Carbo Depletion/Loading


Experience From -
Steve Schuder , Blake Wood , Larry De Angelo , Paul Anderson , Christian Hottas#1 , Jeanie Baker , Karl King , Christian Hottas#2 , Matt Mahoney , Ray Krolewicz , Ivan Drvaric , Rod Hasker ,

Steve Schuder

I'm looking for feed back on something that I do about once a year prior to my "big" race for the year. For 2 1\2 days starting six days prior to the race I only eat protein (ie no carbos. or fat) This effectively depletes my carbo stores. Then for 3 days prior to the race I do the routine carbo. loading while still eating some protein and fat. I am an experiment on one, but in my mind I feel that I race well when I do this.


  1. Is this a good idea?
  2. Is it effective?
  3. Is it safe?

Blake Wood

I tried carbo-depletion/loading a few times before marathons when I was in college, with little discernible effect. However, I know many people swear by this for marathons.

For longer runs, however, I think it would have little effect. The idea behind this is to stretch your reserves enough that you can make it through the race on what you bring to the starting line in your muscles. A marathon is about at the limit for being able to do this. In longer runs, you have to rely on what you can get out of food you eat during the run. I'd guess this applies to 50 miles and up. I know that in hundred milers, I usually hit a low point after 6 hours or 30 miles, which I interpret as having depleted my muscle stores. After that, it's what I can eat that keeps me going.

Larry De Angelo

I have had some of my best ultra runs going the opposite of the conventional carbo-loading wisdom. When I have been on a continuously low-carb diet, I have run well without even loading. My guess as to what happens is that after a while of running without a lot of carbs around (several weeks+), the body gets used to burning fat which is what you want when the distances get long anyway. It seems to work well for me. Maybe some of the physiology wizards can explain?

Paul Anderson

This was the craze when I was doing serious marathon training in the late 70's. I haven't heard much about since, I figured it went the way of LSD and other early training ideas. Did it work? I did it prior to several races including my PR at NYC. I found it difficult to stick with (what meal in college has no carbs?) and it made me irritable and tired. I don't know if the benefits were more mental or physical, but it seemed to work for me. Has anyone tried this diet prior to an ultra?

Christian Hottas#1 (General medicine/sports medicine)

Steve, what you describe is well-known as "SALTIN-diet". Saltin who is from Finland developed this was of preparing for a marathon in the 70's for international top-marathoners. As far as I know it works. Jörg Peter, the (East-)German record holder (2:09 h in the 80's) used to use it. But the problem is that you feel very weak when you deplete your carbo stores. You must be very truthful to this method to follow its line. After having refilled your carbo stores you will have 1 or 2 kg more than before (which is water that you took in your muscles together with the carbos and which is fluid reserve for the race). Saltin diet shall be useful for marathon distance. But I don't expect that it works for ultramarathon because here it is not so important how big your carbo stores are because you will be much more in fat burning.

Jeanie Baker

Steve, If this process doesn't affect your performance or in your mind enhances it, no worries. I would not recommend trying programs like this in general and if first you are deleting your carbo stores and then building them again, what is the point? It doesn't make sense that your body can make those adjustments in just two or three days.

I am certainly no expert, but after asking every ultrarunner I know, other runners, nutritionists and an exercise physiologist about this very issue, I have been told:

  1. Do what works for you.
  2. Do not try anything new before a race.
  3. Most "depletion" programs are ineffective unless you are already on a VERY strictly monitored nutritional program, i.e. professional or Olympic athletes who are attempting to maximize their performance under the guidance of a professional nutritionist.
I think the comments that your carbo stores are pretty much gone by the end of marathon distance are correct in my case. I seem to do fine on eating extra for day 3 and 2 prior to long run, 25 or greater miles, then regular diet the day before, and even if I eat a LOT more on day 3 and 2, it doesn't seem to make any difference, about mile 25 I have to start eating like a pig or I run out of gas.

Karl King

This method has some benefit for marathons, but more recent research shows that the important part is the carbo loading phase, and the depletion phase is not that beneficial.

Anytime you load up heavily on just protein, you put a major strain on your kidneys. That doesn't make sense before an ultra.

Philosophically, I don't like this kind of program at all. I've worked for months to train my body for a big event. Why, in the last few days, should I put my body through some bizarre eating phase that I wouldn't otherwise consider as rational or enjoyable? Are we having fun or just being neurotic? Let's step back a minute. Unless you're world-class, the percentage of the earth's population who care what time you run is basically zero.

One very fast runner I know who ran sub 6:00 at Ice Age told me that he pounds a lot of liquid carbs the day before the race. Other than that, he does no special dietary manipulation.

Blake's point is valid: carbo loading for an ultra won't make much difference because in any ultra of consequence you'll run out of leg glycogen before the finish line. What's far more important is to go out comfortably. The most dangerous miles of any ultra are the first 4 because that's where a fast start will burn a lot of glycogen that you'd like to have later. Some fancy loading program will have been for naught if you blast off the line.

What seems more important is to find out what kind of pre-race meal gives you the best results. There are likely to be a lot of personal variation in that. Some people can plow down a huge amount of carbs before running and do ok. For me, that's a disaster. My best runs have come when breakfast had a healthy(?) dose of fat, and some coffee. That might come from an oily bran muffin, or from a sausage/egg/cheese biscuit.

In any case, explore and have fun.

Christian Hottas#2

Karl, You are totally right. It is more important to have fun with running than to fight for very unimportant seconds (if we are not world class or at least going for course records).

Matt Mahoney

I basically agree with what others have said about carbo depletion and loading. In theory it would help for marathons but not for shorter races (you will have enough carbos without loading) or longer (you will run out anyway). The idea of the depletion phase is to force your body to conserve glycogen so that during your loading phase you will store more than normal. A normal supply is 2000 calories worth of glycogen, enough for a 20 mile run if you burned strictly carbos and no fat. Ultrarunners tend to burn fat more efficiently, so you are not likely to run out after 26 miles even if you didn't carbo load. The weight gain (1-2 kg) is because each pound of glycogen (2000 calories) has to be diluted with 4 lbs. of water in your body. Carbo loading would probably make you slower for races shorter than a marathon. Fat is stored more efficiently, 3500 calories per pound with no water weight.

Anyway, that is theory, because I have never carbo-depleted and don't intend to try it. Before any race, whether 5K, marathon, or 100 miles, I eat my normal diet including a normal breakfast on race day.

For What It's Worth, here is what I ate during Hardrock (42 hours) and Nolans 14 (55 hours) this summer. For breakfast, mostly carbos (if possible, my usual raisin bran, milk, orange juice), for lunch, lots of protein (4 oz. turkey, 2 oz cheese, 2 slices of bread), afternoon carbos and fat (peanut M&Ms, potato chips), supper, whatever was available, more protein and fat, at night, mostly sugar and caffeine. My food intake was probably only half of what I would normally eat, because that was all I could get down. While training in the mountains for 2 weeks before each race, I would go on hikes of 6-12 hours and eat huge meals afterwards, and still lose 10 pounds by race day from about 163 to 153 (6 ft 0.5 in tall). One day for breakfast before a hike I had 2 bowls of cereal and 10 pieces of French toast with syrup plus milk and juice. After Nolan's I went to breakfast and had 3 full plates of food.

Ray Krolewicz

Blake, et al, I know you are smarter than I am and everything, but I would not dream of doing a serious (intending to run fast) ultramarathon without depleting and loading, of course I too am an experiment of one, but after a few trials, with and without this course of action my statistics bear doing so. I am sure I am wrong on this however, which just goes to show how insignificant experiments of one really are, so who is next up for a dissertation study?

Ivan Drvaric

I agree that fun is more important than catching results and first prizes. But in every effort you make has no sense if you're not observe yourself , how your body is react to the activity you make . And ultra-marathon is such activity that needs observing your body and soul even more . So why little theory and dissertation would be bad? It is always good to get some other view and try making yourself to understand something that someone has already found out but in some other way.

So I think both is important , not to exaggerate with theory and still to keep yourself in fun but still to get something interesting from this and to cooperate in the process of finding out new facts and...

Rod Hasker

The following was included in a Runners World Extra morning:

More fat = more endurance: According to a new study by the University of Buffalo, a low-fat diet may hamper your endurance. Researchers concluded that a medium or high caloric intake from fat, about 30 to 45 percent of your total caloric intake, is your best bet for improving performance if you run at least 35 miles a week. The reason that some runners simply need more calories. Also, when your body burns fat for energy, it conserves glycogen, which is always in relatively short supply.