Intermittent Fasting and Strength Training

04.09.2018 |

Episode #5 of the course The beginner’s guide to intermittent fasting by Theo Brenner-Roach



I hope you’re ready for this one.

Before we get straight into the considerations for strength training and cardio when fasting, let’s first recap what happens in your body when you’re in a fasted state.

Here’s the breakdown:

1. When you eat a normal balanced meal with a mix of protein, carbs, and fats, your body immediately gets to work processing what you’ve just eaten.

2. In order to help you do this, your body releases insulin into the bloodstream to store the nutrients.

3. As a result, your body will use the meal you’ve just eaten as immediate energy, storing whatever it doesn’t need for future use.

4. After you’ve finished processing your meal, your insulin levels will return back to base levels, and you’ll go from storing mode back to burning energy.

Essentially, what this means is that during normal eating patterns, your body alternates between:

• a fasted state

• a fed state

During the fasted state, your body will prioritize burning stored glucose and glycogen for energy before using fat as an energy source, i.e., fat burn (if you’re in a calorie deficit).

In a fed state, your body will use the carbohydrates you’ve just eaten for energy and most likely store the fat for future use, i.e., fat gain (if you’re in a calorie surplus).

Now, when using IF, this fasting state gets increased from the 3 to 5 hours you usually have between meals to a full, uninterrupted 16 hours.

This means your body will use all its glycogen stores and then start burning fat for energy.

This is exactly what you want.

When in a calorie deficit, this process is accelerated, as you’ll generally have less glycogen on hand for your body to use before switching to fat as its energy source, potentially allowing you to burn more fat.

Now as great as this sounds, it does mean there is one major consideration when it comes to strength training in a fasted state.*

*Note that if you’re going to work out once you’ve broken your fast, this doesn’t apply to you.

This is because training in a fasted state can cause muscle loss due to an increase in protein synthesis and a lack of nutrients to fuel this process.

Muscle protein synthesis is essentially the technical way of saying your body is breaking down existing proteins (as a response to training) and then rebuilding proteins (using protein from your diet).

It is vital to the maintenance and growth of your body; without it, you wouldn’t build muscle.

When your protein intake is too low and muscle protein synthesis is high, you’re in a negative balance. This means you’re breaking down muscle faster than you can rebuild it.

The end result is muscle loss.

However, when your protein intake is sufficient and muscle protein synthesis is high, you’ll be in a positive balance. This means you’re rebuilding the muscle at a faster rate than it’s being broken down.

The end result is muscle growth.

The problem is, when you’re in a fasted state, you increase the chances that your body will use its own muscle (the leaner you are, the higher the chance) to fuel protein synthesis.

To counteract this, all you need to do is take 10g of BCAAs before your workout and then, if you’re not breaking your fast afterward, take another 10g.

Aside from that, you may experience a small drop in performance for the first three to five sessions while your body adapts to training in a fasted response, but after that, things should get back to normal.

If, at this point, you’re figuring out how you’ll make it through the fasting period, let alone manage to work out, then you won’t want to miss tomorrow’s lesson.

Tomorrow, we’re looking at how to make your fast easier and more enjoyable.


Recommended book

The FastDiet – Revised & Updated: Lose Weight, Stay Healthy, and Live Longer with the Simple Secret of Intermittent Fasting by Dr Michael Mosley et al.


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