How to do Intermittent Fasting

August 09, 2016

Intermittent Fasting (IF) is one of the hottest fat loss methods in fitness but like most trends fasting has been around for centuries. Upwards of 14% of adults in America have reported fasting to drop fat. In this article, I’m going to give you a crash course on IF for fat loss so that you can use it to take your fat loss to the next level when needed.

What is Intermittent Fasting

IF is the consistent practice of not eating/fasting for +12 hours at at time. The good thing about Intermittent Fasting (IF) is that it isn’t difficult to get started doing. All you need to do it not eat!

Scientists also call intermittent fasting time restricted feeding as you are restricting the time in which you are eating to a certain timeframe during the day. While it seems counterintuitive, when your body is without food, your biology shifts into high-performance mode and good things start to happen.


One immediate benefit to IF is an increase in insulin sensitivity. This is essentially your body’s ability to process and use carbohydrates. Enhancing insulin sensitivity is always a good thing. The better your insulin sensitivity, the more carbohydrates you can eat while still getting leaner.

IF also optimizes lean body hormones like growth hormone and adiponectin, the latter being a hormone released from your fat cells that will enhance your metabolic rate while further enhancing insulin sensitivity.

Another side benefit to IF is an increase in BDNF. BDNF or Brain Derived Neurotrophic Factor is a protein responsible for maintaining the health of your neurons as well as creating new ones. Stress, lack of sleep, and aging all decrease BDNF, but practicing IF can increase and potentially help normalize BDNF levels.

One Word of Warning…

At this point, you must be amped to add IF to your dieting toolkit but I must stress one point. It is important to remember that there is a difference between starving and fasting. The most effective fat loss techniques trick your body into thinking that it is in a starvation state but starving yourself as a means to lose weight is very different (and dumb). When we talk about fasting we are really talking about short-term fasting or not eating for up to 24 hours a couple times a week not chronically undereating or starving yourself.

What is fasting good for? 

People use fasting for all kinds of fat loss (beginning or advanced) but I find IF to be really good for the later stages of a fat loss diet and maintaining very lean conditioning for extended periods of time. Strategically implementing fasts into a ketogenic or low carbohydrate diet can be like adding gasoline to your fat burning furnace. At the biochemical level a ketogenic diet is fasting/starvation with the addition of protein.

I have one client that implements a weekend fast to help maintain his photoshoot ready physique in an ongoing fashion. He eats an early dinner on Friday night and then fasts until dinner on Saturday. Dinner on Saturday is usually a larger meal and since he hasn’t eaten in 24 hours he can afford to have some more calories and enjoy himself more than he normally would (he typically eats this meal out). The rest of the week he adheres to a moderate protein/high-fat diet.

Throughout the day on Saturday, every ~3 hours, he will have a serving of Modern BCAA+ and 5 grams of creatine to help maintain regular anabolic signaling to his muscles.

We started this approach as a means of helping him get leaner for a magazine photoshoot without having to make the food portions he was eating too small and it has turned into a great part of his weekly routine that has allowed him to live leaner than he expected possible.

What is fasting bad for?

Fasting is not good for building muscle or getting stronger. Have people made strength gains while following an intermittent fasting diet plan? Sure but that doesn’t mean it is optimal.  The hard reality of packing on muscle and progressively adding iron to the bar is that it is a slow and deliberate process that requires you to continually be pushing your body’s anabolic capacity with calories, training volume, progressive overload, and then recovering from it all so that you can do it again the next day. This is not a process optimized by periods of fasting.

How To Fast

There are many different ways to fast but here are 3 of the most common.

Fast Completely for 24 hours, Twice a Week.

Also commonly called Eat, Stop, Eat online, with this approach you will pick 2 non-consecutive, non-training days (low-intensity cardio days are fine if you are training 6-7 days a week) and fast for a full 24 hours on each of these days.

18-6 Fasting

Also commonly called Lean Gains online, this involves fasting for 18 hours, and eating during a 6-hour window. With this approach to fasting it is recommended that you train just prior to ending your fast so that your first meal is a post workout meal.

Modern BCAA+, No Breakfast, Late Lunch

This is a slight variation on 18-6 fasting and is the most common version of IF done by my colleagues and clients that are fitness models. They wake up early to train and drink Modern BCAA+ (1 scoop). They will continue to fast and drink BCAA (drinking the BCAA in spurts not sipping on them continuously) until 2-3 pm. Then they have a late lunch followed by a large dinner several hours later. They repeat this 360 days a year. Academically some of the intricacies of this approach could be argued but the proof is the abs.

TEAM USPlabs Dustin Starr

Coming Off Your Fast

Remember, just because you are fasting, this doesn’t mean that the rules of lean eating have changed. During your periods of feasting it is important to abide by the same science-based foundational nutrition principles that you would follow even if you weren’t fasting.

Regardless of which fasting protocol you choose (I recommend that you try them all to see which one works best for you) here are some keys to making the most of your feast periods.

Frequent Protein Spiking

Protein research shows us that we can increase muscle protein synthesis (i.e. muscle building) by eating protein rich meals every 4 hours. Other research also shows that by taking in free form essential amino acids (like the BCAA found in Modern BCAA+) that we can further stimulate protein synthesis without taking away from the effects derived from the protein rich meals we eat. When you are IF’ing the process of:

  • Protein meal
  • Wait 2 hrs
  • ModernBCAAs
  • Wait 2 hrs.
  • Protein meal
  • Wait 2 hrs
  • ModernBCAA
  • etc…

becomes even more important because the window that you are eating is smaller than it normally would be. I think this becomes more important the leaner you become.

Training vs. Not Training

I don’t recommend that you training fasted initially. One of the most important variables in fat loss training is effort. When your body is first getting accustomed to fueling itself with stored fat and carbohydrates (as it does during fasting) your energy and effort to train during or at the very end of a fast will be lacking, thus negatively impacting your fat loss progress. I recommend that you train during your feast time and not during your fast until you feel that you can put forth maximum effort. If you do choose to train during a fast, the sake of maximizing recovery, I recommend that you train at the end of your fast so that your first meal is your post workout meal.

TEAM USPlabs Amanda Gable

Eat, but Don’t Overeat

Fasting doesn’t give you permission to eat like an idiot when you are coming off your fast. Here’s your proof. Ramadan is a 30 modified fast in that food and beverages are restricted from sunrise to sunset. However, studies have shown that calorie intake before, during, and after Ramadan are comparable and a 1998 study from Appetite found no change in body weight during Ramadan. This is an important point, just because you fast doesn’t mean that you are going to lose weight. You can restrict your calories completely for 12 or 24 hours but if you then sit down and consume 3,000 calories in one sitting then all your fasting was a waste.

However, you aren’t doomed to overeating after your fast (what I call the rebound effect). A study published in the International Journal of Obesity showed that after a 36 hour fast (wake up and don’t eat until the next morning) study subjects didn’t overcompensate enough during the 36 hours post fast to accommodate for the caloric burn from the fast. The key to curbing the rebound effect was making the first post meal fast was a high-fat meal (I would add making it high protein as well would potentiate this effect). That wiped out their hunger cravings. So it seems like you can curb the caloric punch of your rebound feast by opting for higher fat foods. Do this to help with damage control post fast.

Intermittent fasting is a good diet tool to have in your toolbox as you journey to your leanest self. Follow the principles I’ve outlined above, test the different protocols that I’ve described, and determine which one works the best for you.


Dr. Mike
Dr. Mike Roussell

About Dr. Mike Roussell

Dr. Mike is known for transforming complex nutritional concepts into practical nutritional habits that his clients can use to ensure permanent weight loss and long lasting health. Dr. Mike holds a degree in biochemistry from Hobart College and a doctorate in nutrition from Pennsylvania State University.

Dr. Mike’s academic background coupled with his broad range of experience from consulting with pharmaceutical and food companies, medical schools, top rated fitness facilities, professional athletes, and individual clients, gives him the unique ability to translate scientific findings into relevant, understandable, and actionable strategies that get results.  As a scientist, his research has been published in the premiere clinical nutrition journal in the world, American Journal of Clinical Nutrition.

Dr. Mike is a sought after continuing educator, speaking across the country to physicians, dietitians, nurses, and other health professionals on the most recent advances in the nutritional treatments for cardiovascular disease.

Dr. Mike’s unique approach to scientifically derived yet practical nutrition has made him a well-known expert contributor to both national print publications and leading online fitness outlets. In addition to being an adjunct assistant professor at Pennsylvania State University, Dr. Mike serves on the Advisory Board for both Men’s Health magazine and He also writes the monthly “Ask The Nutrition Know-It-All” column for Men’s Health Magazine.  In addition to authoring three books, Your Naked Nutrition Guide (2007), The 6 Pillars of Nutrition (2011), and Dr. Mike’s Ultimate Book of Smoothies (2015) he has served as the nutritionist for Men’s Health Book of Power Training (Rodale, 2007), Strength Training Cardio (Rodale, 2010), the Women’s Health Big Book of Abs (Rodale, 2012), the Men’s Health Big Book of Abs (Rodale, 2012), and Your Body Is Your Barbell (Rodale, 2014).

The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of USPlabs or any employee thereof. Examples used within this article are only examples. USPlabs is not responsible for the accuracy of any of the information supplied by the authors of this article.  Authors may have been remunerated by USPlabs.

The information provided in this article, as well as this web-site blog is intended for informational and educational purposes only and should not be interpreted as medical advice for any condition. Always consult a qualified medical professional before beginning any nutritional program or exercise program. By reading this disclaimer, you hereby agree and understand that the information provided in this column is not medical advice and relying upon it shall be done at your sole risk.

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