Morning Run: fasted or fueled?

Long run for me this morning, 14 miles- started at 7.

Had a granola bar and glass of OJ before starting then a gu and a bottle of water half way through. This is pretty typical for long run days.

I am mostly a morning runner during the week for 4-8 miles at around 5AM and almost always do them fasted and with no nutrition until the end.

I no longer eat before or during a morning run, even long runs over 20 miles. The reason for the change was simply stomach upset, which I get quite badly if anything is in my stomach. But the change allowed me to finally stop bonking on long runs. I can now easily run 20 miles without fuel, even if there is a workout in the long run, whereas before I adapted to running on an empty stomach I would routinely hit the wall in training. Now I'm a fasted-run convert (and yes, I mostly train for marathons; when I am not, I still run on an empty stomach, but it's a moot point because my long runs are short enough that fuel wouldn't be needed, anyway).

I do have coffee with milk as soon as I wake up, so that's about 20 calories or so, and some water; during long runs, I take salt tablets in the summer. They are electrolytes only, and help me keep my blood pressure up when I'm pouring sweat in 90 degree heat without adding any glucose to my system.

Someone upthread mentioned that sports drink provided a temporary boost, but was later followed by feeling worse. That's due to insulin release. Your body is not perfect, and also can become a bit habitual. When you consume sugar, your body releases insulin in response, which works to store the sugar in your cells. However, this can create a problem when you're running: for one thing, the amount of insulin released may be out of proportion to the small amount of drink consumed, when your body anticipated a regular breakfast. But additionally, you're using the sugar to fuel your muscles as soon as you take it in, so you really don't need to store it all. Some is being immediately put to use. The result is that too much sugar is stored, including glucose already in your blood stream and glucose your body has just converted from stored glycogen - and you end up with less available fuel than before!

Your body can learn to adapt to your sports drink routine, of course, but then you are just teaching it to rely on exogenous sugars to fuel. If you run fasted, your only option for fuel is gluconeogenesis, in which the liver converts fats to sugars. This process is inefficient, so if you run fasted, you have to slowly increase distance to give your body time to adapt. The human body is pretty smart, so over time you will get better at gluconeogenesis, and that will allow you to run longer before you need additional fuel. This is important, because you will be burning more calories per hour in a race than you can take in. You can rely mainly on the stored glycogen in your muscles, but that's not enough - numbers vary depending on muscle mass, but it's about 1600 calories, not enough for a marathon. Even in the most readily-absorbable form, carbohydrates can only be utilized at an upper limit of about 120 calories per hour (and you can assume that you will be much less efficient than that on race day, when blood is diverted away from the GI tract to your working less muscles). If a marathon burns 2500 calories, and you get 1600 from glycogen and 400 from taking in food and gels, you're still short 500 calories. To make up the difference, you require gluconeogenesis, and to practice that? You run fasted.

Eat carbs the night before...that what the Military does before (weekly) 5mile runs... they say: CARB UP.

For Military runs, especially above 5miles... it was almost always a religion to carb. up the previous night/week before runs... as we rarely had time to eat anything before running at 5/6/7am anyway. If I totally fasted I would have died many times over (some actually did), so that was NOT an option or something safe to do. If possible, before the run, I would have drank a little gatorade and ate some wheat bread- but never too much, or I would have gotten sick-never ran on a full meal, ever. But, I don't see how any runner could fast long before a run ... eating carbs the night before SEEMED to work for me. When zero fuel could be had prior to runs, my body wasn't fully awake until after we completed the runs, so luckily I never had issues. However, I wasn't the healthiest/manliest specimen, so I'd be curios how an athelete of 20 years would answer your question- or a specialized doctor (MD/Nurse/Heath/Nutrition PRO, etc).

Interesting about the sugar drinks (like gatorade)- I wish I knew that in the service, but we were not pro runners- and all were clueless about health, as was probably all military trainers back then- sorry Airborne Rangers, but you were pretty clueless about health/nutrition, medical- unless maybe in combat situations or sims... Among other things, I have had a stomach hernia- earned through training- which was noted as a essentially no big deal in 1990, and thought as just another pulled muscle- not to worry! Can't even dream of running today...or do anything that involves stomach muscles since, so doubt they were the best to train us to run either.

why do people use words like "fuel" and "nutrition" when you can say the words "eat" and "food"?

"If you run fasted, your only option for fuel is gluconeogenesis ..."

Or you could just burn the fat instead of burning glucose.

I think gluconeogenesis makes glucose from protein rather than fat, but I'm not sure. It's pretty slow anyway, so I don't think it has much influence on running.

I agree with the general idea though, running fasted is the way to stop bonking, lose fat and be healthy.

It depends on the adaptation you want.

words wrote:

why do people use words like "fuel" and "nutrition" when you can say the words "eat" and "food"?

Because dbag cyclists and triathletes like to dork out.

Overnight you deplete your liver glycogen but if you ate the night before, your muscle glycogen is still pretty topped off so running fasted in the morning doesn't do that much for fat adaptation. If you really want to do the fat adaptation thing, you need to run the evening before and not eat carbs after and then run fasted in the morning.

It's something to play with, but not a magic hack or anything.

http://scienceofultra.libsyn.com/training-on-low-glycogen

We, Kenyans, run at 6am fasted. That's the true.

Experiment to see which one works better for you. It should not take you longer to figure out.

fatbrnr wrote:

"If you run fasted, your only option for fuel is gluconeogenesis ..."

Or you could just burn the fat instead of burning glucose.

I think gluconeogenesis makes glucose from protein rather than fat, but I'm not sure. It's pretty slow anyway, so I don't think it has much influence on running.

I agree with the general idea though, running fasted is the way to stop bonking, lose fat and be healthy.

Gluconeogenesis can occur from the glycerol part of the fatty acid molecule as well as from protein, but the rest of that fellow's post is really sloppy.

Fat adaptation as a strategy seems pretty overrated to me and in a study of racewalkers they actually got worse. See Louise Burke's paper from a couple of years ago.

Also, if one is going to try fat adaptation strategies I think it should be done only after people get the rest of their training dialed in. Same for altitude training. People want to reach for the things that might improve performance by a small percentage rather than do the things that offer the biggest return (training well and recovering well). Get the basics down and then try the sophisticated stuff.

In the summer I run early AM and eat afterwards. Not a problem for easy runs or easy paced long runs. I do my longer and/or faster long runs and big workouts on the weekend or the afternoon when I have eaten. I always have a glass of water when I wake up before I go however. Not a big caffeine guy so I can't speak to that.