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The principle of loading up on carbohydrates the night before a marathon is a good one in theory, but it's important not to get carried away. I recommend having a high-carbohydrate meal, such as pasta or pizza (I usually have pizza) the night before your weekly long training runs. A high-carb dinner will stay with you through the run the next morning. If you do your long runs in the afternoon or evening, have a high-carb snack, such as a bagel or leftover pizza (if there is any) a few hours before you run.
Experiment with different foods now and then, or see how you feel if you go out to dinner the night before a long training run and have something unusual. If you know what makes you feel energized but not bloated or sluggish because you've eaten it before your long runs, you can eat that same thing, or something similar, the night before the marathon.
During the week prior to the marathon, eat as you normally do. It's not really necessary to load up on pasta 3 days before the marathon, because it will be out of your system. Also, since you will be running much less than usual during the last week before the race, eating as usual will create some carbo-loading by default because you aren't burning as many carbohydrates by running.