Sport Nutrition

Could Intermittent Fasting Unlock Your Athletic Performance Potential?

Intermittent fasting (IF) has quickly become one of the most popular dietary trends of our modern age. I don’t meet many new clients who haven’t given IF a try, or are at least curious about it! But with all the supposed benefits we read about online, is it a worthwhile strategy for athletes? Will incorporating intermittent fasting into your nutrition strategy unlock your peak athletic performance?

Intermittent Fasting: old becomes new

The idea of fasting in and of itself is really nothing new. Many cultures and religious groups around the world have used fasting for generations for a variety of purposes. It can be as a means to connect with a higher power, or commemorate a historic event within their community. Fasting is often viewed as something that is ‘cleansing’ and good for the body, mind, and spirit.

More recently though fasting has caught the attention of some new groups of people. One being scientific researchers who want to learn more about the physiological impacts of fasting on our health and longevity. The other being people who want to profit from it. Intermittent fasting as a “diet” has been touted as a cure-all for everything from weight loss, to type 2 diabetes, even cancer. According to some of these folks, with intermittent fasting we can live longer and free from disease. All we have to do is start skipping breakfast.

What about intermittent fasting for athletes?

Athletes tend to be individuals who prioritize good health, so the promises that IF makes can be very appealing. Who doesn’t want to reverse aging, prevent cancer, and live longer? even outside the realm of improved athletic performance the benefits sound enticing.

What’s really going on while we’re fasting?

When it comes to intermittent fasting, there’s really two different potential mechanisms at play. The first is that people can lose weight while intermittent fasting because they’re creating a calorie deficit. What this means is they’ve reduced the total calories they’re eating by skipping one or more of their meals. This creates a calorie deficit which results in weight loss. From that we can see improvements in health markers like blood pressure, diabetes control, or heart disease. Some people find IF to be an easier calorie reduction strategy than trying to stick to other diets. In theory these would provide the same results so long as the same calorie deficit was maintained on each diet.

Nutrition research strongly supports this idea – weight loss comes from a simple reduction in calorie intake. There’s nothing magic about it. What may vary from person to person is the strategy they personally find the easiest to stick with long-term, which is what will produce the results they’re looking for. The human body is complex, and things like hormones, metabolic rate, hunger, and satiety are all a part of this system. At the end of the day though weight loss does require a change in this total energy balance.

Intermittent Fasting and Autophagy

Now the other aspect of intermittent fasting that is gaining major traction is something called ‘autophagy’. This is the thing that has longevity researchers, biohackers, and health-minded folks absolutely enamored. It also is more of a draw for many athletes than the potential weight impacts. Autophagy is a process that takes in place within our body’s cell where dysfunctional, damaged, or unnecessary cell components are recycled or removed as waste. You can see why this would spark all kinds of ideas about reversing aging or preventing different types of cancers.

Autophagy though is a delicate balance like everything in the body. We definitely want these processes to occur, but too much or too little can be harmful to our health. More autophagy is not always better! At this point from a research perspective there are more questions than answers about autophagy, and research in athletes specifically is even more sparse.

When it comes to IF and athletes studies really tend to focus on things like body composition changes. They often don’t explore IF’s impacts in the context of a larger picture of athletic performance which includes far more than just an athlete’s weight or body fat percentage.

So sure, incorporating IF into your nutrition strategy may lead to weight loss (like I described above), but depending on your sport a lower body weight doesn’t necessarily translate into better performance.

Autophagy and IF for Athletic Performance?

With that, fasting has come front and centre as something we can do that promotes and speeds up the autophagy process. The challenge with really breaking down IF for athletes is that there’s a number of different types of fasting out there. Also, each individual athlete has different training schedules and energy needs.

For example we have two methods of “time restricted eating”, one called “early TRF”, and one called “late TRF”. In early TRF we eat all of our calories earlier in the day, and fast through the evening and overnight. With late TRF we fast overnight and into the mornings, eating all of our calories later in the day. This is a vastly different strategy than other forms of fasting which promote a smaller eating window. Some limit eating to only 4 hours, or require entire days of no food intake. Comparing the outcomes of different studies or personal experiences which utilize different fasting methods is truly comparing apples to oranges. 

What else can athletes do to enhance autophagy?

Interestingly, sleep and exercise can also promote autophagy to some extent. Which begs the question; Is there any benefit to IF beyond what we might get from regular active and consistently getting adequate rest?

Some athletes have found that intermittent fasting seems to do wonders for their health and performance. When we take a closer look it may be that they’ve reduced their body fat percentage and with that improved their speed/agility. Or perhaps they now have better sleep quality from not eating a lot late in the evening. Some may even have fewer digestive complaints while on the track because they’re saving their large breakfast for after practice. Whatever the case if you’re unhappy with any aspect of your eating or performance there is definitely a benefit to taking a close look at the timing and composition of your meals. It’s important to make sure that meal timing jives with your training schedule. Unfortunately, picking an IF strategy that isn’t based on your personal needs is unlikely to pay off.

Will intermittent fasting make you a better athlete?

So, could intermittent fasting unlock your athletic performance potential? At this point, it doesn’t look particularly promising if it requires a disconnect between meal timing and training. It may be a worthwhile fat loss strategy to help some athletes continue to adequately fuel around their training schedule. But, it’s important to maintain other performance enhancing practices, like getting enough calories to support training, and prioritizing rest and recovery. As an athlete if you’re trying to train while under-fueled, aren’t hitting your protein target for recovery, or are skipping out on sleep due to the timing of your eating window, IF is actually likely to impair performance, not enhance it.

On the flip side if your goal is a reduction in body fat, but you still want to train and perform your best, timing your calorie intake around the time you’re most active is actually a logical strategy. Fueling up before exercise, having a solid post-recovery meal, then limiting calories for the remainder of the day might be a better idea than trying to achieve the same result with an overall huge calorie deficit. The important thing to remember though, is that the fasting itself isn’t what’s enhancing performance. It’s the side effects of choosing it as your strategy.

The bottom line

Whatever you choose, be sure you’re still achieving your calorie goal, getting enough protein, and timing meals around your training schedule.  If you’re not able to eat enough in your feeding window to meet your nutrient targets, or aren’t seeing any performance benefit from a trial of IF, then it just isn’t for you. Remember, all of us do intermittent fasting to some extent overnight while we sleep anyway, so if you’re getting in a solid 8 hours of rest each night, you’re probably doing just fine regardless!

Curious about other popular nutrition trends and their impact on athletic performance?


About the Author: Stephanie Hnatiuk is a Registered Dietitian and Personal Trainer who specializes in helping athletes reach their peak potential with nutrition.

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