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 the first 28 years of my life, I’ve skipped breakfast since 2014 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:

  • I hear Intermittent Fasting + The Keto Diet = Superpowers?
  • 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.

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!

Should You Do Intermittent Fasting and the Keto Diet?

I have published a crazy extensive article on the Keto Diet in case you’re not familiar with it, so here it is in a nutshell:

By only eating fat and protein, your body must adapt to run on fat for fuel instead of carbohydrates. In the absence of carbs/glucose, your body converts fats to ketones and uses them for fuel.

This process is called “ketosis,” and there are two ways for a body to enter ketosis:

  • Eating in a way that induces ketosis (very low carb, high fat).
  • Fasting…Hey, that’s what you’re reading about right now!

As many will tell you in the Reddit’s /r/Keto – and even members of our own Team Nerd Fitness:

Eating Keto + Intermittent Fasting = a great combo for simple weight loss.

We actually have an amazing success story here on Nerd Fitness, Larry, who followed our strategies, went Keto and start intermittent fasting. He ended up losing weight, getting stronger, AND overcame the challenges of rheumatoid arthritis (click on the image for his story)!

Here’s how the fasting portion of it works:

As your body enters a fast period when there are no sources of glucose energy readily available, the liver begins the process of breaking down fat into ketones. Fasting itself can trigger ketosis.

Fasting for a period of time before kicking off a Keto-friendly eating plan COULD speed your transition into the metabolic state of ketosis, and fasting intermittently while in ketosis could help you maintain that state.

I personally love fasting for the simplicity: I skip breakfast every day and train in a fasted state. It’s one less decision I have to make, it’s one less opportunity to make a bad food choice, and it helps me reach my goals.

WHY KETO + IF WORKS = eating Keto can be really challenging. And every time you eat, it’s an opportunity to do it wrong and accidentally eat foods that knock you out of ketosis. You’re also tempted to overeat. So, by skipping a meal, you’re eliminating one meal, one decision, one chance to screw up.

Note: if you’re thinking “Steve, am I losing weight because I’m skipping 1/3rd of my meals for the day, AND eliminating an entire macronutrient?” –

Yes. both Keto and IF have secondary effects that could also be factoring in – physiological benefits which I explain in both articles.

Your value may vary!

You need to decide what works for you. You probably won’t become “keto-adapted” (your body running on ketones) just skipping breakfast every day – your body will still have enough glucose stored from your carb-focused meals for lunch and dinner the day before.

In order to use fasting to enter ketosis, the fast needs to be long enough to deplete your carb/glucose stores, or you need to severely restrict carbohydrates from your meals in addition to IF in order to enter ketosis.

MORAL OF THE STORY: Experiment and try different strategies that will work for you. By skipping a meal or minimizing carbohydrate intake, you’re more likely than not to lose weight.

  • You can do intermittent fasting without eating a Keto Diet and lose weight.
  • You can do a Keto Diet without intermittent Fasting and lose weight. Y
  • You can combine them and lose weight.

Any of those options could work for you, but you need to make it work for your lifestyle! If you want to more about the Keto Diet, definitely read my big-ass post about Keto.

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 significantly overblown and sensationalized these days. It takes a dramatic amount of starvation, for a long, long, 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, breakfast time or the wrong side of the bed, small plates, apples, fridge, ant, boy girl, kiwi

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  • Kim Manuel

    Hi id like to ask about calorie intake and carbo intake when doing the IF. Bcos i am a lil bit confused if should i mind the calorie and carbo intakes? Thanks

  • Yessi

    Wow Thank you, Three months later I lost 34 pounds and 3 sizes, just following this system:
    >> leanbellybreakthrough1 .club << Google it
    Since I turned 40 it has been increasing harder to lose weight. I have tried every diet, watch what I ate etc., nothing worked. One day my husband came home and told me about this system, I thought why not. Three months later I lost 34 pounds and 3 sizes. Now that I’m on the maintenance part of the system I lost a total of 38 pounds and now down 4 sizes….
    This system works. It really had me change my eating habits. I have learned valuable nutritional information to ensure I keep the weight off and look great. Good Luck everyone.

  • Yessi

    Wow Thank you, Three months later I lost 34 pounds and 3 sizes, just following this system:
    Since I turned 40 it has been increasing harder to lose weight. I have tried every diet, watch what I ate etc., nothing worked. One day my husband came home and told me about this system, I thought why not. Three months later I lost 34 pounds and 3 sizes. Now that I’m on the maintenance part of the system I lost a total of 38 pounds and now down 4 sizes….
    This system works. It really had me change my eating habits. I have learned valuable nutritional information to ensure I keep the weight off and look great. Good Luck everyone.

  • Jenni Malone

    I am a fitness instructor and on Mondays and Fridays I teach back to back classes that are intense and last from 9:30 to noon. I’m worried about not eating anything and not having enough “fuel” to do these workouts. What would you recommend? Is bone broth an option before a workout like that? I’ve seen people who are getting great results with this and I know personal trainers who recommend this too. My Monday and Friday workouts are my only concern.

  • Martha Cabrera De Ferez

    The clearest way that IF is explained and suggested. Thank you so much. Starting ASAP!

  • Lilly

    I thought with IF we don’t have to ne concerned about calorie counting. I have been fasting and I eat in an 8 hr window. However i didn’t restrict to just 2 meals a day. I take my lunch at 12nn, have snacks at 3 or 5pm or basically whenever am hungry. Then my last meal at 8pm. So i guess am doing it wrong?:)

  • Ryan Rogers

    can i have my protein powder after my workout while I am in fasting? Also my workouts are usually at night around 8:00pm and my plan is to do my meals between 12 and 8 (I have a 5 year old I need to try to eat with and that can be tricky lol)

  • Sue Vreeke-Shircel

    I just started this 3 days ago I’m getting headaches and feel lethargic. I’m drinking water a lot. Is there any solutions for this I don’t want to give up??

  • Rachel

    I used to skip breakfast as a teen (I just couldn’t get the food down), and sometimes even forget to eat 1 or 2 meals (the most memorable time I skipped 2 meals on accident was a P.E. day and I felt fine). I thought it was bad back then, but now I know it’s not. Neat!

    I just started intermittent fasting 2 weeks ago. I had heard about it here and there, plus I’ve always been curious about fasting because various religions practice it and I’ve often felt that some of those widespread, ancient religious practices are rooted in something that’s beneficial for the human body. So it’s been cool to see “science” coming around to agree with “religion” on fasting.

    I waited until I wasn’t breastfeeding anymore, and then decided to finally start fasting 2 weeks ago, because I got up on Saturday and just didn’t get around to eating. Before I knew it, it was 1:00 and I was like, “Sweet! I’m going to the in-laws for the holiday supper at 3, I’ll just not eat until then!” And then the next day, I fasted all the way until 6 pm. The next weekend, I did intermittent fasting again until 6 pm on both Saturday and Sunday. So far, I like it and I think I’m going to make it a fairly regular lifestyle thing for me: intermittent fasting weekends. I go on walks every day, and I’ve been completely fine doing those while fasting.

    I’m a woman, and I haven’t personally had any ill effects from intermittent fasting (although I did wait to start trying fasting until after I wasn’t breastfeeding anymore). I haven’t had my period yet since I started the fasting practice, so I don’t know how that one will go. I know in Islam they have the women postpone their Ramadan fasting until they’re not bleeding, and I suspect there’s a good, medical reason for it (even if the layman doesn’t know what it is).

    I’m not fasting to lose weight, but just for good health. I’ve read about how fasting can help with insulin resistance, heart disease, and brain diseases. It’s also more convenient! And saves some money too, haha. It’s nice, when you’re trying to eat organic and healthy, to save some money on your grocery bill!

    I have noticed for me that if I put cream in my coffee, it “wakes up” my system and I can get symptoms of low blood sugar. But if I just get up in the morning and only have water, tea, and coffee, but no sugar or cream in it, then I’m fine.
    I do have to take it easy on the coffee though, because it’s so acidic that it starts to bother my stomach when there’s no food or cream in there to take an edge off of that acidity. But tea has been great!

    The weirdest thing has been fasting while grocery shopping (including saying no-thanks to the sample-lady), and fasting while cooking lunch for my family. But it works!
    I haven’t yet fasted while going to a restaurant with friends and family. I bet that would be weird too. I’m going on vacation soon, and I’ll have to decide if I’m going to fast (and be in a restaurant with the family), or not. (Saving a few bucks on the restaurant bill sounds nice though!)

  • Sonia

    I’ve been doing with the idea of trying IF. Been reading a lot of information about it and this is by far the most informative. I am a runner (about 30 miles a week) and also lift weights. I feel like i’m in great shape and not looking to lose weight just want to get a lot leaner. My main concern with IF is primarily losing muscle. After reading this article i’m ready to give IF a try and go from there. Thank you.

  • AJ

    Hi! I’m just starting this journey (about 2 months in) and came across this article. This goes against everything I thought I knew and have read up to this point haha. My big question is this, it is said you should not consume less than 1200 calories a day because it is “dangerous”, so my goal caloric intake is 1200 for the day which I eat over 6 small meals (to be honest I don’t always hit my calorie goal and am left a little short of what I am “suppose” to consume). So if I were to incorporate IF into my daily routine and only eat twice daily in my 8 hour window, am I consuming 600 calories per meal then or can my calories be less or even more if I’m doing the 16:8? Also, how many carbs is ideal to take in? I keep mine under or right around 100 carbs a day…fat intake I’m around 20-40 depending on my protein choice for the day…to give some personal deets, I’m female, 5’5, started out around 150lbs but have not stepped on a scale since starting my routine 2 months ago (I’ve lost some fat for sure, especially belly fat, just don’t want to start scale watching as it becomes habitual and frustrating for me), and I’m 36 years old. TYIA!!!

  • Hope Mead

    Thanks for all this info!! I go to crossfit at 6am, then work 8-4:30 so I would likely fast something like 10am-8pm and maybe eventually try to stop at 6 or 7pm. I’m confused on how to add the post-workout protein though. Would the supplement count as breaking the fast or not? Would it be detrimental to not have anything until 10am if I’m working out at 6am?

  • Chairidden

    I broke my neck 13 years ago and seen how fast other became overweight or just ‘not thin’ I started intermittent fasting that first year and haven’t stopped. So, long before it became a ‘thing’ I have partial use of my arms but no real big ‘calorie burning’ muscles. I’ve been vegan for a year now, and my Doctors tell me I’m healthier than all their other patients!!!! They don’t care how I do it, and often tell me to teach a class in both exercising will power and nutrition. Yes it works, is what I’m trying to say 😉 cheers

  • Amber Pipp

    I plan to fast from about 11-7pm or 12-8pm, but my workout tends to be around 2pm. Is this detrimental to success? Will my body adjust, or will I have less success?

  • Amber Pipp

    I interpreted the article as you should still try to get your goal calories/carbs/protein/fat in (whatever your goals are for weight loss or gain, depending), but just in that window of “feasting” time, rather than all day long.

  • Steve Meyers

    I am interested in getting started and thinking about eating from 1pm to 9pm and fasting the other hours, I am wondering if there is any best time to fast throughout a day???
    BTW, thanks for the really easy and informative web deal…

  • Steve Meyers

    Also, I am wondering what would be OK to drink while in the fasting hours… any recomendations?

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  • angelacacc

    Wow. This is so well done. I pretty much already naturally do the 16/8 but with milk in my coffee. When you said it was ok it suddenly turned my head from “I can’t fast full days” to “I can do this”
    Why a little milk in my coffee chanted everything I will never know. But thanks for giving me the confidence to start this

  • D Alejandro Carmona S

    Question. I do the 16 hour fasting and usually train at around 12pm but I break my fast at around 9:30am with some fruit and yogurt and then eat two extra meals, usually one after training and the other one at around 5:30pm. is it ok to do it this way or is it better to cut out one of the meals and just adjust the hours? Thank you

  • Matt

    The refernece to JAMA is incorrect. The journal is “JAMA Internal Medicine” which is a different journal in the family of AMA journals and has a lower impact factor. The study was cited 7 times and has a high Altmetric score because of its newsworthyness but I wouldn’t reference it as JAMA because JAMA probably wouldn’t have published that study with such a small n.

  • hemi Damania

    Thank you… really informative .
    Almost answered all my questions n doubts

  • What if I don’t want to lose weight? I’m already very petite, I’m looking to just build a healthier lifestyle and increase my strength. Is intermittent fasting for me?

  • Joseph Green

    BEST down to Earth article on intermittent fasting so far
    Well crafted and informative
    Cleared up a few doubts and dispelled some IF myths
    Been skipping lunches and feeling good
    Will start skipping Breakfast and see if I get the same results
    Thanks and recommend calorie restriction and fasting the benefits to mankind and the planet are plentiful
    Look out Food and Pharmaceutical Industries there is a revolution coming!!

  • samantha fruhling

    I can fast 15 hours but does it have to be the same hours each day? Most days I can fast from 7pm tp 10am but other days I fast at different times. Does that matter?

  • Megan

    So you explain that you can adjust your schedule to your life style. My question is, talk about skipping breakfast,..Well what if our two meals within the 8 hour window were breakfast and a late lunch,….would that still work or be the same? So I wake up at 4:30am to work out. Then I eat breakfast after, usually high protein. If I started the IF,…I would eat about 6:30am, which would mean my last meal for the day would be about 2pm or 2:30pm. Im just wondering if this is still a good plan due to a lot of your comments discussing skipping breakfast??

  • Rod Fernandez

    I started intermittent fasting in early Feb this year. doing the 3-4 routine and I’ll never go back to eating the way i was, i just wish I’ve done it earlier in my life. I have not only lost 26 lbs (in winter time) but I’ve also regulated my blood pressure, cholesterol and triglycerides without any medication!
    to me that’s incredible. my energy levels are through the roof. I’ve convinced my brother to try it and everyone else who would listen. If you workout- the results are even better.

  • Rod Fernandez

    Yes- you can have coffee or any fluids which do not contain calories-
    I find diet green tea to be a great altenative while fasting.

  • Rod Fernandez

    find your own schedule- everyone is different- but consistency matters. Stick to it and you will see results. you can modify your fasting window however you want. believe me your body will know and adjust.

  • eyka

    I would like to ask can we take pepsi during the intermittent fasting ?

  • Rod Fernandez

    You can- but not the sugary kind.
    pepsi zero is probably best since it has no calories and you can take advantage of the caffeine which helps you during training. I would limit the soda to one per day when you’re fasting.

  • Sarah Green

    How important is it to eat after a strength training workout? For example, if I’m going to fast during breakfast and lunch but I enjoy working out in the morning, is it bad for my body not to eat after my workout?

  • Nelson Luk

    hi guys, not sure if anyone is still reading this article. i want to get into intermittent fasting. im a shift worker who works at 4am-12pm. i dont usually have my first meal til after 10am and dinner before 7pm. the question is. when i work out after work (1pm-3pm) would i be burning the calories ive just eaten for brunch? i know its best to work out during the fasting period but im either at work or asleep.

  • Sam Archer

    Hey, probably a stupid question… You mentioned to drink water during the fasting but what about coffee? 🙂 And how much liquid can you consume during the fasting period.

  • Courtney Walton

    I especially appreciated the puns.

    I’m normal/athletic body type (whatever that means these days), lift 6 days a week and do cardio. I’m considering trying this after reading about the health benefits, but my main workout is at 5:30pm. Thoughts on feasting 12pm-8pm even though I work out closer to 5:30? And thoughts on best time to drink a protein shake? Bonus: I am also a vegetarian.

  • Vid Gorre

    I do IF for 4 months, what I really wonder if I could eat rice or pasta in my meals. There are some that say that I wont be fat adapted when I keep on eating it. Is this true and I should try to stay away from rice. Pls help

  • Pingback: Paleo? Keto? Slow Carb? Vegan? How to Determine the Perfect Diet For You. | Nerd Fitness()

  • wismetalman

    I’ve been trying to find information about potential long term kidney damage and cortisol level increase as well as stress management to keep the test levels up and reduce the initiation of myocatabolis. Can anyone comment on these aspects? What about vegan IF/Keto? Any tips and tricks to avoid soy and carbs while maintaining proper fat and protein intake?