Severe dehydration can cause symptoms such as extreme thirst, lack of sweating, rapid heartbeat and delirium, and it can be life threatening. But most people who experience dehydration experience mild to moderate dehydration.
Here are the effects of dehydration at a mild to moderate level:
- Fatigue
- Muscle weakness
- Poor concentration
- Headaches
- Dizziness or lightheadedness
- Decreased metabolism
http://www.functional-fitness-facts.com/effects-of-dehydration.html