Something to keep in mind when it comes to many things in health and fitness is that more is not always better; better is better. Therefore, it seems most prudent to start off this guide to intermittent fasting with a quick re-visitation of the “meal frequency conundrum” that pervades the health/fitness world.
Most “traditional” bodybuilders and gym-goers alike practically insist on having a constant supply of amino acids at hand in case they feel like they’re “going catabolic”. It’s almost as if bodybuilders feel like their body will literally start eating away at itself if a few hours pass by without protein consumption. Naturally, these individuals insist that frequently shoveling protein down their throat is the best option, but that supposition is a little shortsighted. .
Data indicates that the body has an innate refractory period that abolishes the muscle protein synthetic response to protein/essential amino acid intake.  Hence eating protein too frequently can actually be inhibitory to the muscle-building process, which is somewhat ironic considering this has been traditional bodybuilding wisdom for decades.
The pragmatic approach to protein intake is to ingest a generous portion of leucine-rich protein (say at least 25+ grams of complete protein), allow muscle protein synthesis to work its mojo and then return to baseline levels (which can take upwards of 4-5 hours depending on the meal). Soon thereafter, ideally, you will want to ingest another protein-rich meal.
This is actually a nice segue into this guide’s main topic of interest. Read on as we cover what exactly intermittent fasting (IF) is, the benefits and drawbacks of it, how to formulate your own IF eating plan, and the most appropriate situations to consider implementing it.
If there’s one thing that the health/fitness world has taught us, it’s that fitness-enthusiasts (especially bodybuilders) like to operate in extremes. Bodybuilding and most all physique-based competitive sports thrive on superlatives - people want to be the leanest, thickest, densest, and have the biggest arms, and most aesthetic physique.
Naturally, this means these individuals will go to (often unnecessary) extreme measures to achieve those qualities. It’s not surprising then that intermittent fasting has become quite a popular dieting “movement,” if you will, in recent years.
In a nutshell, intermittent fasting is a dietary protocol where you abstain from food (i.e. fast) for a period of time every day, typically no less than 16 hours. Once the fasting period is over, you consume your daily allotment of calories/macronutrients in what is known as the “feeding window”.
Per example, if you plan on doing an 18:6 intermittent fasting protocol (which means 18 hours fasting and a 6-hour feeding window), then your schedule may look like this:
(Begin feeding ‘window’)
(End feeding ‘window’)
In this example, your feeding window will end near bedtime, meaning you’re really only awake during about half of the fasting period. This makes the hunger pangs from fasting a little easier to cope with.
Many intermittent fasting enthusiasts proclaim that this pattern of “feasting and fasting” is how our ancestors ate, since they didn’t have access to food all throughout the day like most modern-day humans do. In fact, this is why many people on the Paleo Diet will also eat in an intermittent fasting fashion, as they believe it mimics the diets of humans in the Paleolithic era.
While it is true that our ancestors did often go many hours without ingesting any food/drink, it doesn’t necessarily mean we’ve evolved to go through periods of fasting and feasting. Sure, the human body does have mechanisms that allow it to survive without needing food (for a certain period of time), but surviving isn’t necessarily synonymous with thriving. The question then is, “Do humans thrive on an intermittent fasting eating pattern?”
The best way to answer this question is to break down the scientific benefits and drawbacks of intermittent fasting, and apply contextual factors to ultimately to determine who should and should not consider following an intermittent fasting regimen.
Believe it or not, there is a generous amount of scientific literature that has covered what intermittent fasting does for human health and longevity. That being said, it’s important to consider that “intermittent fasting” is not the same thing as fasting for 24+ hours. Generally, intermittent fasting is meant to be around 16-18 hours of abstaining from food (maybe slightly more or less depending on the individual and their goal).
Fasting for an extensive period of time (e.g. a whole day or more) is a very extreme way to diet and doesn’t seem very practical in the long run. People will argue that meal frequency is completely "irrelevant" and believe that essentially starving their body for 24+ hours and then pigging out (e.g. alternate-day fasting) is somehow beneficial. Starving then binging is not the point of intermittent fasting, nor is that a healthy way of living.
So with that clarification out of the way, let’s take a look at the major benefits of intermittent fasting:
That being said, most studies done on growth hormone show its anti-catabolic properties are most prominent when supraphysiological doses of GH are administered. Within normal physiological ranges, GH is likely not nearly as effective as a fat-burning hormone or as an anti-catabolic hormone.
Adiponectin’s primary physiological activity appears to be fatty acid oxidation and down-regulation of glucose production in the liver.  Obese individuals tend to have reductions in adiponectin, while lean individuals usually exhibit increases. Having low adiponectin levels can lead to conditions like insulin resistance and atherosclerosis.
A middle-of-the-road approach would be to pulse your protein intake throughout the day and then eat larger, complete meals to finish off your calorie demand at the end of the day, or shorten the fasting period to allow you more time to eat. 
The first step in creating your very own intermittent fasting diet plan is to determine your energy/nutrient needs. There are a multitude of formulas and calculators out there that can help you approximate these numbers, but a simple rule-of-thumb to determine your basal metabolic rate is to multiply your bodyweight (in pounds) by 13 or 14. From there you can adjust your calorie intake based on your goal and determine what the best macronutrient breakdown will be for your body.
As touched upon prior in this guide, your fasting window should be at least 16 hours (particularly if you’re aiming to cut body fat). However, if your goal is to build lean mass, then you might need to decrease the fasting window a tad so you can eat sufficient calories without having to eat to a point of being stuffed each meal.
Here are two intermittent fasting diet setup recommendations (one for bulking and one for cutting):
Mass Building Plan
(Begin feeding window)
(End feeding window)
(Begin eating window)
(End feeding window)
Naturally, once you have set up your diet structure, you simply need to spread out your macronutrient intake over each meal in your feeding window. If you work out during the fasting timeframe, your first me of the day should be higher in carbs and include plenty of protein as well. If you plan on training during the feeding window, eat a smaller pre-workout meal and then follow up the workout with a big meal to replenish glycogen and assist recovery. Nothing better than crushing a workout and coming home to a nice little post-workout ‘feast’.
The main takeaway point to consider is that intermittent fasting is not a magic diet or eating plan that will transform your body by itself. It is, however, a viable way to eat if you prefer to go about your day without worrying about having to carry Tupperware full of food everywhere so you can eat every two hours. In fact, the majority of people who follow an intermittent fasting lifestyle find that the relief from obsessively following the clock all day is the greatest psychological benefits. It also holds promise for individuals who can adhere to a fast-then-feast lifestyle
Moreover, intermittent fasting can work wonders for individuals who want to lose fat but struggle with controlling their calorie intake. Reason being is that it is much harder to overeat on an intermittent fasting style regimen and the periodic fasting has benefits for improving fatty acid oxidation. It also makes the cutting process a lot easier because you can still eat fairly large meals (as long as you make it through the daily fast).
On the contrary, research and anecdotal evidence indicates that only eating once or twice per day in a constricted timeframe will make the muscle-building process extremely challenging/inefficient. If your goal is to build muscle, it should seem rather intuitive that extreme periods of food abstinence are probably not conducive to that process.