Dehydration means your body does not have as much water and fluids as it should. Dehydration can be caused by losing too much fluid, not drinking enough water or fluids, or both.
Don't forget to rehydrate with water or a sports drink after your run. You should drink 20 to 24 fl oz. of water for every pound lost. If your urine is dark yellow after your run, you need to keep rehydrating. It should be a light lemonade color.
Food for Runners
1. Focus on unprocessed foods.
to keep your fridge and pantry stocked with foods that make up a
nutritious, heart-healthy diet, such as whole grains, fish, lean meats,
vegetables and fruits. They'll provide essential nutrients, help fuel
your workouts properly and aid in your post-run recovery. Try to
minimize the amount of processed foods you eat.
2. Eat small meals
Throw the notion of three large meals a day out the window -- it doesn't work for runners. You need more calories during the day than sedentary people, so it's better to spread them out with a small meal every three to four hours. You'll find that eating mini meals will help maintain your energy levels throughout the day and keep you from feeling hungry all the time.
3. Don't deny yourself the foods you love.
We all know what happens if you don't give in to your favorite foods: One day you'll have a monster craving and end up overindulging. It's better if you allow yourself small portions of the foods you love and not force yourself to eat foods you really don't like. In the long run, it will save you calories, because you'll feel more satisfied and you'll be less likely to binge and eat mindlessly. Eating in moderation is the key.
4. Mix things up.
Try to not get into the habit of eating the same foods day after day. Pasta often becomes a staple of a runner's diet, but there are lots of other healthful and interesting carb choices for runners, such as couscous, rice or quinoa. Different fruits and vegetables supply different nutrients, so it's important that you eat a variety of fruits and vegetables too.
5. Don't forget about protein.
Runners focus so much on consuming their carbs that their protein needs sometimes get forgotten. Protein is used for some energy and to repair tissue damaged during training. Protein should make up about 15% of your daily intake. Runners, especially those training for long distances such as marathons, should consume .5 to .75 grams of protein per pound of body weight. Good sources of protein are fish, lean meat, poultry, beans, nuts, whole grains, egg whites, low-fat milk, low-fat cheese and some vegetables