can you train to run on empty?
wondering to get your thoughts on completing our workout sessions without nutrition... what i mean.... I find that often with shorter sessions, and especially running that I often in the past haven't had any specific nutritional intake during these sessions (including calories or hydration).. just wondering if there is any utility in this? can you "train" your body to kinda run on empty? I would do this on runs up to ~100 minutes (keep in mind this is happening in perfect 60 degree weather with a sea breeze...) really done for convenience of not having to carry stuff or get a running belt with water bottles etc..... basically laziness .. but made me wonder if there might be some benefit to this? I've had issues with hydration/nutrition before but never seem to have problems on shorter sessions??
any thoughts appreciated..
Comments
@Naftali Presser You will get some VERY different answers on this. The Core diet squad (there are MANY MANY of these people inside of EN who are very successful way faster than me) ascribes to the "fuel every workout" camp.
But since I am the first to respond, I'll give you the "Fat Adapted" perspective. In my world the answer to your question is absolutely yes.
I do almost ALL of my weekday workouts in the morning Fasted with nothing but water (if that). If it's super hot or longer than ~90 mins I will usually take water with me. But I have done up to ~3.0 hour workouts completely fasted and feel great. If you are eating a higher fat, lower carb diet this will be easier. It's also something you can "train" as often the reason you take a gel or sugar drink during/before a workout is that you "think" you need it. And some of the "bonk" people feel is mental and some is because many people are very efficient at burning blood sugar during exercise, but if that runs out they either need to top it off (with a gu or Gatorade) or they have a "crash". So in some ways if you are only trained to burn blood sugar, then maybe you actually do need to stay on the sugar drip. But our bodies have ~90-180 mins worth of Glycogen stores to start with (assuming you are properly eating a normal diet) that we can use as a primary fuel for most workouts. The better we train our bodies to be at burning fat, the longer we can go (and at higher intensities) without taking in external fuel. One of my ultra buddies has run for ~8 full hours on nearly no external fuel and NEVER even came close to a bonk.
So I believe (others might disagree) that training our bodies to burn fat during exercise (even high intensity) is one more tool in our efficiency toolbox. And if it's anything lower than 90 mins, we don't even really need fat burning since it will all come from your Glycogen stores (intra-cellular and from your liver).
Keep in mind that I always fuel after workouts (not with Carbs like some people). As that is what is needed to help top off your Glycogen stores for your "next" day's workout. If you will be doing multiple workouts per day, then there is also pretty good reason to fuel during your first workout.
With all of the above said, when I got into the meat of my IM training this yr, I added in a lot more carbs to my normal diet and also started fueling some workouts (including long runs and long bikes and even some of my higher intensity shorter stuff). Part of this was to squeeze every drop of performance out of my workouts, but a bigger part of this fueling was to train my gut and body to absorb fuel during workouts. I also felt like I needed something extra when I was doing say back-to-back Zwift races that were long and super high intensity.
Even as a bigger guy, 6'1" and 210+ lbs, I can ride and run on very little calories. I don't know why that is, due to my usually-consistent training with lower calories or having an efficient body. I'm betting it's on the former and not the latter. Even when I'm not in great shape I can do this (more fat stores, maybe?).
In my runs up to 2 hours, in much higher temps and humidity here in Dallas that isn't anywhere near "perfect", I only usually eat one HS waffle before and have no gels or anything else during the run except Nuun or water). During my 50k trail run a few years ago, I only had 3 waffles and a couple of maple syrup gels.
For my long rides, I eat about 600 cals before it (the composition of that depends on whether I am at home or not) and seldom have more than a few HS waffles during.
I know there's been a lot of discussion lately, in endurance sports and in general, about fasting and working out. Maybe our resident Nutritionist, @Sheila Leard can comment.
@Naftali Presser
Your intuitive sense that running without calories feels OK is correct .... up to a point.
Running at a comfortable pace is hopefully being fueled by intramuscular fat and glycogen. The degree of how much fuel come's from fat depends on daily diet. For example a vegetarian diet will typically have more carbs. That's not a bad thing because the added fiber and healthy fats can regulate blood sugar which will ultimately allow your body to oxidize fat more efficiently.
Once you start getting over 90 minutes of exercise taking in a small amount of fuel can be beneficial for keeping Cortisol down. This is the stress hormone that responds to carbs during exercise.
You really don't need many calories during low intensity exercise. Hydration trumps calories in these sessions. The research on no calories at high intensity sessions is pointing towards take in Carbs. ATP (energy) can be made more efficiently with glucose than fats. I don't see a performance benefit in not fueling interval work.
The confusion that is out there is that there is no definition of what high carb is, especially for athletes. If you are having gut issues with fueling longer sessions start focusing on daily diet, having a healthy gut and stay hydrated.
Both @John Withrow and @Scott Alexander are examples that training on less can work. Experiment in training on how much to take in. You might be surprised at how little you need.
I am not a member of any of the religious sects when it comes to nutrition. So I let the circumstances of the workout determine what I drink or eat. I have learned that I can make it through any given workout or race of up to 2 hours +/- with little fluid and no fuel. I don't do that as a matter of routine, but sometimes it happens. Other times, especially during longer IM training rides/runs, I make it a point to mimic what I plan n doing race day - drinking every 10-20 minutes, getting 300 calories +/- every hour. What I've learned from all this over the years is that going without comes with a cost, not during the current workout, but in the subsequent one(s). Depending on how hard and/or long the workout is, and how much you have followed Withrow's protocol, you will eventually start to tap liver and muscle glycogen stores. If those are not fully topped off either during the workout or within two hours afterwards, you will underperform the next time out, or even the next few times. And that will affect the quality of your training overall when it comes to progressively building up fitness.