Changes

If you weigh yourself before and after you run the difference between the two numbers will be the change in body water. However, on a longer run (~16+ miles), you will lose about 4 pounds due to burning off carbohydrate (glycogen[[Glycogen]]). So if your weight has dropped 0-4 Lb, you're probably hydrating okay. If your weight has dropped much more than 4lb, you may need more fluids and possibly electrolytes. If your weight has gone up, you probably need more electrolytes.