What are your experiences and thoughts on carbohydrate loading before a marathon? When would you recommend that I start reducing intake, and when should I start loading? How much should I reduce by? Should I eat more calories than usual when loading or the same?

Any clues or answers would be great!

I'd like to add another question:

Is it important to look at the glycemic index (GI) for the carbs I'm taking on during the carb loading? Does it matter whether the GI is high or low?

I've been looking around quite a bit and it seems some argue that it doesn't matter, while others argue that you should eat low GI food. Few of the people claiming to know whether to eat high or low GI carbs actually bother backing up their positions with any facts. It is usually along the lines; "it is important to choose low GI carbs", full stop. No explanation given.

I'm aware that higher GI foods cause a quick rise in blood sugar followed by a fast drop in blood sugar, but that alone can't really be the reason for going for low GI, can it?

So if you have any comments on this, please also provide an explanation (and maybe a link to some useful reference) to why, because I'm getting rather confused.

I like to take carbs half an hour before any vigorous exercise. Carbs need time to be digested and absorbed. If not you will probably get a stomachache when you start running.

Carbohydrate sources that are slow to break down provide a steady, prolonged release of energy, plus help you avoid the shits.

I won't comment on carb-loading in the days leading up, because there are many approaches, strategies, and myths, and I don't require it. However, before the race or training, for any endurance activity, you should avoid carbs within 90 minutes - 2 hours. This is because carbs shortly before activity encourages your muscles to use glycogen as a primary fuel source, which is what you don't want to do for endurance exercise. You will always use some carbohydrate, but that supply is very limited, whereas the fat supply is almost endless. Train yourself to use fat as a primary fuel source and you will develop substantial endurance, at which point you won't have to worry about carb-loading at all. You will be able to conserve your limited supply of carbohydrates for any race.

There are various studies available which indicate that there is little difference between High GI and Low GI prior to performance, yet post performance and exercise stores of glycogen seem to be replenished quicker with high GI intake. As for carbo-loading it is better to taper prior to the event than too carbo-fast. It is better to manipulate the training programme than to swap and change the diet. In respect to the nutritional arrangements some people believe that messing around with their diet will give them "the magic bullet" for improved performance. In reality training smart and appropriately and being prepared is the key. As for "Hitting the wall" this is more associated with dehydration than glycogen depletion.

man im becoming a nutritionist of something...

from what ive learn at uni, 3 days is sufficient to increase your muscle carb stores. That means u will have more carbs available to you during a race. When you run a long distance race, then you will be mostly running on fats. The carbs are used at the beginning, as well as sprints during a race, and at the end. Therefore, you want more carbs!!!!

load 3 days before on high GI carbs, and the day b4 add low GI. This will firstly increase your muscle glycogen stores as well as giving you a longer release of glucose during the race.

The most important part is hydration: before, during and after. Make sure that you are constantly intaking water as well as sports drinks (glucose and water) so that you are properly hydrated.

but i cant tell you how much to intake each day cos i dont have the studies in front of me... sorry!