The Feed | Fasted Training

This piece touches on the practical application of Fasted Training (FT), its downfalls, and the potential performance-enhancing  benefits. It's not a "how-to" guide, but rather a briefing for making your own decisions!

What is Fasted Training(FT)?
Firstly, “fasting” is simply a period of retention or abstinence from eating. In a physiological context, fasting might be the metabolic status of someone who has not eaten for a prolonged period or overnight. In most research scenarios, fasted exercise is performed the morning before the first meal of the day and the individual(s) have not eaten for eight to twelve hours. Thus, Fasted Training (FT) is exercising or training in that state, where glycogen stores are depleted and glucose is not readily available.

Typically, fasting is a lifestyle management protocol that can benefit several disease-related states and help to improve metabolic health. Yet, it’s become a hot topic in the endurance and performance world over the past decade. Why?

The Big Question:
Does Fasted Training (FT) improve overall endurance performance?

The common theory is that if you train in a fasted state, you will train your body to utilize fat as a fuel source and spare glycogen, therefore improving endurance performance. The answer is not so cut and dry, though.

Considerations:
What we do know is that fueling with carbohydrates can have huge performance benefits to athletes. That is proven and truly emphasized by the recent trend in high-carb fueling protocols by elite athletes and teams. You might ask, then, why would we want to limit carbohydrate availability if it improves performance?

Well, we know pros do have an increased reliance on fat metabolism. Endurance athletes can benefit from being metabolically flexible, meaning they have the ability to adapt to the demands placed on their bodies and utilize both substrates as fuel. That means you can respond to a variety of efforts with the most efficient fuel source. Imagine your body as a dimmer switch and not an “on/off” switch – we want to be able to burn the right fuel at the right time.

Even if you become a fat-burning machine, you will never be able to tap into fat energy stores as efficiently as your bodies ability to convert glycogen to energy. You want (need) both.

Can I just do a high-fat diet?
It’s been shown that a high-fat diet in conjunction with endurance training stimulates the ability to use fat, but “fails to enhance endurance performance because the ability of muscles to use muscle glycogen (carbs) is impaired”. (source)

In lemans terms, eating high-fat turns the dial down on how well your can use carbs for fuel. That means we can become less effective at doing high-intensity efforts because we can’t appropriately fuel them.

However, as a nod to FT vs high-fat diets, FT seems to promote fat oxidation, while maintaining the ability to break down glycogen. What’s that mean? It suggests that training in the fasted state may benefit endurance performance by promoting the use of fat as fuel while maintaining the ability to produce energy via glycogenolysis (or the breakdown of glucose).

Simply put: the ability to improve fat as a fuel source may not necessarily translate into improved endurance performance. (source)

Potential Benefits of FT:
1. Improved fat oxidation.
This means taking the fat stored in your body and breaking it down into fuel. It requires ample oxygen and takes more time…but is a more efficient and robust energy source. Thus, it’s the preferred source at low, aerobic intensities. This effect, however, specifically comes from spending time in that aerobic area (easy).

2. Glycogen sparing.
With more reliance on fat as a fuel source, you spare (or save) carbs stored in your muscles for longer. This is desired because it means that it takes longer and/or harder efforts to tap into those rich carbs, which are like nitro when we need it. Think: a finishing straight sprint.

3. Enhanced autophagy.
This area is a little grey, but exercising in a fasted state may increase the role of autophagy (the recycling and cleaning of your cells). This happens naturally when you are in states of fasting but may factor in more effectively when you’re active following a fast as well.

Negatives of FT:
1. Reduction in “ceiling”
Less fuel = less gas in the tank. If you don’t “feed” your body or train without bringing on fuel, you will have less potential to really move the needle. So, if you have a goal for your workout that involves intensity, you’re not going to have the fuel on board needed to improve that workout.

2. Not beneficial to muscle mass
It’s been shown that FT can negatively impact muscle mass/growth. Something called proteolysis, or the breakdown of protein in your muscles, can accelerate when training in a fasted state. Depending on your goals and training routine, a little FT may not reduce your muscle mass, but routinely exercising like this won’t help if you are hoping to gain muscle overall. (source)

3. It’s Additional Stress
When it comes to how your body handles things, stress is stress. If you are stacking FT on top of a heavy training routine or high volume, then be aware that you’re adding another stressor. Training without fuel available requires your body to break things down to get it –that’s stress. This may make workouts unproductive, lead to worse recovery, and an overall decline in performance.

We know that whether it be an energy-sucking work call, a negative life experience, or a hard training session, the body will react at a physical level.

How to manage Fasted Training (FT):
Keep up on electrolytes. With a lower amount of carbohydrates on board, which improve fluid retention and hydration. LMNT can be a surefire way to improve hydration while in a fasted state – their product is “fasting-friendly” with no added sugars. New research suggests many people –especially athletes and those following paleo, keto, or low-carb diets– are actually under-salted. Plain H2O just won’t cut it.

Add a protein bump. Adding a whey or basic protein supplement to your morning coffee can be great for striking that balance between training “low” and improving the quality of your session. We love to make a coffee before heading to the gym or out on a ride while tossing in some protein to get that protein bump. You can also add it to a Kyoku or Gnarly Greens shake to incorporate some highly bioavailable micronutrients!

Fuel the work. FT can be incorporated when the exercise is done in a low and easy state. If you don’t have anything taxing on the schedule, then a light FT session shouldn’t harm you. Otherwise, fuel the demands at hand. If you have a workout on tap, it’s best to come into it fueled up to get the most from that session.

Should you train Fasted?
Let’s start by asking one question. What are your goals for training: performance or general health?

This sets the framework for whether or not FT is necessary and how much it should be implemented. Training in a fasted state can be a helpful addition to your routine if the activity level is low and the duration is short. For example, a morning walk, yoga session, or short ride before work may improve the breakdown of fat. As the intensity or duration climbs, so should your fueling.

If you’re seeking performance improvements, your best bet is to train with ample fuel for the fire. As LMNT suggests, training “fed” gives you more energy potential, prevents muscle breakdown, and reduces your overall stress burden. This leads to improvement and growth over time.

Sources:

        Services, G. F. (n.d.). Does cardio after an overnight fast maximize fat loss? : Strength & Conditioning Journal. LWW. Retrieved November 1, 2022, from https://journals.lww.com/nsca- scj/Fulltext/2011/02000/Does_Cardio_After_an_Overnight_Fast_Maximize_Fat.3
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    Vandenbogaerde, T. J., & Hopkins, W. G. (2011). Effects of acute carbohydrate supplementation on endurance performance. Sports Medicine, 41(9), 773–792. https://doi.org/10.2165/11590520-000000000-00000

         Van Proeyen, K., Szlufcik, K., Nielens, H., Ramaekers, M., & Hespel, P. (2011). Beneficial metabolic adaptations due to endurance exercise training in the fasted state. Journal of Applied Physiology, 110(1), 236–245. https://doi.org/10.1152/japplphysiol.00907.2010

         Villaseñor, L. (n.d.). Should you train fasted? benefits, downsides, and when to do it. Drink LMNT, INC. Retrieved November 3, 2022, from https://drinklmnt.com/blogs/health/should-you-train- fasted-benefits-downsides-and-when-to-do-it

        Zouhal H, Saeidi A, Salhi A, Li H, Essop MF, Laher I, Rhibi F, Amani-Shalamzari S, Ben Abderrahman A. Exercise Training and Fasting: Current Insights. Open Access J Sports Med., 11:1-28. doi: 10.2147/OAJSM.S224919. PMID: 32021500; PMCID: PMC6983467.Services, G. F. (n.d.). Does cardio after an overnight fast maximize fat loss? : Strength & Conditioning Journal. LWW. Retrieved November 1, 2022, from https://journals.lww.com/nsca- scj/Fulltext/2011/02000/Does_Cardio_After_an_Overnight_Fast_Maximize_Fat.3
​
    Vandenbogaerde, T. J., & Hopkins, W. G. (2011). Effects of acute carbohydrate supplementation on endurance performance. Sports Medicine, 41(9), 773–792. https://doi.org/10.2165/11590520-000000000-00000

         Van Proeyen, K., Szlufcik, K., Nielens, H., Ramaekers, M., & Hespel, P. (2011). Beneficial metabolic adaptations due to endurance exercise training in the fasted state. Journal of Applied Physiology, 110(1), 236–245. https://doi.org/10.1152/japplphysiol.00907.2010
Villaseñor, L. (n.d.). Should you train fasted? benefits, downsides, and when to do it. Drink LMNT, INC. Retrieved November 3, 2022, from https://drinklmnt.com/blogs/health/should-you-train- fasted-benefits-downsides-and-when-to-do-it

        Zouhal H, Saeidi A, Salhi A, Li H, Essop MF, Laher I, Rhibi F, Amani-Shalamzari S, Ben Abderrahman A. Exercise Training and Fasting: Current Insights. Open Access J Sports Med., 11:1-28. doi: 10.2147/OAJSM.S224919. PMID: 32021500; PMCID: PMC6983467.