Intermittent Fasting and Strength Training: Lifting Weights While On IF Diet

Ever been told by someone that skipping breakfast is bad because breakfast is the most important meal of the day?

Most people have at some point in their life—it’s a common thought out there.

But turns out, skipping breakfast might actually be to your benefit.

Intermittent fasting is an incredibly effective method for improving all sorts of health markers, but if you’ve ever tried fasting before, you can probably agree with the fact that it’s not exactly the easiest thing to do...

For many people, food is something to look forward to; it’s the highlight of most people’s day. We spend our time planning out our next meal before we even finish the one we’re eating.

But with intermittent fasting, you’re forced to abstain from food consumption for an extended period which naturally makes any form of food look that much more appealing (even if it’s something you’d normally turn your nose up at).

But despite the challenge, there’s a lot—and we mean a lot—of benefits associated with giving your digestive organs a rest every once in a while.

We’re going to cover the basics you need to know about intermittent fasting: what it is, how to do it, why it’s good for you, and how it affects your strength training progress.

What Is Intermittent Fasting?

Intermittent fasting is essentially the science of going without food. It’s the idea of rearranging your eating schedule to cycle between periods of fasting (avoiding food) and eating, with the fasting period ranging anywhere from 12 to 24 hours.

The focus isn’t so much on what you’re eating, but rather when you’re eating.

There is indeed a large body of evidence behind the benefits of intermittent fasting for everything from weight management and athletic performance to improving memory and cognitive function, insulin sensitivity, and preventing the development of chronic diseases.

Different Types Of Intermittent Fasting

Contrary to what you may think, there’s no right way or wrong way to do intermittent fasting. There’s quite a bit of margin for you to experiment and see what fasting pattern you feel best with.

But at the end of the day, it all boils down to what works for you and your lifestyle, and what you find is most beneficial for your health. And perhaps more importantly, always listen to your body.

Here are some of the most popular fasting options:

Benefits Of Fasting

You know everything you’ve been told about eating every 2-3 hours? While it may work for some people, especially those with hypoglycemic tendencies, for most people, you can throw those beliefs out the window.

Fasting dates back centuries to when our ancestors had to go extended periods without food due to scarcity.

It worked wonders for keeping them alive, and according to a large body of evidence, it works wonders for keeping us alive (and healthy!), as well.

Here’s what periods of fasting can do for you:

1. Accelerate fat loss—Not only are you likely reducing the number of calories you consume daily because of a smaller eating window, but you’re also stimulating lipolysis and fat burning when you remain in a fasted state for an extended period by modulating levels of visceral fat and adipokines, such as leptin, IL-6, TNF-α, and IGF-1 ¹.
2. Improves cognitive function—Remaining in the fasted state increases the release of brain-derived neurotrophic factor (BDNF), a protein involved in learning and memory, which helps to strengthen certain brain pathways and increase efficiency. Higher levels of BDNF may also increase the resistance of neurons to dysfunction and degeneration ^{2, 3}.
3. Improves glucose uptake and insulin sensitivity—Intermittent fasting has been shown to boost insulin-mediated glucose uptake in tissue to be utilized as fuel. It may also normalize certain biomarkers, mainly insulin and glucose, associated with chronic disease development ⁴.
4. Recycles faulty mitochondria—Mitochondria are the powerhouses of your body. Without them, you can’t make the ATP necessary to fuel biological functions in the body. Intermittent fasting stimulates a process called autophagy, which culls old and dysfunctional cells, including mitochondria, and stimulates the production of new, more functional ones ⁵.
5. Reduces inflammation—Inflammation can be a significant impingement on your athletic performance. Intermittent fasting may help to boost the body’s resistance to oxidative stress and reduce free radicals. Fasting also helps to decrease levels of pro-inflammatory cytokines and upregulate anti-inflammatory pathways ^{1, 6}.
6. Improves athletic performance—It may contradict everything you’ve heard about exercising, but fasting can actually be beneficial for your performance. The type of exercise, however, is key to differentiate between. We talk about strength training and intermittent fasting more below.

Fed vs Fasted State

To understand how intermittent fasting works and why it’s so beneficial for fat loss (and your health in general), it’s first essential to understand the difference between the fed and fasted state.

Intermittent Fasting and Exercise

There’s no doubt that intermittent fasting can be great for endurance activities and you’ll find a lot of evidence to support fasting and improved insulin sensitivity, VO2 max, and peak power.

Still, there’s limited evidence supporting fasting and strength training as an effective long-term method for gaining muscle and strength.

It’s been shown that resistance training in a fasted state has a profound impact on the post-workout anabolic response to weight training more favorably than after a fed-state.

However, this is only the case when there’s a substantial amount of carbs and protein, primarily leucine, consumed immediately following a heavy resistance training session ⁸. This is because ingestion of protein contributes directly to stimulation of muscle protein synthesis.

What’s interesting about one study conducted on the effects of Ramadan fasting on metabolic markers and muscle growth in men is that after four weeks of resistance training, there were no substantial differences noted between training in a fed state versus a fasted state in terms of muscle mass or body composition ⁸.

What they did find is that periods of fasting are beneficial for improving the body’s ability to utilize lipids during aerobic exercise to supply fuel.

Another study found that intermittent fasting was sufficient to reduce caloric intake on fasting days, but it didn’t translate into body fat reductions in most study participants.

They also found that subjects experienced similar strength adaptations, whether they ate normally or fasted ⁹.

What was of concern here was protein intake for individuals fasting, as adequate protein consumption is a mandatory part of muscle protein synthesis and thus muscle growth.

The Possible Downside

There’s one major area where intermittent fasting might fall short for strength training: testosterone and insulin-like growth factor 1 (IGF1) levels.

Both hormones are critical for muscle building, and studies indicate that time-restricted feeding causes a significant decrease in serum testosterone and IGF1 concentrations ¹⁰.

On the other hand, some studies indicate that fasting causes a dramatic increase in growth hormone secretion, but with little effect on strength increases ^{11, 12}.

What’s Better—Strength Training While Fed or Fasted?

All evidence points to the benefits of fasting for improving markers of general health and well-being, as well as those who are metabolically impaired, but when it comes to strength training, there’s not a lot of evidence to suggest it’s the best option.

Many of the benefits experienced during fasted training compared to fed training occur independently of changes in body composition or fitness levels.

While fasted training may elicit more significant changes in metabolic markers compared to fed exercise, it’s still possible to improve body composition and aerobic fitness in both states.

And while you may not gain crazy amounts of muscle lifting in a fasted state, it’s not likely that you’ll lose it either as long as you’re following a proper nutrition protocol and consuming adequate dietary protein.

With all of that said, the fact of the matter is that an intermittent fasting protocol could still be feasible for strength athletes looking to maintain mass and lean out without negatively affecting strength and muscle mass.