I was recently asked my thoughts on carb-depletion/carb-loading, and how it affects marathon performance. There’s quite a bit of data to suggest that carb-depletion and subsequent loading does work. However, results are individual and many people do not fare well mentally with true depletion/loading. It’s also not recommended if you aren’t already tracking your macronutrients and/or if you plan on fueling during the race itself since you won’t really be truly depleting your reserves during the race anyway. Having said that, let’s get into what it is and how (and why) it works.
Disclaimer: this post is a very, very brief overview and synopsis of carb depletion and loading. This is a very in-depth subject area that a lot of writers, scientists, runners, and doctors have researched and published information about. Please do some additional research if this topic interests you. Likewise, I’m not a scientist or doctor. I’m a running coach and a runner and this post reflects as such.
Carb Depletion and Loading
Carb depletion/loading is a method to deplete your muscles of all glycogen stores and then stock them full to the brim prior to an endurance event. The theory goes that when muscles are depleted of glycogen (the energy from carbohydrates), they will be able to store more glycogen once carbohydrates are reintroduced into the diet. Effective carb depletion takes about four days with roughly 10% carb intake of the total diet. The remaining 90% of the diet is made up of fats and proteins. The carb loading phase takes effect in the three days leading up to the race, with the reverse macro-intake. In the loading phase, 90% of calories consumed should be carbohydrates, with the remaining 10% fats and proteins.
Carb Depletion and Training
During carb depletion and loading, your training does not change. The volume may, but the workouts themselves will not. You will be running some tough workouts in a glycogen depleted state, which often times makes the workout feel harder than it would be under normal circumstances. You may feel sluggish, your legs and feet like lead, and overall very lethargic. If this is the case, you’re doing it right.
Carb Loading Phase
When you’re in the loading phase, you don’t want to pile on the carb calories. This is a pitfall many runners have fallen into with sometimes less-than-ideal effects come race day. If you overload your body with extra calories and too many carbs, you’ll end up feeling bloated, uncomfortable, and could end up with GI troubles.
The fat-adapted state is a fantastic option. Our fat stores are almost unlimited. Unfortunately glycogen is a much easier source of energy for our bodies but it’s finite and runs out after some time. The dreaded “wall” or “bonk” occurs when your body burns through all the stored glycogen and begins burning fat. Fat takes too long to burn adequately — hence the slow down. Avoiding the bonk is one reason we often hear “fuel early, fuel often” — you don’t want to get to the dreaded moment when you run out of glycogen and have to rely on fat only.
But — there’s hope yet. If you run in a fasted state (no breakfast, no fuel on the run, no nothing), you can effectively train your body to burn fat as fuel. The fat-adapted state is an entirely different post for another day, but we’ll revisit it next week. It’s definitely something to consider if done properly.
Takeaways to Consider
What are the takeaways here? A few:
1. If you’re not willing to suffer through some grueling workouts, mood swings, and hanger (hungry anger) in general, true carb depletion and loading are not for you.
2. If you’re planning on using gels, sports drinks, etc (and you should!) on race day, depletion/loading are likely not necessary for you.
3. Carb loading does not mean to pile on the carbs. It means to switch the ratio of carbs to proteins and fats so that the percentage of carbohydrates is higher — not that you’re adding more calories overall.
4. Most of all, don’t try anything new on race day. Marathon training is your dress rehearsal for race day. If you’ve been eating a certain way or fueling a certain way, continue to do so for your race.
5. Fat adapted training is a great option for those interested in using fat as fuel. Look for a post on that topic next week.
6. This is truly just the tip of the iceberg when it comes to marathon nutrition. Do your due diligence and research the heck out of this topic if you’re considering going the depletion/loading route.
And now for the Running Coaches’ Corner! Join Lora Marie, Susie, Debbie, and myself for the Running Coaches’ Corner linkup every Wednesday. We love reading your running stories, racing tips, and coaching strategies. Scroll to the bottom of this post to add your link!
TALK TO ME!
Do you practice carb depletion/loading?
Do you experience mood swings during the depletion phase?