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The Ultimate Guide To Intermittent Fasting


By: Taylor Empey | CFT, SFN, SET, Elite Trainer Level I | Iron Allies Fitness | 3844 S. 300 E. Salt Lake City, UT 84115 | 801-263-5336 | |


The purpose of this guide is to help clarify for you what intermittent fasting is, how it works, what the research says about fasting, the benefits, and how to implement fasting into your nutrition regimen.

There are a lot of myths oriented around fasting, its safety, and efficacy. However, this guide will show you why intermittent fasting can be both safe and effective for increasing one’s health, fitness, and lean muscle mass, as well as help decrease body fat and promote more favorable health, metabolism, and body composition.


This guide is intended for the fitness and nutrition enthusiast who have a solid understanding of basic nutrition practices and how to apply them to his/her daily life. Intermittent fasting is a challenging concept for the average person, so we caution beginners. If you have any specific medical condition, eating disorder, or metabolic syndrome, you should always consult a doctor before implementing any new dietary program. It’s important to establish a healthy relationship with food before adding intensity toward any dietary habit.


Intermittent fasting is the dietary practice of purposeful calorie restriction and feeding during specific windows of the day. Intermittent Fasting has gained popularity in recent years because science is now verifying that there are many health benefits to be derived from IF.

Fasting is not a new concept by any means. It has been common practice for religious, ritualistic, mystical, ascetic, social and ethical purposes. For much of human history food has not always been readily accessible. For many of our ancestors, intermittent periods of fasting were an unavoidable fact of life. In the 21st Century, we have the opposite problem. Most of the dietary and health problems modern societies face have arisen because we have an excessive abundance of food and a culture of indiscriminate food consumption.

It is our responsibility to mindfully evaluate and regulate the quality and quantity of food that we consume. If we don’t, it is easy to get swept away by the pleasure of eating to excess and the invariable obesity and negative health effects that follow. Intermittent Fasting is one tool we can apply on our quest for better health and fitness. It allows us to replicate, in a controlled environment, how our ancestors evolved to live and survive in both periods of feast and famine for optimal metabolic functioning.


It is fair to say that most people do not like hunger and regard hunger as a negative thing that needs to be controlled. After all, hunger is your body’s way of telling you that you need to eat, right? Additionally, many gym goers are resistant to the idea of eating infrequently and restricting calories because they fear their metabolism will “slow down” and they will not be able to maintain or build muscle.

How often have you heard that you need to consume plenty of calories and eat frequently in order to “stoke the fire of your metabolism?” The belief that a steady stream of calories (especially Protein) is necessary for muscle growth has led to many athletes carting around and eating a half dozen meals or more a day for fear that the moment the calories stop their muscles are going to start to wither away.

The belief that muscles must be constantly fed is nothing more than a myth perpetrated by protein powder and bar companies to sell more products. It has absolutely no basis in science, but is now so deeply engrained in people’s minds as truth that many gym goers are afraid to test out IF and experience the benefits it offers. Instead of buying into gym mythology, look at what actual science has to say about IF and you find that IF can actually enhance the achievement of your health and fitness related goals.


• Infrequent eating can actually accelerate your fitness goals. (Note benefits above.)

• You will only know if IF will benefit you if you set aside gym mythology and test it yourself.


Despite what negative things you may have heard about fasting, or eating infrequently, there has been substantial amount of resources put into the research of a variety of intermittent fasting protocols. What has been discovered over years of research is that there are a handful of specific fasting protocols that one can implement in their nutrition regimen that will elicit a plethora of health benefits.



Muscle maintenance

Fat loss

Lean muscle development

Improved hormone levels

Increased insulin sensitivity

Increased fat metabolism

Increased leptin sensitivity

Improved ghrelin levels

Lipolysis & fat oxidation

Increased metabolic rate

Cell integrity & repair

Improved brain cell growth

Improved natural adrenaline levels

Improved glucagon levels

Increased anabolic hormone output

Increased human growth hormone levels

Increased natural testosterone levels

Improved healthy calorie partitioning


Body weight and body fat

Risk of metabolic disease


Blood pressure

Oxidative stress

Cancer risk

Blood lipid cholesterol levels

High blood glucose levels

High insulin levels


Fasting is gaining more traction in the scientific community and more researchers are studying the effects of IF in relationship to health and fitness. These researchers have identified promising theories about optimal time lengths to remain in the fasted state to operate under our secondary metabolic system that utilizes stored energy and promotes fat loss and lean muscle gain. The following are a few popular strategies that fitness enthusiasts have found success with. Each strategy has its pros and cons. It’s important to choose the fasting protocol that most closely reflects your current eating schedule.


Author: Martin Berkhan

16 Hours Fasted/8 Hours Fed

• Includes a high protein diet protocol.

• Carb cycling paired with weight training days.

• Includes Branched Chain Amino Acids (BCAAs) while doing fasted training.

• Eat the majority of calories after weight training.

• water, coffee, tea, herbal tea, vitamins, minerals, and electrolytes permitted during fasting state.


Author: Brad Pilon

1 Day Fasted/6 Days Fed

• High protein diet minimizing processed foods and carbohydrates.

• Fast for an entire 24-hour period while hydrating with plenty of water.

• Also allows a 48-hour fasting period.

• water, coffee, tea, herbal tea, vitamins, minerals, and electrolytes permitted during fasting state.


Author: Ori Hofmekler

20 Hours Fasted/4 Hours Fed

• Allows for very small meals (fruits and vegetables) during fasted state.

• Prompts the individual to eat most of his/her calories within the four-hour feeding window.

• A form of fasting that aligns with circadian rhythms, which are physical, mental, and behavioral changes that follow a roughly 24-hour cycle, responding primarily to light and darkness in an organism’s environment.

• Workout and exercise during the 20-hour low-feeding period.

• water, coffee, tea, herbal tea, vitamins, minerals, and electrolytes permitted during fasting state.


Author: James B. Joshnson

16 Hours Fasted/8 Hours Fed Every Other Day

• Eat from 8 am until 8 pm on a Monday, then fast a full day on Tuesday, and eat again on Wednesday from 8 am until 8 pm.

• This protocol allows you to eat whatever types of food you want on your feeding days.

• water, coffee, tea, herbal tea, vitamins, minerals, and electrolytes permitted during fasting state.


Author: Unknown

Random Meals Skipped Throughout the Week

• Eat real foods, not processed foods.

• Eat like our ancestors did when food was scarce and they ate randomly as food was available.

• water, coffee, tea, herbal tea, vitamins, minerals, and electrolytes permitted during fasting state.


Author: Dave Asprey

High Fat Diet with 18 Hours Fasted/6 Hours Fed

• Eat from 2 pm until 8 pm.

• Drink Bulletproof Coffee in the morning.

• Bullet Proof Coffee includes grass-fed butter and MCT (Medium Chain Triglyceride) oil.

• water, coffee, tea, herbal tea, vitamins, minerals, and electrolytes permitted during fasting state.

• No coffee after 2 pm.


Author: Michael Mosley

2 Days Normal Eating/1 Day Restricted Calories/3 Days Normal Eating/ 1 Day Restricted Calories

• 5 total days of normal eating separated by restricted calorie fasting days.

• 2 days eating normal followed by your 3rd day restricting calories to only 500-600cals.

• Followed by 3 days of normal eating followed by your 7th day restricting calories to only 500-600cals.

• water, coffee, tea, herbal tea, vitamins, minerals, and electrolytes permitted during fasting state.


Have you ever been concerned that you might start to lose muscle, or your metabolism will slow if you miss a meal or get excessively hungry? Well, let’s put that concern to rest once and for all and see what science has to tell us about starvation, muscle loss and metabolism. The following is a timeline to help you understand the processes that have to take place for a person to actually go into “starvation mode” and begin catabolizing muscle tissue for energy.


• After eating, our bodies start to break down glycogen through Glycolysis. This process creates glucose.

• Thirty minutes later, blood glucose levels rise. We use glucose as our primary fuel source, and brain cells can only get energy from glucose.

• Glucose is packed into the liver and muscles, and the body stores fatty acids throughout the body for future use.

• Most of the stored energy goes to fuel muscle tissues and red blood cells while about 25% goes to the brain.

• The brain requires about 120 grams of glucose a day to operate properly.

• This glucose-burning period lasts for up to six hours. Then the “Hangry” (hungry/anger) feelings may start to take over.

• This metabolic response may be entirely different in some individuals who may have reached a state called nutritional ketosis, a metabolic state in which most of the body’s energy supply comes from ketone bodies in the blood rather than blood glucose. Ketosis, in simpler terms, is using fat for energy instead of sugar (glucose/broken down carbohydrates).

• Reaching ketosis may take anywhere from 2 to 7 days depending on body type, activity levels, and what you’re eating.


• Ketone bodies become a more important fuel source.

• They can be used by the brain as alternative metabolic fuel instead of glucose.

 DAY 3-4:

• On day 3, the brain will get about 30% of its energy from ketone bodies.

• On day 4, the brain will get about 70% of its energy from ketone bodies.

• Brain glucose energy demands drop from 120 g per day to 30 g.


• All the cells in your body will start to break down protein that releases amino acids into the bloodstream.

• Your body will reach the unfortunate phase called autophagy or muscle catabolism, in which your muscle mass starts to waste away to be used for fuel. This is the catabolic phase in which your body prioritizes muscle breakdown in order to keep you alive.


• The most immediate causes of death are by cardiac arrhythmia, heart attack, and severe electrolyte imbalances brought about by severe autophagy or muscle wasting. However, do not be alarmed, in order for most people to die of starvation it takes up to 3 weeks or longer; sometimes as long as 70 days depending on the person.


• If you have missed a couple meals or have fasted for between 24 hours and 72 hours, you are not going to lose any muscle mass. However, you may seem to lose weight on the scale from lack of food intake, water loss, and your muscles may look flatter or deflated.

• After you burn your glycogen stores your body will burn fat.

• It takes approximately 72 hours of complete fasting before your body starts breaking down muscle.

• Protein is not a preferred energy source and your muscle is a source of last resort. In fact, it is quite a poor source for energy and is used primarily for repair.

A “fed state” is the first 2 hours after eating a meal. A “fasted state” takes place approximately 12-24 hours after consuming a meal. “Starvation” is defined as 48 hours or more without any food consumption.


Short periods of controlled fasting will not result in muscle loss or slow your metabolism down. Many intermittent fasting protocols recommend fasted periods of 24 hours or less which is safely below the 72-hour threshold. Intermittent Fasting has been proven effective and safe for almost all individuals. However, there are some populations of people who should not engage in intermittent fasting without speaking with their primary care physician or a registered dietician first.


–       Type I diabetics

–       Type II diabetics who are on diabetic medications

–       Underweight individuals; especially underweight females

–       Women who are pregnant or who are planning to become pregnant

–       Males with body fat percentage at or below 5-6%

–       Females with body fat percentage at or below 13-16%

–       Individuals struggling with disordered eating patterns, eating disorders, or body image issues.


We have determined your muscles won’t waste away if you skip a meal or two, or even if you go a couple days while fasting, but now let’s answer how fasting affects protein synthesis and muscle growth for those of you who are concerned about developing more lean muscle mass vs those of you who are just wanting to maintain your current muscle mass.

When protein is synthesized or converted into muscle, your muscles will grow as long as muscle protein synthesis exceeds muscle protein breakdown. It has now become common knowledge in the fitness industry that you must consume a lot of protein, and consume it frequently, if you want to maximize muscle growth. This makes intuitive sense since protein is the key building block of muscle. But is it true? The $53 billion-dollar dietary supplement industry would like you to believe it is. Let’s look closely at some of these myths regarding protein.

MYTH: You need to eat a lot of protein to build muscle.

FACT: A pound of muscle contains approximately 100 grams of protein. Therefore, if you consume an extra 14 grams of protein each day, over and above what you need to maintain, you could conceivably add a pound of muscle each week.

MYTH: You need to eat at least 1-2+ gram of protein for each pound of bodyweight per day.

FACT: There are no studies that support this recommendation other than one study done on high intensity training athletes who consumed approximately 4g of protein per pound of body weight. However, these athletes were athletes and they were training over 4 hours per day; hardly your average fitness enthusiast or beginner looking to get leaner and healthier. The most reliable studies show a maximum benefit of protein intake at 0.67g-1.2g per pound of bodyweight for athletes; not average fitness enthusiasts or beginners.

MYTH: You can only assimilate about 30 grams of protein at one sitting, therefore consuming your protein frequently throughout the day, by eating smaller meals or by eating protein bars or shakes, will result in the best muscle growth.

(Have you ever asked where that excess “unassimilated protein” goes? Do you pee it out or does it vanish into thin air? By this logic, you should be able to eat as much protein as you would like and never gain an ounce.)

FACT: Your body can assimilate substantially more than 30 grams of protein from a single meal. Unless you are seeing leftover food or protein supplements in your toilet, your body is assimilating, absorbing, breaking down, and distributing the protein you consume.

Yes, it will take more time because a larger meal takes longer to digest. But here is the fact…any excess protein, whether it is from eating 6 smaller meals or one large meal of equal caloric value, will either be converted to glucose through a harsh process called gluconeogenesis or be stored as fat. You are better off replacing those excess protein calories with healthy fats and complex carbohydrates to better fuel your workout (as they are better energy/fuel sources than protein) or eliminate excess protein consumption altogether.

Interestingly, more recent studies are indicating that constantly flooding your body with protein may, in fact, desensitize your body to protein and reduce protein synthesis.

If this is indeed the case, the practice of doing intermittent fasting, and going for periods without protein, will actually improve your body’s sensitivity to protein and allow for better protein uptake into the muscle. In other words, this may be yet one other way that you can utilize intermittent fasting to not only increase healthy fat loss but promote increased muscle growth as well.


• Eating less than 1 gram of protein/pound of bodyweight per day will not reduce muscle growth, will not cause muscle loss, and will, in fact, allow you to eat more healthy fats and complex carbohydrates.

• Engaging in intermittent fasting and consuming less than 1g of protein per pound of body weight per day will actually increase your body’s sensitivity to protein and increase your ability to absorb and uptake protein into the muscle.

• Eating infrequent, larger meals with more than 30 grams of protein does not affect protein assimilation and does not leave the body needing more protein at frequent intervals throughout the day.

• Going for periods without eating protein may act to increase sensitivity to protein and improve protein synthesis.


The common protein consumption recommendations are not based in science but are, in fact, a way to promote the sale of protein powders, mass gainer shakes, bars, and meal replacement shakes. The only time consuming excessive amounts of protein would make any sense at all is only if you are taking synthesized anabolic hormones, or anabolic steroids. You will be healthier and improve your performance and results better by keeping your protein consumption to 0.67g-1.2g of protein per pound of body weight per day.



Your body is designed to adapt and operate efficiently during periods of food abundance and when it is scarce. In fact, your body performs at an even higher level when it experiences small amounts of stress and toxins. This concept is called hormesis.

Hormesis is a biological phenomenon whereby a beneficial effect (improved health, stress tolerance, growth or longevity) results from exposure to low doses of an agent that is otherwise toxic or lethal when given at higher doses.

Your body has a hormetic response to both exercise and fasting and because your body’s main objective

is to adapt and to stay in balance (homeostasis), introducing small, frequent, stressful, toxic agents into the body’s environment will cause your body to compensate accordingly. It compensates by becoming stronger, faster, and more resilient, thus creating a new standard to operate under. Your body is constantly fighting to achieve homeostasis within its environment to not only survive but to thrive.

One of the key tools of our body’s complex system of checks and balances is hormones. We have hormones related to both the fed and fasted state and each of these hormones have very specific roles and operating responsibilities.

What we eat, how much we eat and how often we eat affects the type and number of hormones that are released. Over time our eating habits can either enhance or blunt our responsiveness to these hormones in either a positive or negative manner.


The following hormones are produced when we eat or are in a “fed state”:


Insulin is a hormone made by the pancreas that allows your body to use sugar (glucose) from carbohydrates in food for immediate energy or to be stored as glycogen or fat for future use.

Insulin is often called the “fat storage hormone.” It signals your body to move and “lock away” excess energy in your fat cells as your body to use glucose, not fat, for energy. A condition called Insulin Resistance arises when your body becomes less sensitive to insulin.

When this takes place, additional stress is placed on your pancreas since it needs to produce more insulin to get the same job done. This also results longer periods of elevated insulin which makes it very difficult to lose fat.

The absence of glucose in your blood stream during fasted periods gives your pancreas a break and has been shown to increase insulin sensitivity and the speed at which glucose can be cleared from your bloodstream. This allows for more time for fat to be released from your cells to be burned as energy and this translates into fat loss.

The caveat here is that in order to maintain the fat loss you cannot eat excessive calories during your feeding period.


Leptin is a hormone made by fat cells that help to regulate your energy balance by inhibiting hunger. When released, leptin sends a signal to the hypothalamus in your brain that there are enough energy reserves and it’s ok to stop eating. In other words, it tells your brain that you are full.

This is why leptin is also known as the “satiety hormone.” Like insulin, the effects of leptin can also be blunted, a condition called Leptin Resistance. Excessive carbohydrates and in particular the sugar fructose (found in table sugar, soft drinks, etc.), have been attributed to leptin resistance. Those that are leptin resistant get the signal to stop eating later than people with healthy leptin sensitivity. This can lead to overeating and the storage of excess calories as fat.

Intermittent fasting has been shown to improve leptin sensitivity, which allows the “I’m full” signal to be properly received.


The following hormones are produced when we are unfed or are in a “fasted state”:


Glucagon is a hormone that acts in opposition to insulin and is also made by the pancreas. It is responsible for regulating blood sugar levels by supplying the body with energy by converting stored glycogen in the liver to glucose, which is then released into the bloodstream. Glucagon also promotes the release of stored fatty acids to be used for fuel.

During a fasted state insulin levels drop, and glucagon levels rise, setting the stage for fat loss.


Ghrelin is a hormone found in cells located around the stomach. Ghrelin acts in opposition to leptin and is responsible for stimulating appetite which is why it also known as the “hunger hormone.” During a fasted state ghrelin levels (and therefore hunger) do increase. However, in time ghrelin levels have been shown to normalize resulting in less hunger during fasted periods.


Human Growth hormone (HGH) is produced in the pituitary gland. The benefits of HGH to athletes are well known:

• Aids in muscle recovery and repair

• Improves sleeping patterns

• Increases energy and increases metabolism

• Increases lean muscle mass

• Promotes fat loss

HGH is often called the “youth hormone” or the “the fitness hormone” and HGH levels are increased by sleep, stress, exercise, and fasting. One recent study has shown that fasting triggered a dramatic rise in HGH, 1,300% in women and 2,000% in men. HGH simultaneously promotes muscle gain and fat loss. Athletes and bodybuilders have long used exogenous HGH for this very purpose. Fasting provides an opportunity to naturally stimulate a greater release of HGH in a healthy way.


There are many hormonal benefits to be derived from fasting, in particular, increased insulin and leptin sensitivity and increased HGH production.


• Less hunger

• Faster metabolism

• Increased Fat loss

• And it can also aid in more lean muscle growth


As mentioned in the introduction, this is a guide, not a one size fits all program. Your physical and emotional make-up is unique and the only way to find what works best for you is through self-experimentation using the various IF protocols presented as your guide and engaging in intuitive eating. Intuitive eating is learning how to listen to and understand the various signals your body is sending you, interpreting them appropriately and acting accordingly to those signals.


• To begin, make sure that you have a clean bill of health and no physical condition that could react adversely to periods without food. Do not begin an IF protocol if you are not cleared physically by your primary care physician.

• Keep in mind your level of physical activity. If you are training intensely and frequently, adjust your caloric intake to accommodate your activity level. You can use our custom personalized nutrition calculator to do this here:

• A good place to start for many people is the “Lean Gains” method, where you fast for 16 hours and feed the body in an 8-hour feeding window. To begin, skip what is traditionally thought of as breakfast, the morning meal, and break your fast sometime around 11am-1pm. Eat your last meal or bit of food at 7pm-9pm. Many people find that extending their sleeping fast through the morning is the easiest approach (Yes, sleeping is part of your fasting time!). Additionally, since you are doing it every day, it is easy to integrate it with your daily lifestyle. This protocol tends to be the easiest for most people to implement.

• Realize that there will likely be an adaptation period and some hunger as your body acclimates to the new eating schedule. People typically report that this hunger subsides. Pay close attention to your energy levels and your mood. If you notice severe light headedness, dizziness, nausea, or feeling faint stop your fasting protocol, eat (sugar preferably), and consult your doctor.

• Drink plenty of water. It will keep you hydrated and will fill your stomach. It is not only good for your health but will keep hunger at bay.

• Track your progress. If you goal is fat loss, measure your weight and waist circumference regularly, note fluctuations and adjust accordingly. If your goal is muscle building or strength, measure your arms, chest, thighs, etc. and keep a workout journal. For the most consistent measurements, take them first thing upon waking in the morning, before you eat or drink anything.

• If you find you are struggling after using one method of intermittent fasting for a few days, experiment with other methods until you find one that works for you.


When it comes to Intermittent Fasting, all of the protocols mentioned are backed by scientific research and obviously show many health and potential fat loss benefits. However, you need to remember that when engaging in an IF protocol there is one key rule you must follow if you want to ensure that you actually see results, health benefits, and don’t do damage to your body or metabolism; that key rule is making sure to eat an appropriate, healthy amount of calories, vitamins, minerals, fiber and other nutrients during your designated feeding window in order to ensure healthy, normal metabolic function.


Every person has so many variables and factors that contribute to their individual energy needs. Because of this, simply following general calorie recommendations is far too general for any one individual to see healthy, accurate results from. However, despite the inaccuracies of some calorie calculations, they are still important for establishing a beginning baseline measurement of where to start with your energy intake. We have developed a proprietary calculator based off scientific research to most accurately estimate your daily energy requirements and provide you an approximate margin of error. You can access that calculator here:


Please note that though these formulas account for your resting metabolic rate, the thermic effect of food, your non-exercise activity thermogenesis, your energy expenditure from physical activity, your body type, height, age, weight, gender, body fat percentage, and body mass index, they do not account for disease states, genetic factors, hormone profiles, and other individual variances. Your needs may vary.


If you want the single most accurate estimate of your individual caloric needs, locate and visit a clinic that has a “direct” or “indirect” “calorimeter. These two devices are the most accurate in determining your individual caloric needs. Just remember, these needs are in constant flux and may change on a daily basis depending on your routines. Getting an exact reading of your individual caloric needs is an estimation at best. You will need to experiment with the amount of calorie intake that best suits you and your needs.


Your resting metabolic rate is the approximate number of calories you burn on a daily basis in order to maintain normal healthy metabolic function. This is often also referred to as Basal Metabolic Rate (BMR); Though slightly different, they are essentially the same. Even if you are completely inactive and sedentary, you still need to eat this minimum number of calories in order to maintain normal health. The most important thing to remember about your RMR is that if you eat below it on a consistent chronic basis you will most likely be doing damage to your body, metabolism, and hindering your overall results. This condition is commonly referred to as ‘metabolic damage;’ or ‘starvation mode.’ Your RMR declines with age about 2% to 3% per decade. Lean Body Mass (LBM) is one of the only factors within an individual’s control to increase or decrease the RMR; this is why resistance training is so influential and imperative for a balanced fitness program.


The thermic effect of food is the approximate number of calories you burn simply during the process of digestion. Essentially the amount of food that you intake (gross calories) will not be the amount of food that enters your body (net calories). Though this amount is much smaller, it still adds up to be a significant number and many people don’t account for it when estimating daily energy needs.


Non-exercise activity thermogenesis is the number of calories you burn from all non-exercise activity; things like walking, taking the stairs, squatting down to pick something up, carrying your kids, and any other use of your body in a physical sense that is not focused exercise. This is essentially what is referred to as physical activity. You would be surprised the actual number of calories you can burn from simply moving around each day. NEAT is a large contributor to your overall daily energy needs.


Physical activity and exercise are actually two distinctly different things. Physical activity encompasses all the things described above in the NEAT section and more. Exercise is your focused, programmed, planned exercise regimen which can elicit a much different number of calories burned. This component will also be essential in determining your daily caloric need. If you are an athlete or a sedentary person who is just starting out in fitness, your energy needs are going to be quite different based off of this concept alone.


Your total daily energy expenditure (TDEE) is essentially all of the previously mentioned components combined. It is the total amount of energy you burn from all of the previously listed factors. If you keep everything you do consistent, this is the number of calories you would need to eat to maintain weight.


Now that we have explained those four primary components of estimating your metabolic energy expenditure, you will need to remember to adjust your intake based off of your goal. Whether your goal is to burn fat, build muscle, or both, we always recommend starting with focusing on increasing your lean muscle mass. This guarantees that you will build (not repress) your metabolism, increase your  fat burn potential, and avoid entering a state of metabolic damage. You should aim to consume about 250-500 calories more than your TDEE per day in order to gain muscle. If your goal is primarily fat loss, then you would need to adjust your calories to eat 500-1000 calories less than your TDEE. However, if you go into a deficit of more than 1000 calories per day you will place too much stress on your body and over time this will actually hinder your fat loss results causing stress and potential damage to your metabolism.


Exercise Post Oxygen Consumption (EPOC) is the amount of energy that is expelled after a workout above your normal daily metabolic rate. This amount of energy expenditure will vary greatly depending on the activities you engage in, but is essentially referred to as the “after-burn effect.”


As mentioned previously, calorie formulas are merely estimations at best. Your individual metabolism could vary by multiple hundreds of calories. Though the equations may be completely accurate for some, the potential margin of error has been estimated even as high as +/- 15% which is quite a large amount. Just remember that even after you calculate your RMR, TEF, NEAT, Exercise, and adjust according to your goal, you may still need to adjust your energy intake based off of a potential margin of error. This can also be affected by other factors such as stress, disease states, Exercise Post Oxygen Consumption (EPOC), etc.

One of the largest contributing factors to variance (besides physical activity) is your lean muscle mass percentage. Every time you develop more muscle your metabolism changes so the equations are merely estimates or your metabolic rate. Calculators that simply use body weight and do not take into account the amount of lean body mass a person has will produce dramatically wider margins of error.

If you have a higher ratio of lean muscle mass and a lower ratio of body fat percentage, you may want to consider using a higher range of energy intake above your metabolic estimations. For those of you who have a lower ratio of muscle mass and a much higher ratio of body fat percentage, you may want to start with a lower range of energy intake below your metabolic estimations.

Lean muscle mass requires more energy to sustain it as compared to body fat. Because of this, the more muscle you have the greater energy intake you need, and the healthier metabolism you will have. You are perfectly capable of repairing and increasing your metabolism. While on the contrary, if you do not focus on increasing your metabolism, it is perfectly possible for you to decrease and repress your metabolism. In fact, as we age, your metabolism can decrease as much as 2-3% in just a few years. This is why it is important to maintain a healthy diet and lifestyle oriented around lean muscle mass development.


The take-away message we want you to understand is that estimating calories is just that; an estimation. You need to keep your mind open to adjusting your nutritional energy intake regularly and try to find the exact sweet spot that works for you and your goal in orientation to your current lifestyle. Never just eat the same thing/amount all the time. Periodically monitor your nutrition and make appropriate adjustments based off of your individual need. Here is the link again to our proprietary custom nutrition calculator that we have developed. It is arguably one of the most accurate combinations of formulas for estimating your metabolic and nutritional needs without the use of expensive machines or clinical testing.


1) Never eat below your recommended BMR/RMR calories during your feeding window.

2) Make sure to eat an appropriate, healthy number of calories, vitamins, minerals, fiber and other nutrients during your feeding window in order to ensure healthy, normal metabolic function.

3) Never eat in a chronic deficit of more than 500-1000 calories below your daily burned calories.

4) Use our proprietary custom nutrition calculator to determine your nutritional needs:


Many people have natural concerns when it comes to Intermittent Fasting. It seems very counterintuitive to not eat when your body is telling you it’s hungry. What people often forget or don’t realize is that the body is an adaptive machine and is very capable of supplying itself with adequate energy to meet demand even when in a depleted state.

As we have seen, it takes over 72 hours before the body even reaches the metabolic process called autophagy, in which muscle tissue is broken down for energy. Unless the individual is incredibly lean to begin with and is going through a very strenuous physical event, the body does not want to use muscle tissue as a fuel source.

Overall, engaging in an appropriate intermittent fasting protocol, for 24 hours or less, will not result in muscle loss or slowing down of the metabolism, and will in fact aid in a developing healthier metabolic functioning, promote muscle growth and healthy sustainable fat loss.


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