Dehydration occurs when the body loses 1.5% or more of its water content and can be caused by exercise, stress, diabetes, menstrual cycles, and low-carb diets. Mild symptoms of dehydration include bad breath, sugar cravings, feeling cold, fatigue, and irritability. More severe dehydration can lead to impaired driving ability, muscle cramps, headaches, constipation, and in severe cases, delirium and unconsciousness. Staying hydrated is important for normal bodily functions and overall health.