Intermittent fasting is an intriguing feeding pattern for human health and longevity, but there is a point where one can take this approach a bit too far. For building muscle and staying lean, it appears that “alternate-day” fasting is not the way to go.
However, acute phases of fasting (generally between 10-12 hours) do have physiological benefits, such as improved insulin sensitivity, blood glucose regulation, increased growth hormone production, etc. Extreme periods of food abstinence (such as fasting one day and eating ad libitum the next day) may actually have the inverse effects.
It’s important to note that alternate-day fasting diets “work” for weight loss mainly because they inherently reduce total calorie intake.
What is Intermittent Fasting?
At its most basic, intermittent fasting is simply a pattern of eating whereby an individual only eats in a specific timeframe (called the “eating window”) and spends the rest of the day abstaining from food (and anything containing calories). For example, if someone is following a 16:8 intermittent fasting regimen, their day might look like this:
- 8:00 AM—Wake up
- 8:00 AM – 4:00 PM— Fasting Period
(Begin eating window)
- 4:00 PM—Meal 1 (“Breakfast”)
- 7:30 PM—Meal 2
- 11:30 PM—Meal 3
(End eating window)
Therefore, this individual’s feeding window is roughly 8 hours, meaning the other 16 hours of the day are spent abstaining from food/drinks containing calories (i.e. fasting). But really this person is only awake for about half of those 16 fasting hours, making the process of going without food much easier than it appears on paper.
How to Build Muscle with Intermittent Fasting
When you consider that research suggests there is a cap to muscle protein synthesis at each feeding, it doesn’t make much sense to inhibit your ability to build muscle by fasting for excessive periods of time (e.g. 20+ hours).
The best approach to intermittent fasting, if you plan to build an appreciable amount of muscle mass, is to limit the fasting period to about 10-12 hours; this way you get the benefits of fasting but yet you don’t limit your capacity to build muscle.
Step 1: Set Your Fasting and Feeding Windows
As alluded to earlier in this article, the fasting window should ideally be around 16 hours. Some people may need to adjust it a few hours shorter or longer depending on their goal and lifestyle/schedule. If you’re trying to build muscle, it might benefit to extend the feeding window to at least 10 hours so you have an ample amount of time to get all your nutrient needs in.
Here is an intermittent fasting diet structure recommendation for building muscle:
- 7:00 AM—Wake up
- 7:00 AM – 1:00 PM— Fasting Period
(Begin eating window)
- 1:00 PM—Meal 1 (“Breakfast”)
- 4:00 PM—Meal 2
- 7:00 PM—Meal 3
- 10:30 PM—Meal 4
(End feeding window)
Step 2: Distribute Macros over the Course of Your Meals
This step should be rather intuitive, but once you’ve determined your calorie/macronutrient needs you should get a rough estimate of how much you will eat at each meal in your feeding window. There are no hard and fast rules to really live by with regards to how you portion out your macros, but it is generally advisable to eat the majority of your carbohydrates after training and in the first meal of your day.
So if you plan on training during your fasting window, then the first meal that you eat should be a bit higher in carbs and a little lower in fat, while including a generous amount of protein. Aside from that, intermittent fasting is pretty straightforward. Just make sure you eat complete meals and don’t skimp on the protein intake.
Many people generally discount intermittent fasting as a good option to build muscle, but it can in fact be a superb way to do just that. Just be sure you give yourself plenty of time to eat so you can ingest a sufficient amount of nutrients to stimulate muscle growth.
Also consider that intermittent fasting is a great option for trying to lose fat. Simply alter your calorie intake appropriately so you’re burning more than you consume and the fat will melt off!