’m typing this from a secure location, just in case Tony the Tiger, The Trix Rabbit, and Toucan Sam come to beat me up.

After all, I’m going to rain on their breakfast parade with science today.

You see, we get more questions about Intermittent Fasting than any other topic at Nerd Fitness. People who are looking for the key to their weight loss struggles or who have heard about it from a celebrity or friend or on the news and want to know what it’s all about:

  • Should I do 24 hour fasts occasionally? What’s this 16/8 protocol people are on?
  • What if I work weird hours and train in the morning? Can I fast still?
  • Does fasting affect men and women differently?

These are all great questions, as this stuff can be complicated and overwhelming. If you have been struggling with weight loss all your life, Intermittent Fasting can HELP, but it needs to be part of a well balanced approach that works for your lifestyle, body type, lifestyle, experience and goals.

A big problem with Intermittent Fasting is knowing how to make it work for YOUR life. Depending on when you work, when you exercise, if you have a family to prepare meals for, it can get tricky to navigate. Not to mention that Intermittent Fasting is just a piece of the puzzle – you also need to eat better and make exercise a priority!

For that reason, I’ve done two things:

In addition to this MONSTER article on Intermittent Fasting, we ALSO offer 1-on-1 Online Coaching to help busy people like you trying to make Intermittent Fasting, exercise, and eating better fit into a chaotic day-to-day life!

You can learn more about how our online coaching program can help you, and schedule a call to see if we’re a good fit by clicking on the image below:

Let’s gooooooo!

What is intermittent fasting?

This seal does Intermittent Fasting by just eating...whenever it can catch fish.

Intermittent fasting is not a diet, but rather a dieting pattern.  

In simpler terms: it’s making a conscious decision to skip certain meals on purpose.

By fasting and then feasting on purpose, intermittent fasting generally means that you consume your calories during a specific window of the day, and choose not to eat food for a larger window of time.

There are a few different ways to take advantage of intermittent fasting, which I learned about back in the day from Martin over at LeanGains, a resource specifically built around fasted strength training:


What it is: Fasting for 16 hours and then only eating within a specific 8-hour window. For example, only eating from noon-8 PM, essentially skipping breakfast.

Some people only eat in a 6-hour window, or even a 4-hour window. This is “feasting” and “fasting” parts of your days and the most common form of Intermittent Fasting. It’s also my preferred method (3 years running).

Two examples: The top means you are skipping breakfast, the bottom means you are skipping dinner each day:

Intermittent Fasting Schedule

You can adjust this window to make it work for your life:

  • If you start eating at: 7AM, stop eating and start fasting at 3pm
  • If you start eating at: 11AM, stop eating and start fasting at 7pm
  • If you start eating at: 2PM, stop eating and start fasting at 10pm
  • If you start eating at: 6PM, stop eating and start fasting at 2AM.


Skipping two meals one day, where you are taking 24 hours off from eating. For example, eating on a normal schedule (finishing dinner at 8PM) and then not eating again until 8PM the following day.

So you would eat your normal 3 meals per day, and then occasionally pick a day to skip breakfast and lunch the next day.

If you can only do an 18 hour fast, or a 20 hour fast, or a 22 hour fast – that’s okay! Adjust with different time frames and see how your body responds.

Two examples: skipping breakfast and lunch one day of the week, and then another where you skip lunch and dinner one day, two days in a week.

How to Schedule Intermittent Fasting

Note: You can do this once a week, twice a week, or whatever works best for your life and situation.

By the way, both those weekly charts above come from our free Intermittent Fasting Starter Guide (with printable worksheets).

Most people struggle with knowing exactly when to eat and when to stop eating, and actually sticking with it. We address all of that in the Nerd Fitness Intermittent Fasting Guide you get free when you sign up for our email list in the box below:

Those are the two most popular intermittent fasting protocols, and the two we’ll be focusing on, though there are many variations of both that you can modify for yourself.

Some people eat in a 4 hour window, others do 6 or 8. Some people do 20 hour fasts or 24 hour fasts. You’ll need to experiment with them, adjust them to work for your lifestyle and goals, and see how your body responds.

Let’s first get into the science here behind Intermittent Fasting and why you should consider it!

How does intermittent fasting work?


Now, you might be thinking: “okay, so by skipping a meal, I will eat less than I normally eat on average (2 meals instead of 3), and thus I will lose weight, right?”

Yes, by cutting out an entire meal each day, you are consuming fewer calories per week – even if your two meals per day are slightly bigger than before. Overall, you’re still consuming fewer calories per day. This is highlighted in a recent JAMA study[b] in which both calorie restricted dieters and intermittent fasters lost similar amounts of weight over a year period.

That doesn’t tell the FULL story, as we already know that not all calories are created equal,  and that the timing of meals can also influence how your body reacts.

Intermittent Fasting can also help because your body operates differently when “feasting” compared to when “fasting”:

When you eat a meal, your body spends a few hours processing that food, burning what it can from what you just consumed.  Because it has all of this readily-available, easy to burn energy (thanks to the food you ate), your body will choose to use that as energy rather than the fat you have stored.  This is especially true if you just consumed carbohydrates/sugar, as your body prefers to burn sugar as energy before any other source.

During the “fasted state” (the hours in which your body is not consuming or digesting any food) your body doesn’t have a recently consumed meal to use as energy, so it is more likely to pull from the fat stored in your body as it’s the only energy source readily available.

Burning fat = win.

The same goes for working out in a “fasted” state.  Without a ready supply of glucose and glycogen to pull from (which has been depleted over the course of your fasted state, and hasn’t yet been replenished with a pre-workout meal), your body is forced to adapt and pull from the only source of energy available to it: the fat stored in your cells.

Why does this work?  Our bodies react to energy consumption (eating food) with insulin production. The more sensitive your body is to insulin, the more likely you’ll be to use the food you consume efficiently, and your body is most sensitive to insulin following a period of fasting [1].

These changes to insulin production and and sensitivity can help lead to weight loss [2] and muscle creation [3].

Next: Your glycogen (a starch stored in your muscles and liver that your body can burn as fuel when necessary) is depleted during sleep (aka during fasting), and will be depleted even further during training, which can lead to increased insulin sensitivity.

This means that a meal following your workout will be stored most efficiently.

During that period, the food you consumed will be used in a few ways: converted to glycogen and stored up in your muscles or burned as energy immediately to help with the recovery process, with minimal amounts stored as fat.

Compare this to a regular day (no intermittent fasting):  With insulin sensitivity at normal levels, the carbs and foods consumed will see full glycogen stores and enough glucose in the bloodstream, and thus be more likely to get stored as fat.

Not only that, but growth hormone is increased during fasted states (both during sleep [5]and after a period of fasting). Combine this  increased growth hormone secretion:[6], the decrease in insulin production (and thus increase in insulin sensitivity [7]), and you’re essentially priming your body for muscle growth and fat loss with intermittent fasting.

The less science-y version: Intermittent fasting can help teach your body to use the food it consumes more efficiently, and your body can learn to burn fat as fuel when you deprive it of new calories to constantly pull from (if you eat all day long).

TL/DR: For many different physiological reasons, fasting can help promote weight loss and muscle building when done properly.

I know Intermittent Fasting can be overwhelming, so I created a free guide and worksheet to help you get started on the right foot.

Sign up for the free Intermittent Fasting Starter Guide and Worksheets when you put your email in the box below:

But why does every health book say “6 small meals?”

Small plate of sausages - eat it on YOUR schedule

There are a few main reasons why diet books recommend six small meals:

1) When you eat a meal, your body does have to burn extra calories [8] just to process that meal.  So, the theory is that if you eat all day long with small meals, your body is constantly burning extra calories and your metabolism is firing at optimal capacity, right? Well, that’s not true.

Whether you eat 2000 calories spread out throughout the day, or 2000 calories in a small window, your body will burn the same number of calories processing the food [9]. So, the whole “keep your metabolism firing at optimum capacity by always eating” sounds good in principle, but reality tells a different story.

2) When you eat smaller meals, you might be less likely to overeat during your regular meals. I can definitely see some truth here, especially for people who struggle with portion control or don’t know how much food they should be eating.

However, once you educate yourself and take control of your eating, some might find that eating six times a day is very prohibitive and requires a lot of effort. I know I do. Also, because you’re eating six small meals, I’d argue that you probably never feel “full,” and you might be MORE likely to eat extra calories during each snack.

Although grounded in seemingly logical principles, the “six meals a day” doesn’t work for the reason you think it would (#1), and generally only works for people who struggle with portion control (#2).

If we think back to caveman days, we’d have been in serious trouble as a species if we had to eat every three hours. Do you think Joe Caveman pulled out his pocket sundial six times a day to consume his equally portioned meals?

Hell no! He ate when he could, endured and dealt with long periods of NOT eating (no refrigeration or food storage) and his body adapted to still function optimally enough to still go out and catch new food.

A recent study (written about in the NYT, highlighted by LeanGains) has done a great job of challenging the “six-meals-a-day” technique for weight loss [10]:

There were [no statistical] differences between the low- and high- [meal frequency] groups for adiposity indices, appetite measurements or gut peptides (peptide YY and ghrelin) either before or after the intervention. We conclude that increasing meal frequency does not promote greater body weight loss under the conditions described in the present study.

Factor in the potential physiological benefits listed in the previous section, and you got yourself some damn good science-backed evidence to consider trying Intermittent Fasting if you want to decrease body fat and build muscle.

Why intermittent fasting?

Intermittent Fasting Apple Plate

Now that we’re through a lot of the science stuff, let’s get into the reality of situation: why should you consider Intermittent Fasting?

Because it can work for your goals. Although we know that not all calories are created equal, caloric restriction plays a central role in weight loss. When you fast, you are also making it easier to restrict your total caloric intake over the course of the week, which can lead to consistent weight loss and maintenance.

Because it simplifies your day. Rather than having to prepare, pack, eat, and time your meals every 2-3 hours, you simply skip a meal or two and only worry about eating food in your eating window. It’s one less decision you have to make every day. It could allow you to enjoy bigger portioned meals (thus making your tastebuds and stomach satiated) and STILL eat fewer calories on average.

It requires less time (and potentially less money). Rather than having to prepare or purchase three to six meals a day, you only need to prepare two meals. Instead of stopping what you’re doing six times a day to eat, you simply only have to stop to eat twice. Rather than having to do the dishes six times, you only have to do them twice. Rather than having to purchase six meals a day, you only need to purchase two.

It promotes stronger insulin sensitivity and increased growth hormone secretion, two keys for weight loss and muscle gain.  Intermittent fasting helps you create a double whammy for weight loss and building a solid physique.

It can level up your brain, including positively counteracting conditions like Parkinson’s, Alzheimer’s, and dementia. As explained here in this TEDx talk by Mark Mattson, Professor at Johns Hopkins University and Chief of the Laboratory of Neurosciences at the National Institute on Aging fasting is grounded in serious research and more studies are coming out showing the benefits:

Plus, Wolverine does it:

And so does Boy George (who apparently reads Nerd Fitness!):

So if both musicians and adamantium-clawed superheroes do Intermittent Fasting, it can probably work for you too, if you can make it work for your particular lifestyle and situation! If you’ve tried implementing something like this in the past and not had success, or you’re just looking for guidance from a coach to help you implement it into your lifestyle, I hear ya!

That was the specific problem we set out to solve with our 1-on-1 Online Coaching Program: helping busy people make lifestyle changes (like Intermittent Fasting) and also build the habit of exercise. You can schedule a call with our team to learn more by clicking on the image below!

What are the drawbacks with intermittent fasting?

Fasting can leave you HUNGRY.

In my own experimentation over the past four years, I have found very few negative side effects with Intermittent Fasting. 

The biggest concern most people have is that Intermittent Fasting will lead to lower energy, focus, and the “holy crap I am hungry” feeling during the fasting period and ruin them. People are concerned that they will spend all morning being miserable because they haven’t consumed any food, and thus will be miserable at work and ineffective at whatever task it is they are working on.

The following are my thoughts and experiences, and your results may vary:

Yes, the initial transition from EATING ALL THE TIME, to intermittent fasting MIGHT be a bit of a jolt to your system; it was for me. However, once I got through the transition after a few days, my body quickly adapted and learned to function just as well only eating a few times a day.

Although I fast for 16 hours per day with no issues, the following might help assuage your fears that skipping breakfast will cause your body to eat itself and your brain to implode:

After 48-hours of fasting in a recent study [12], “cognitive performance, activity, sleep, and mood are not adversely affected in healthy humans by two days of calorie-deprivation.” You’ll be fasting for less time than that.

“So why do I feel grouchy and lethargic when I skip breakfast?” 

In this nerd’s humble opinion, a good portion of the grumpiness is a result of past eating habits. If you eat every three hours normally, and normally eat as soon as you wake up, your body will start get to get hungry every three hours as it learns and becomes used to expecting (and receiving) food every three hours.

If you eat breakfast every morning, your body is expecting to wake up and eat food.

Once you retrain your body to NOT expect food all day every day (or first thing in the morning), these side-effects become less of an issue. In addition, ghrelin (a hormone that makes you hungry [13]), is actually lowest in the mornings and decreases after a few hours of not eating too. The hunger pains will naturally pass!

Personally, I found this grumpiness subsided after a few days and now my mornings actually energize me.

It’s important to understand that Intermittent Fasting is NOT a cure-all panacea. Don’t delude yourself into thinking that if you skip breakfast and then eat 4,000 calories of candy bars for lunch and dinner that you will lose weight.

If you have an addictive relationship with food and you struggle with portion control, track your calorie intake in your meals to make sure you’re not overeating. If you skip breakfast, you might be so hungry from this that you OVEREAT for lunch and this can lead to weight gain. Again, the important thing here is that with intermittent fasting you’re eating fewer calories than normal because you’re skipping a meal every day.

Think about it in caveman terms again.  We certainly found ways to survive during periods of feast and famine, and that remains true today. imagine if you needed to eat in order to be active and alert: what would hungry cavemen do?

They would go find food, and that probably required a ton of effort. It actually takes our bodies about 84 hours of fasting [15] before our glucose levels are adversely affected. As we’re talking about small fasts (16-24 hour periods), this doesn’t concern us.

AN IMPORTANT CAVEAT: Intermittent Fasting can be more complex for people who have issues with blood sugar regulation, suffer from hypoglycemia, have diabetes, etc. If you fit into this category, check with your doctor or dietitian before adjusting your eating schedule. It also affects women differently (there’s a whole section dedicated to that below)

Can I build muscle and gain weight while intermittent fasting?

Intermittent Fasting Encourages Hypertrophy!

You’re damn right you can!

In fact, I have been intermittent fasting for the past three years while building muscle and decreasing my body fat percentage:

Intermittent Fasting Helped Steve!

I still eat roughly the same number of calories I was consuming before, but instead of eating all damn day long, I condense all of my calorie consumption into an eight hour window.

  • 11 AM Work out with heavy strength training in a fasted state.
  • 12 PM Immediately consume 1/2 of my calories for the day (a regular whole-food meal, followed by a calorie-dense homemade shake.)
  • 7 PM Consume the second portion of my calories for the day in a big dinner.
  • 8 PM – 12 PM the next day: Fast for 16 hours.

In a different method, my friend Nate Green packed on a crazy amount of muscle while fasting for a full 24 hours on Sundays – so it is possible. [16]

I’m not kidding when I say this has revolutionized how I look at muscle building and fat loss.

Ultimately, this method flies in the face of the typical “bulk and cut” techniques of overeating to build muscle (along with adding a lot of fat) before cutting calories to lose fat (along with some muscle) and settling down at a higher weight.

I prefer this method to the bulk-and-cut technique for a few reasons:

  • There’s far less of a crazy swing to your weight. If you are putting on 30 pounds and then cutting 25 to gain 5 lbs of muscle, your body is going through drastic swings of body mass. Your clothes will fit differently, you’ll have different levels of definition, and your body will wonder what the hell is going on.
  • You’re consuming less food and thus spending less money. Rather than overeating to put on 1 pound of muscle and 4 pounds of fat in a week or two, you’re aiming to eat exactly enough to put on 1 pound of muscle without adding much fat on top of it.  Yeah, it’s a delicate balance, but there’s far less swing involved. You are just slowly, steadily, and consistently building muscle and strength over many months.
  • There’s never a need to get “vacation-ready”: we all want to look good naked, right?  When you are just adding muscle, you don’t need to worry about getting your body ready before by drastically altering your diet (going on a miserable crash diet for a month). [17]
  • You can make small adjustments and stay on target. Keep your body fat percentage low, build strength and muscle, and if you happen to notice your body fat creeping up, cut back on the carbs. Within two weeks you should be back at your preferred body fat percentage and can continue the muscle building process.

A note on BCAA consumption. Martin from LeanGains [18] recommends consuming Branched Chain Amino Acids (BCAA’s) as a supplement with regards to fasted training to aid your muscles through your workout.

Personally, I used BCAAs for about 6-8 months during my initial start with fasted training (consuming them before training), though haven’t used them in the past 2+ years. I did NOT notice any adverse affects to not taking them with regards to my performance. Your value may vary!

Does intermittent fasting have different effects on men and women?

Run fast - on a fast

The quick answer is: “yes, Intermittent Fasting can affect men and women differently.” Anecdotally, I know many women that swear by Intermittent Fasting, while others have had adverse effects. Let’s dig into the science and studies.

A recent PubMed summary concluded that “fasting can be prescribed as a safe medical intervention as well as a lifestyle regimen which can improve women’s health in many folds [18].

Now, in that extract, many of the studies cited are focused on specifically calorie restriction (and not just fasting), and they also say that “future studies should address this gap by designing medically supervised fasting techniques to extract better evidence.”

Digging into the PubMed Archives brought me to the following conclusions [a]:

One small study (with 8 men and 8 women, all non-obese) resulted in the following: “Glucose response to a meal was slightly impaired in women after 3 weeks of treatment, but insulin response was unchanged. Men had no change in glucose response and a significant reduction in insulin response.”[19]

Another small study (8 women) studied the effects on their menstrual cycles after a 72 hour fast – which is significantly longer than any fast recommended in this article: “in spite of profound metabolic changes, a 72-hour fast during the follicular phase does not affect the menstrual cycle of normal cycling women.” [20].

Yet another study tracked 11 women with 72 hour fasts (again, longer than we’d recommend) and it found that “Fasting in women elicited expected metabolic responses – included increased cortisol (a stress hormone) – and apparently advanced the central circadian clock (which can throw off sleeping patterns). [21].

Those studies above, in working with small sample sizes, and different types of fasting than recommended here, would lead me to believe that fasting affects men and women differently, and that many of the weight loss benefits associated with intermittent fasting (that affect insulin and glucose responses) work positively for men and negatively for women.

There are also a series of articles[22] out there that dig into the potential reproductive health issues, stress challenges, induction of early-menopause [23] associated with fasting (and calorie restriction) for women.

Precision Nutrition recommends not attempting Intermittent Fasting as a woman if:

The challenge associated with all of this is that there aren’t enough long-term studies, with large enough sample sizes, specifically targeting female humans, with relation to the different types of Intermittent Fasting.

ALL OF THIS TO SAY: It does appear that men and women will have different experiences with intermittent fasting; we’re all unique snowflakes (yep, especially you), and your body will be affected by intermittent fasting differently than the person next to you.

There is enough evidence as cited in the articles and studies above that would give me pause to recommend Intermittent Fasting for women, especially if you are considering getting pregnant in the near term.

If you are looking to attempt intermittent fasting for weight loss reasons, my research has shown me that Intermittent Fasting could be less effective for women than men with regards to weight loss, and thus you would be wise to keep your efforts elsewhere:

  • Focusing on the total calories and quality of your food (here’s how to eat better).
  • Start exercising regularly!
  • Make sure you are getting enough sleep.

Now, if you’ve read the above warnings, you are still curious about Intermittent Fasting, and you want to give it a try as a female, that is your choice! You know your body best.

So, get blood work done, speak with your doctor and get a check-up. Give intermittent fasting a shot, track your results, and see how your body/blood work changes as a result of Intermittent Fasting and decide if it’s right for you.

Your milage may vary, so speak with a doctor or find a doctor versed in intermittent fasting protocols and treat it like an experiment on yourself!

Questions about intermittent fasting

Eat the right foods when practicing intermittent fasting!

1) “Won’t I get really hungry?”  

As explained above, this can be a result of the habits you have built for your body. If you are constantly eating or always eat the same time of day, your body can actually learn to prepare itself for food by beginning the process of insulin production and preparation for food.

After a brief adjustment period, your body can adapt to the fact that it’s only eating a few times a day. The more overweight you are, and the more often you eat, the more of an initial struggle this might be.

Remember, your body’s physical and cognitive abilities aren’t diminished as a result of fasting.[24].

2) “Where will I get my energy for my workouts? Won’t I be exhausted and not be able to complete my workouts if fasting?” 

This was a major concern of mine as well, but the research says otherwise: “Training with limited carbohydrate availability can stimulate adaptations in muscle cells to facilitate energy production via fat oxidation.”[25].

In other words, when you train in a fasted state, your body can get better at burning fat for energy when there are no carbs to pull from!

I’ll share some of my experiences, now doing heavy strength training for 3 years in a fasted state: For my first “fasted” workout or two after starting an IF protocol, it was very weird to not eat before training. However, after a few sessions, I learned that my body could certainly function (and even thrive) during my training sessions despite not eating a pre-workout meal.

Here I am pulling 385 lbs. at 175 BW after a 16 hour fast:

3) “I like the idea of fasted training, but I work a regular 9-5 or a night shift and can’t train at 11AM like you do. What am I supposed to do?”

Depending on your training schedule, lifestyle, and goals, go back to the portion above where I talk about the 16/8 protocol and simply adjust your hours of fasting and feasting. LeanGains digs into various options here, but here is really what you need to know:

  • Don’t overthink this. If you can’t train until 5pm, that’s okay. Consume a small meal for lunch, or shift your Intermittent Fasting window to eat all of your meals in the 8 hours post workout. Better to do that than abandon it as a lost cause and have 0% compliance.
  • If you are an elite athlete, speak with a coach or nutritionist about your specific concerns and expectations. Otherwise, make intermittent fasting work for you Consider trying the 24-hour protocol below instead of the 16/8 protocol.
  • If you train later in the day (say, 7pm) but break your fast before training (aka Lunch), make it a smaller meal focused around fats and protein – which should be a solid goal even if you aren’t Intermittent Fasting! Try to time your carb and big meal consumption to happen AFTER your workout.
  • If you exercise BEFORE work, but then don’t eat until lunchtime: consider a protein supplement immediately after your workout, or simply wait until lunch to start eating. See how your body responds and adjust accordingly.

Do what you can, and don’t psyche yourself out! Get started and adjust along the way.

“Won’t fasting cause muscle loss?”  

Another big concern of mine, but it turns out this fear was unfounded. We’ve been told by the supplement industry that we need to consume 30 g of protein every few hours, as that’s the most amount of protein our body can process at a time. Along with that, we’ve been told that if we don’t eat protein every few hours, our body’s muscle will start to break down to be burned as energy.

Again, NOT TRUE! Our bodies are quite adept at preserving muscle even when fasting [25], and it turns out that protein absorption by our body can take place over many many many hours. Protein consumed in a shorter period of time has no difference on the body compared to protein spread throughout the day.    

4) “What about my body going into starvation mode from not eating?” 

Now, the thought process here is that when we don’t feed ourselves, our bodies assume calories aren’t available and thus choose to store more calories than burning them, eliminating the benefits of weight loss with fasting. Fortunately, this is NOT true.

Starvation mode is real, but it is significantly overblown and sensationalized these days. It takes a dramatic amount of starvation, for a long time, before your body kicks into “starvation mode”. We’re talking about 24 hour or 16 hour fasts here, and starvation mode takes significantly longer than that.[26]

In other words: starvation mode should not be factoring into your decision here.

5) How much should I eat while intermittent fasting? 

Simple: Eat for your goals! If your goal is weight loss, you still need to consume fewer calories than you burn every day to lose weight. If your goal is bulking up, you’ll need to consume more calories than you burn every day. Intermittent Fasting isn’t a cure-all, it’s a PART of the puzzle.

To start, begin intermittent fasting and eat your normal sized meals and track your weight and performance. If you are losing weight and happy with the progress, keep doing what you’re doing! If you are NOT losing weight, you could be eating too much – track your calories for a week, and then target a 10% reduction in calories and continue.


Tips and tricks about Fasting 

hungry ant

Don’t freak out! Stop wondering: “can I fast 15 hours instead of 16?” or “what if I eat an apple during my fasted period, will that ruin everything?”  Relax. Your body is a complex piece of machinery and learns to adapt. Everything is not as cut and dry as you think.

If you want to eat breakfast one day but not another, that’s okay. If you are going for optimal aesthetic or athletic performance, I can see the need to be more rigid in your discipline, but otherwise…freaking chill out and don’t stress over minutiae! Don’t let perfect be the enemy of good.

Consider fasted walks in the morning. I found these to be very helpful in reducing body fat, and also gave my day a great start to clear my mind and prepare for the day. Simply wake up and go for a mile walk. Maybe you could even start walking to Mordor?

Listen to your body during workouts. If you get light headed, make sure you are consuming enough water. If you notice a significant drop in performance, make sure you are eating enough calories (especially fats and protein) during your feasting window. And if you feel severely “off,” pause your workout. Give yourself permission to EASE into intermittent fasting and fasted workouts. This is especially true if you are an endurance athlete.

Expect funny looks if you spend a lot of mornings with breakfast eaters.  A few weeks back I had a number of friends staying with me, and they were all completely dumbfounded when I told them I didn’t eat breakfast anymore. I tried to explain it to them but received a bunch of blank stares. Breakfast has become so enGRAINed (zing!) in our culture that NOT eating it sounds crazy.  You will get weird looks from those around you…embrace it. I still go to brunch or sit with friends, I just drink black coffee and enjoy conversation.

Stay busy.  If you are just sitting around thinking about how hungry you are, you’ll be more likely to struggle with this. For that reason, I time my fasting periods for maximum efficiency and minimal discomfort:

  • My first few hours of fasting come after consuming a MONSTER meal, where the last thing I want to think about is eating.
  • When I’m sleeping: 8 of my 16 hours are occupied by sleeping.  Tough to feel hungry when I’m dreaming about becoming a Jedi.
  • When I’m busy: After waking up, 12 hours of my fasting is already done.  I spend three hours doing my best work (while drinking a cup of black coffee), and then comes my final hour of fasting: training.

Zero-calorie beverages are okay.  I drink green tea in the morning for my caffeine kick while writing. If you want to drink water, black coffee, or tea during your fasted period, that’s okay.  Remember, don’t overthink it – keep things simple! Dr. Rhonda Patrick over at FoundMyFitness believes that a fast should stop at the first consumption of anything other than water, so experiment yourself and see how your body responds.

If you want to put milk in your coffee, or drink diet soda occasionally while fasting, I’m not going to stop you. Remember, we’re going for consistency and habit-building here – if milk or cream in your coffee makes life worth living, don’t deprive yourself.

There are MUCH bigger fish to fry with regards to getting healthy than a few calories here and there during a fast. 80% adherence that you stick with for a year is better than 100% adherence that you abandon after a month because it was too restrictive. If you’re trying to get to a minimum bodyfat percentage, you’ll need to be more strict – until then, however, do what allows you to stay compliant!

Track your results, listen to your body:  

  • Concerned about losing muscle mass?  Keep track of your strength training routines and see if you are getting stronger.
  • Buy a cheap set of body fat calipers and keep track of your body fat composition.
  • Track your calories, and see how your body changes when eating the same amount of food, but condensed into a certain window.
  • Sign up for the NF Email list in the box below and get your free Intermittent Fasting Starter Guide and Worksheets to track your progress.

Everybody will react to intermittent fasting differently; I can’t tell you how your body will react.  It’s up to you to listen to your body and see how making these adjustments change your body.

Don’t expect miracles.  Yes, intermittent fasting can potentially help you lose weight, increase insulin sensitivity and growth hormone secretion (all good things), but it is only ONE factor in hundreds that will determine your body composition and overall health.  Don’t expect to drop to 8% body fat and get ripped just by skipping breakfast.

We cover all of this in the NF Academy, but you need to focus on building healthy habits, eating better foods, and getting stronger.

This is just one tool that can contribute to your success.

To sum it all up

Intermittent fasting can potentially have some very positive benefits for somebody trying to lose weight or gain lean body mass.

Intermittent fasting can potentially have some very positive benefits for somebody trying to lose weight or gain lean body mass.

Men and women will tend to have different results, just like each individual person will have different results.  The ONLY way to find out is with self-experimentation.

There are multiple ways to “do” intermittent fasting:

  • Fast and feast regularly: Fast for a certain number of hours, then consume all calories within a certain number of hours.
  • Eat normally, then fast 1-2x a week: Consume your normal meals every day, then pick one or two days a week where you fast for 24 hours.  Eat your last meal Sunday night, and then don’t eat again until dinner the following day.
  • Fast occasionally: probably the easiest method for the person who wants to do the least amount of work. Simply skip a meal whenever it’s convenient. On the road? Skip breakfast.  Busy day at work? Skip lunch.  Eat poorly all day Saturday?  Make your first meal of the day dinner on Sunday.

After that, get started. Take photos, step on the scale, and track your progress for the next month. See how your body responds. See how your physique changes. See how your workouts change.

And then decide if it’s something you want to keep doing!

4 years later, I have no plans on going back to eating breakfast. Sorry General Mills and Dr. Kellogg!

If you’re worried about all of this stuff, or aren’t sure when to eat and stop eating, it might be worth working with a professional that can help you make sense of all of these questions and help you incorporate Intermittent Fasting into your life. 

I’ve found a lot of people struggle with knowing exactly when to eat and not eat, keeping track of their fast and feast windows, so we have our 1-on-1 Online Coaching Program. Schedule a call with our team to see if it’s a good fit for your situation!

I’d love to hear from you:

  • What are your questions with intermittent fasting?  
  • What are your concerns?
  • Have you tried intermittent fasting?
  • Have you had success with it, either with muscle gain or weight loss?

Thanks for leaving your comment, I’m excited to get the conversation started.


PS: I made a Intermittent Fasting Starter Guide to help you condense this article into an actionable worksheet you can follow. You can get yours free when you sign up in the box below:


Photo Source: seal mouth, tony the tiger, anatomy, cog, small plates, apples, fridge, ant, boy girl, kiwi

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  • Kizumi Corona

    Will I have ulcer when I use this method?

  • adam

    Is there any more pointed research on Intermittent fasting and longer endurance sports/cardio? Can you safely run for an hour needing 1200 or more calories after 16 hours of fasting without losing muscle?

  • Apache

    There is nothing that can help lose weight better than fasting; however when you start eating again its always so easy to gain weight again: it happened me twice

  • Pingback: 2018()

  • Kat

    Hi there! I really enjoyed reading this. Thanks for a really well written article. Just had a quick question regarding the frequency of eating meals within the eating window. The article advises against dividing the daily calories into six small meals over the course of the day, and instead advocates having two large meals within the eating window. Does this also apply to diving the daily calories into four or five small meals over the course of the eating window if you’re doing 16:8, rather than just having two big meals (e.g. lunch and dinner) when doing 16:8? I ask because as a pescatarian I prefer not to consume calcium with iron, as it seems to interfere with my ability to absorb non-heme iron from non-meat sources. Since I’ve been separating my calcium and iron consumption, my iron levels have been really good. I’m worried that if I’m only eating two large meals per day, then my iron absorption might decrease as I’ll have to consume the iron rich food with all my calcium (plus all the other minerals which compete for absorption).

  • Kara

    Thanks so much! This was really helpful when I started to feel discouraged after just a week, ready to take on tomorrow!

  • Samuel Isaías Barrios Tuna

    Thanks for the article, I did not know that I was doing something that would help me lose weight.
    I was normally to lazy to make breakfast on weekends or my days off. Due to my laziness, I would drink a cup of coffee with two (2) tablespoons of coffee for one (1) cup of liquid coffee, I would add skim milk to avoid heartburn or stomach issues. After, I drank my extra black coffee, I drank a 10-12 ounce cup of water to avoid dehydration.I was a but chubby (2010) so I knew that my body had an energy source. I lost 15-18 lbs but, I did notice that during the intermittent fasting was when my body showed the most improvement.
    To add some spice to my jog, I would take 2.5 lbs weights, 5 lbs weights or more and use the weights to gain upper body strength. Depending on how you use the weights while you jog, you can workout your ABS, SHOULDERS, CHEST, BACK, BICEP, TRICEP and FOREARM (forgive me if I forgot one or more muscles.) I started exercising more intensely this week, so this article will only help my transformation. Thanks

  • Johnny Bravo

    So small it’s insurmountable. Everyone would be fine with burning a pound of muscle as a protein when their burning 7-15 lbs. A week. Plus most IF is wrong “if” you want to lower your base weight. That’s the weight your body will return to after your done gaining or losing weight. It’s why it’s thought that most diets don’t work and you’ll regain it. Anyway I habe a book coming out in 2018 hopefully with an absolute 100% diet to lose your weight and you’ll learn why it works how your body actually works and why the government keeps lying about diet and what we should be eating. Plus skin doesn’t bounce back it’s dissolved by the body.

  • Johnny Bravo

    That’s an old rule which is completely wrong. Your body won’t burn anything other then glucose or fat as fuel once food is digested. It use to be thought that your body would burn muscle. It’s so stupid now and most of the world still believes it.

  • Mark Mayfield

    I play basketball MWF from 5am – 630am.. I am wondering if I should eat something after that or wait until 4pm if that is my window? Common sense tells me I should, but maybe that is wrong?

  • Ondine

    Thank you so much for the informative article; my concern and question is about long term calorie restriction; a) is that part of the aim of 16:8? And if so what kind of a reduction? Say, should I eat 80% of TDEE? b) aren’t there issues with long term calorie restriction? Other sites say that it’s unrealistic long-term? (Though I feel it’s fine for me) and that it will cause your body to store more of the calories consumed? So ultimately works against you? C) how does LFHC fit into this? Is it just as effective if you’re eating (good) carbs, or should I be reducing these?

  • Matilde

    Agree with it all, except IF solved my disordered eating and took away my anorexia triggers. I eat even when I’m not hungry to stay within the feeding/calorie limits and promote healthier eating habits and metabolism. One of the major issues in general recovery from anorexia is that people can gain a massive amount of weight afterwards and then struggle all over again to lose it, perpetuating the cycle. I found it best to provide a schedule and specific rules. That’s just my experience though, others’ may differ.

  • Elizabeth

    Great article.
    Ive been doing IF for a little over 6 months. I started at 288- now at 225, I still have about 65 more lbs to go. (im a 28 Female, 5’9) And IF is gonna take me there. I stand by it 100%.
    Your hunger feeling doesn’t bother you as much after few weeks into it. (Just think as the hunger feeling as your body eating you stored fat, lol .. it helps me)
    Water is a must !!!
    The mental clarity is awesome ! like your brain on MAX, lol is a bit hard to fall asleep in the beginning. But you learn to work w it.
    & be cautious who you tell, the american culture is so wrapped up in eating ALL the time.. lol people look at you crazy when you purposely skip a meal .
    You can also google Dr. Fung &/or Jimmy Moore. They are who i stumbled upon in the beginning researches. – Currently Starting a 7 day fast.

  • Jennifer Regis Bishop

    I take a variety of supplements, how would theses effect a 24 hour fast? Should I not take them during the fast?

  • Jason Wignall

    Great article and the most informative I’ve read. I’m just wondering, I train at 6:00pm every morning and would normally have a protein shake afterwards and then have my first meal at 12:00pm so think that I am nearly there anyway with getting to learn about fasting. HOWEVER……Do the calories in the protein shake and pre work out affect the fasting state.

  • adam

    I still take mine with my ‘meals as you imagine. I eat about every 2 hours. So I take my supplements with each ‘meals period

  • Sarah

    This is so gratifying to read!!!

    I’ve often thought back to the time of life when I lost the most weight the most easily, and it was when I was living in Vegas, single, and eating out lunch everyday with my three male co-workers. I’d eat so much at lunch (we went to all the good places–all you can eat sushi, churrascarias, barbeque) that I stopped eating dinner. I’d have maybe a small snack around 4p, just go home, and watch TV. 🙂 Then when I woke up, I’d have a carrot or an apple, and then eat a bowl of oatmeal slooowly at work. Then all of the sudden it would be lunch time again, and another AMAZING meal!

    The weight just came off, and I was perfectly satisfied with my life. I’ve long thought maybe that was an unhealthy but effective time of my life, BUT IT TURNS OUT I WAS JUST INTERMITTENT FASTING!!!!!!


    I can’t express how helpful it is to know there WAS something good going on then. It wasn’t just a fluke.

  • E KS

    I am very familiar with fasting and IF protocols (I’ve done it on and off since 2011, including during training and pregnancy- zero issues). My question is not with regards to weight loss (to me this is a byproduct, not the real reason to fast) but to the physiological benefits – dementia, Alzheimer’s, cellular autophagy, etc. I am trying to find the fasted time required in order for these events to take place. Do these benefits not kick in until 16 hours fasted, 24, 72, …? Thanks!

  • Melissa Caryer

    I have a question about the fasting process. Are we suppose to drink fluids during the fast? I plan on doing a 24 hour fast 2x a week. How much fluid should I consume and should it be just water?

  • Arielle Schmitt

    Great information! I was disappointed and felt the lead was a little buried when after 30 minutes of reading and video watching I realize this is not as affective for women. Whoomp whoomp.

  • Scott Purdy

    what do you break your 18hr fast with first? its very important to tell your body after a fast that only certain foods should be eaten after a fast. the 2nd meal should be whatever?

  • Daniel Jackson

    My question is, if I wanted to break up my fasting and feasting cycle, could I do that?
    Example: 7pm-6am Fasting, 6am-7am (protein shake after workout), 7am-12pm Fasting, 12pm-7pm feasting

    could this type of schedule work?

  • Magdalena Barnes

    I love this. My family all lives in Europe so this is basically their normal earing sced anyway. Wondering if during the food window can we split eating into 3 meals instead of 2 if it’s still in an 8 hour period? or does it have yo be 2 meals.

  • Kate Semple

    I have done IF in the past and it worked so well for me! I’m starting again but what I’m wondering about is how to mix IF and shift work. I work part time sometimes 0700-1900 and sometimes 1900-0700. When I’m on days I manage just fine. But on nights I generally have a morning meal, sleep in the middle of the day, and then have dinner with my family. And then I want another meal before midnight, and then by the wee hours I’m either too tired to care about food or I just can’t stop eating. Should I just aim to adjust my fasting window for night shifts or just let them go as a one off since I almost never do more than 1 night at a time. Suggestions?

  • Miss Apple

    I just started the 16 hour fast a week ago. I am finding that after I eat my first meal I am nauseated and feel awful. I eat Paleo, so I’m not eating a bunch of carbs and zero sugar. Any ideas on how I can avoid the nausea?

  • Adam Bland

    Hey Steve, This is such a great article that seems to cover everything so well, I cannot wait to implement it, So THANKYOU for your great knowledge and effort to share this with us, I do have one question though. for the time that we do eat what type of eating do you suggest/ meaning do we ned to eat strict within certain calories or macros (obviously not eating Mcdonalds, pizza etc, but do we need to track calories or eat within our macros or just eat generally healthy such as good clean eating of protein, fats and carbs?

  • Morgan

    Great article! I’m going to give it a try – I’m trying to lose weight, so hoping to see some nice results with fat loss. I was wondering, what are things I should eat? Is it basically eating whatever I want in moderation? Or should I still stick to a low cal diet during my meal periods?

  • brittany buzzell

    I absolutely loved this article and read every word! I have been fasting from 7pm to 11am for about 5 months now. My strength has increased considerably from when i started! From squatting 70lbs to 130 lbs, and doubling my lifting weight all together. I have to say i disagree with what it says about it not being good for women, however you do say that everyone is different. I find i do much better with less fats and more carbs, the only carbs i eat are fruit, Ezekiel bread and sweet potato. I find this works best for me! Great article, thank you!!

  • Charlene

    I’ve done “IF” in the past and it worked well for me. It was taboo then and now – go figure – almost mainstream. I am also a low carber because I am pre-diabetic. “IF” helps because fewer meals, better planning equals less carbs. This should all be an App or is it and I missed it? I am struggling to work out fasted during the week. I work 4 10’s so no time in the morning. My eat window is 1pm to 8pm I usually workout around 6pm. First meal at 1 then a small 100 cal snack at 4 – work out 6-7 then eat at 8pm (this meal is less than 5 carbs usually eggs and meats) bed at 11. Any other ideas?

  • Liregine Cayme

    I worked in graveyard shift, mostly i am sleeping during those time listed above what would be best schedule for me?

  • Caroline

    My question is if a 16-hour fast can be done daily for life. Is it healthy or is it not recommended long term? So many people freak out about this online. Thank you!

  • Gabriel Washam

    Sorry if i haven’t seen this in the article, but if the meal after breaking the fast is the one used most optimally, is there anything specific i should steer myself away from for that meal? Higher protein, lower sugar, lower fat? etc? I’m doing this mainly for weightloss.

  • Randy

    I have a couple couples regarding the plan.

    Let’s say I’m busy with work from 9am-8pm, and can only work out from 8:30pm-10pm. I’ve decided my fasting period can only be from 3pm-11pm. Will my workout be wasted since I worked out during my feasting period and not my fasting period? Also is it wise to eat before and after my workout since it is still in my feasting period?

  • Stephanie Andino

    I work night shift on the weekend then go to school during the week, any suggestions on how to make this work with my crazy schedule?

  • Alaa Abdalhaq

    It would be great if you had mentioned information about Autophagy and fasting and how great its to your health. then you would have the perfect article 🙂

  • Denise

    How often are you suppose to do the 14 day fasting schedule?

  • Mona

    Loved your article. You seem like a genuinely nice guy 🙂 Thanks

  • Scott A

    One question….Can you drink juice in the morning?? I make my own juice containing apple, lemon, carrot, tomato, sweet potato, kale and spinach. Will drinking that raise your insulin levels??

  • Andre

    What types of food are best to eat when breaking a fast for best fat burn results?

  • Stu

    If I am training at 5:30-6am during IF, does that mean I would move my “feast” window to 7:00 – 15:00? Or would I still only start to eat at 13:00?! I won’t have much of a life if I’m fasting from 15:00?
    Any ideas?

  • Kathy Elsesser

    I have been doing the 16/8 fast for a few months now, and my circadian clock has definitely shifted back about 2 hours. I am sleeping better, though, and have so much energy in the mornings!

  • adam

    I personally skip my first meal of the day….and eat during my work hours. This was hard to get used to…cause everyone likes plopping on the couch after work and munching! Lol but yes I survived. I pack chicken fish etc in little food containers for work and basically only eat during my 8 hour work shift. I do have meals with the family once a week and skip the IF…lol

  • adam

    IMHO, juice breaks a fast…so no. If you consume juice, start your 8 hour eating cycle 😉

  • Natalie Costa

    This is great but it surprised me when you said to eat more protein and fats, and not carbs, if energy levels were low? Can you explain more?

  • Scott A

    Thanks for the response. That’s what I was seeing in my searches also. One more question…. I drink tea in the mornings, but I sweeten it with honey. Do you think honey would spike insulin?? I think it will, but I would like another opinion.
    I’m just trying to figure this fasting thing out. Sounds like a great plan. Hope I can get it to work for me.

  • Tracey M Hughes

    Hello! How do macros factor into this? I
    count my macros and vary from high/low carb days to high/moderate/low carb days.

  • Aushyanae

    Hello, I was wondering if I have to eat during the same 8 hours everyday or can I switch up the time I fast based on the schedule day to day?

  • Sherry

    Can you have a glass or two of red wine sur the non fast portion of you day?

  • Andrew – Nutrition Whit

    Excellent article, very comprehensive, I like the charts and schedules.

  • Christian

    Hi! I’m getting started on this and have a question for you. I’m used to drink a nutrional shake in the morning, my question is should I take it to brake my fast? Due to my job and workout schedule I have to break my fast around 2pm, It gives me around 18g protein, 1,6g fat and 13g carbs, and I start my workout at 3pm, after excercise I take another protein suplement for 15g protein and no fat, is ok to keep it that way? thanks in advance!