Intermittent Fasting and Testosterone: The Definitive Guide

Intermittent Fasting and Testosterone: The Ultimate Guide

How Intermittent Fasting Benefits Testosterone

Intermittent fasting (IF) has played a very important role over the course of my testosterone optimization journey. Not only has it allowed me to shred stubborn belly fat and naturally optimize my hormones, but it has allowed me to do so without having to eat grilled chicken and boiled broccoli at every meal. 

Intermittent fasting is not a diet - it is merely a pattern of eating.

In this article I go over the basics of intermittent fasting, why you should consider it (especially if your aim is to naturally increase testosterone), and how to quickly implement it into your life starting today.

Let's do this.

What is Intermittent Fasting?

Intermittent Fasting boosts testosterone

Skipping breakfast. Eating everything you want for 5 days of the week, with two 24-hour fasts in between. Fitting all your meals within a 5-8 hour window.

All of the above methods fall within the realm of intermittent fasting (IF), but the essence of it remains the same:

An abstinence from caloric consumption for a particular period of time.

No calories are to be consumed during the fast (though coffee, diet soda, sugar-free gum, and calorie free sweeteners are okay, even though they contain a trace amount of calories).

You are already fasting every time you go to sleep, but with IF we extend this overnight fast in order to reap the many hormonal benefits that arise.

Intermittent Fasting Testosterone Benefits

Digestion is one of your body’s most complicated and resource intensive functions.

When you shorten your eating window and reduce the amount of times you eat in a day, your body is able to allocate more of its focus and resources on other activities like removing waste material from cells and facilitating cellular recovery.

Intermittent fasting provides a host of hormonal benefits. The following research provides further insight:

Intermittent fasting prevents acute drops in testosterone

Every time you eat something, your testosterone takes a hit (1), and this drop can remain significant past the 3-hour mark (2, 3).

If you currently follow the popular recommendation of eating 6 small meals throughout the day, just know that you're effectively causing your testosterone to plummet after each meal. 

With intermittent fasting, your meals are fit within a shorter eating window. As such, you're eating for fewer times during the day and allowing longer periods of uninterrupted testosterone secretion. 

Key Takeaway

Caloric ingestion causes a drop in testosterone. With intermittent fasting, you have fewer instances of caloric ingestion during the day, allowing testosterone to remain elevated for longer periods of time. 

Intermittent fasting amplifies growth hormone (GH) production

Fasting Boosts Growth Hormone

GH plays a crucial role in the proper growth and development of adolescents. In adults, it regulates tissue recovery, brain function, energy levels, aging, and metabolism (4).

Fasting can induce a significant increase of GH secretion - with some studies showing up to a 2000% increase  (5, 6).

The production of GH and testosterone go hand in hand - higher GH leads to higher testosterone (7).

Higher levels of GH also translate to:

  • Increased muscle and strength (8)
  • Accelerated fat-loss (9)
  • Fix erectile dysfunction (10)
  • Improved mood (11)
  • Improved sleep (12)

More GH is definitely something you want more of running through your veins. 

Key Takeaway

A short-term fast can increase growth hormone production by up to 2000%. 

Intermittent fasting may stimulate testosterone synthesis

In a study published in the European Journal of Endocrinology, researchers set out to observe the impact of a short-term fast on the androgenic hormonal concentrations in men. Blood samples were collected once before and once after a short-term fast.

Researchers found that the short-term fast increased the subjects' LH (a precursor to testosterone) response by 67% and the corresponding testosterone response by 180% (13).

Although this finding is remarkable, I would recommend that you take it with a pinch of salt. It's important to understand the difference between an acute change and a baseline change. The above study found an over-night fast to induce an acute (short-term) 180% increase in testosterone, but it's not like this increase will sustain over the long-term. Also, I was unable to find any other studies that replicate this result. 

Key Takeaway

A short-term fast can increase testosterone response by up to 180%. 

Intermittent fasting improves insulin sensitivity

Insulin is a hormone that extracts glucose from carbohydrates for your body to use for energy or to store for later use. 

Insulin sensitivity is a measure of how much insulin is required by your body to deposit a given amount of glucose. When insulin sensitivity is high, a small amount of insulin is required to lower blood glucose levels. When insulin sensitivity is low (aka insulin resistance), your body is not responding to insulin how it should and, as a result, more and more insulin is required to deposit that same amount of glucose. In extreme cases, insulin resistance can lead to type 2 diabetes. 

As it turns out, fasting is extremely beneficial for insulin sensitivity (14). A short-term fast induces a significant drop in blood sugar levels (15), meaning that your body is primed for fat-loss. Also, the food you eat is more likely to be directed towards muscle tissue rather than fat (16). 

A short-term fast also provides a lift to the hormone adiponectin (17), a hormone that can possibly reverse insulin resistance (18). 

In a study published by the American Diabetes Association, researchers found testosterone levels to be positively correlated with insulin sensitivity (19).

Key Takeaway

Intermittent fasting lowers blood sugar and improves insulin sensitivity - both of which have a positive influence on testosterone. 

Intermittent fasting can help you lost stubborn body fat

testosterone and body fat

Getting lean is the best way to naturally enhance your testosterone. This is because body fat produces an enzyme called aromatase that converts testosterone into the female sex hormone, estrogen. By lowering your body fat, you're effectively reducing the activity of aromatase and allowing more testosterone to remain unconverted. 

With intermittent fasting, you will be eating fewer meals per day. Doing so automatically facilitates a calorie deficit (unless you're pigging out at every meal). Being in a calorie deficit is the golden rule of fat-loss, and IF steps it up a notch by also boosting your metabolic rate.

Studies show that a short-term fast can increase energy expenditure by upwards of 14% (20, 21).

Intermittent fasting provides a powerful one-two punch that benefits both sides of the energy balance equation - it decreases calories in (since your eating fewer meals per day) and it increases calories out (since your metabolic rate is faster). 

An interesting study on this phenomena split 34 guys into two groups. Subjects in both groups ate the same amount of calories and were put on the same resistance training program. The only difference was how the subjects timed their meals. Subjects in the first group ate their meals at 1 p.m., 4 p.m., and 8 p.m. Subjects in the second group ate their meals at 8 a.m., 1 p.m., and 8 p.m. After 8-weeks, the subjects eating within an 8-hour window lost more body fat, while retaining the same amount of muscle (22). 

Key Takeaway

Intermittent fasting enhances your metabolism and can help you burn more calories at rest. Burning more calories at rest equals faster fat-loss. The lower your body fat, the more testosterone is allowed to remain unconverted into estrogen. 

Intermittent fasting regulates leptin

Leptin is a master hormone responsible for energy regulation.

Testosterone holds an inverse relationship with leptin - higher leptin equals lower testosterone (23).

Fasting is a proven way to bring down leptin (24).

Key Takeaway

Fasting decreases leptin - lower leptin equals higher testosterone. 

Intermittent fasting fights off oxidative stress and chronic inflammation 

Oxidative stress occurs with an increase of free radicals in the body.

Free radicals are highly reactive molecules that interact with your body's cellular structures (like protein and DNA) and damage them. If left uncontrolled, oxidative stress can speed up the aging process and lead to the development of many chronic and degenerative diseases (25). 

Research has shown intermittent fasting to be an extremely effective measure against markers of oxidative stress (26, 27). 

Chronic inflammation is another condition that causes damage on both the cell and gene level. It is linked with a host of chronic illnesses like depression, heart disease, and obesity. Chronic inflammation also elevates cortisol production. Increased cortisol is linked with decreased testosterone. Intermittent fasting helps on both of these fronts as it has been shown to significantly reduce chronic inflammation (28, 29).

Key Takeaway

Intermittent fasting can help fight off inflammation and rid your body of free radicals. 

Intermittent fasting increases cellular repair

With the millions of processes taking place in your body everyday, cells get worn out. Ideally, the body identifies these worn out cells and repairs them through a process called autophagy. In the reparation process, the cells are cleared of toxins and estrogenic chemicals. 

A high rate of autogaphy plays a preventative role against diseases such as cancer, neurodegeneration, cardiomyopathy, diabetes, liver disease, autoimmune diseases and infections (30). 

Short-term fasting significantly enhances autophagy (31).

Key Takeaway

Intermittent fasting helps rid your cells of toxins and estrogenic chemicals. 

Intermittent Fasting Quick-Start Guide

Intermittent Fasting Quick Start Guide

By now it should be clear to you why intermittent fasting is so beneficial to testosterone. Given the list of hormonal responses associated with IF, it seems like we were designed to eat this way.

Let’s now take a look at three of the most common approaches to IF and figure out which one is right for you. 

The "Just Skip Breakfast" Method

This is the simplest method of intermittent fasting and also my protocol of choice:

Simply push back your first meal 4-8 hours after waking. 

“But isn’t breakfast the most important meal of the day?”

This is what we've been told for years, but have you ever asked yourself why this is true?

Well, for starters, a number of studies have shown that breakfast eaters are less likely to be overweight and have a lower risk of chronic disease (32, 33, 34). On the flip side, breakfast skippers are more likely to be smokers, drink alcohol more frequently, have a higher body mass index, and less likely to exercise (35). 

This is why so many experts are quick to recommend breakfast as being so important. But the reality is that these are just observational studies that show a correlation and not a causation: 

Although breakfast eaters tend to be healthier and leaner, research does not prove that breakfast is the cause for their superior health. 

And if you believe that eating breakfast and many small meals throughout the day is the best way to stoke your metabolism, think again. Multiple studies have shown meal frequency to have no impact on weight-loss or metabolic rate (36, 37). 

All of this leads us to the conclusion that: 

There is nothing special about breakfast. 

Nor is there anything special about any other meal. What's most important is the amount of calories you eat, the foods they're coming from, and your macronutrient balance. 

If having breakfast in the morning energizes your day and optimizes your performance, by all means, go for it. But if you also want to implement intermittent fasting, then the 16/8 method can help you with that. 

The 16/8 Method

The 16/8 Method was pioneered by Martin Berkhan on his very popular Leangains Blog. The premise of 16/8 is simple:

Fit all your meals within an 8-hour window

16/8 is amongst the most popular and well-researched styles of IF.

Your eating window can be chosen in any 8-hour time block that suits your schedule and preferences.

If you love having breakfast or if breakfast meetings are a regular part of your day, your eating window can last anywhere from say 9-10 a.m. to about 5-6 p.m.

That said, try and keep your eating window consistent on a day-to-day basis. Ghrelin, the hunger-inducing hormone, tends to secrete based around our eating patterns. Eating at the same time everyday can help make diet adherence easier.

The Eat-Stop-Eat Method

The Eat-Stop-Eat Method of intermittent fasting was popularized by Brad Pilon

Eat regularly every day of the week, with two 24-hours in between.

In practice, you could choose Tuesday and Friday as your two fasting days. So you would eat normally till, say, 6 p.m. on a Monday and fast up until 6 p.m. the next day. You would do the same for your Friday fast.

The benefits of the Eat-Stop-Eat method are the simplicity and the metabolic resets from the 24-hour fasts.

Examples of Famous Intermittent Fasters

Intermittent fasting is a method that has been adopted by many popular celebrities and movie stars to help them drop weight for the movies. The following are some of the most popular examples. 

Terry Crews

Hugh Jackman

Joe Rogan

To Sum Up

Simply shrink the number of hours that you eat, and reap the vast benefits of optimized hormones.

To hammer home the point, a University of Utah study found that people who fasted just one day per month were 40% less likely to suffer from clogged arteries (38). There were over 500 subjects, and researchers accounted for habits like smoking, fasting, caffeine intake, and alcohol consumption. Fasting was the only habit that correlated with lower rates of heart disease. Even after adjusting for things like age, weight,diabetes, and blood pressure, the difference between fasters and non-fasters remained the same.

The first week will be difficult in adjusting to your intermittent fasting schedule. But once you find a system that suits your lifestyle and schedule, you will never have to search for another diet again.

My article has only scratched the surface of the vast topic of intermittent fasting. To learn more, check out the following best intermittent fasting resources on the internet:

Leave a Comment:

Mohamed says April 19, 2018

Excellent info , Mo !
I have observed that my power level get vastly differed with fasting as I usually do this one month per year as a religious practice from dawn to sunset (almost the same for 16/8 pattern).
Your article has nailed it and explained the phenomenal increase of power level (more specifically test-related power).

I was one of the believers of breakfast importance, but no more after your detailed article.
Thank you

    Mo Saleem says April 19, 2018

    For sure man. The people who tell you that breakfast is the most important meal of the day, ask them why. Most likely they won’t be able to answer because it is not something they’ve thought about. They just say that because it’s something that was told to them.
    Glad you enjoyed the article bro 🙂

Russ says June 5, 2018

Hey Mo,

Great article and thank you. I like to work out in the mornings but I usually eat a couple eggs and some organic fruit before. When I was a kid I want to exercise without eating or drinking anything, and got lightheaded. This is my only hesitation to perform intermittent fasting. I am also skinny and have had a fast metabolism my whole life. Maybe I can start off with lighter workouts to get used to it. Do you have any thoughts on that?

    Mo Saleem says June 6, 2018

    Hey brother,
    Personally, working out on an empty stomach hasn’t really been an issue for me. But if it makes you feel lightheaded, then I’d recommend you carry on with your eggs and fruit and simply choose an 8-hour window within which to fit all your meals. So if you’re working out at, say, 10am and having eggs and fruit at 9am then try and have your final meal before 5pm. So instead of skipping breakfast, you’re essentially skipping dinner. But yea bro, at the end of the day, you’ve got to experiment, adjust, and figure out what works for you. Hope that helps Russ.

Jean says July 17, 2018

Hi! Thank you for sharing this information on Testosterone, from all sources I’ve looked for, your site has proven to be the most reliable.

What is your opinion about ketogenic diet? I am very overweight and this diet has shown to be the only one to give results (as well as IF). I was on a less restrictive diet like LCHF, but I hit a Plateau effect and migrated to the ketogenic.

Thanks again!

    Mo Saleem says July 17, 2018

    Hey Jean,

    Appreciate your kind words.

    I’ve never tried the ketogenic diet, but based on what what I’ve read, it is very effective at driving fat-loss. That being said, it is a very strict protocol and difficult to sustain over the long-term. If you want to talk more about your current situation, you can schedule a free call with me here:

      Jean says July 18, 2018

      Unfortunately I am not fluent in English, but I can email you with my information and what I am doing.

      Thnaks and keep going with your amazing work!

        Mo Saleem says July 18, 2018

        Better yet, we can chat on fb messenger. Just click this link:

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