You cannot survive without water. It is essential to replace water lost from regular body functions like sweating, breathing and urine production.  It is essential that these fluid losses are replaced to prevent dehydration. Water losses are higher in hot climates and when strenuous work or exercise causes the body to sweat more than normal. Keeping muscles tissues hydrated assists in exercise performance.   If you exercise you burn calories which is of benefit.  It is a good idea when exercising to drink during exercise to avoid dehydration after the exercise is over.

The brain recognizes when your body fluid is low through signals from your kidneys.  The brain signals a thirst reaction which prompts you to drink fluids.  Water is the ideal fluid for re-hydrating the body since it is calorie free.   Drinking alcohol in these instances is not recommended as it interferes with the brain /kidney communication and causes excess fluid secretion which leads to dehydration.  Therefore, when you are thirsty drink water and avoid drinking alcohol especially in hot climates in the middle of the day.

Drinking water for weight loss has no effect unless it is replacing calorie filled drinks with no calorie water. There are no significant benefits to drinking excessive amounts of water.  There are however benefits in eating foods higher in water content such as fruits and vegetables which are higher in fiber and take longer to digest.  Drinking large amounts of water alone does not promote weight loss.  Drinking a glass of water can suppress appetite. Drinking water before a meal fills the stomach and reduces the effect of ghrelin, however if drinking too much water it helps empty the stomach faster resulting in you wanting to eat the next meal sooner. The volume of water drunk before meals should be limited to a cup full for the best effect.

Body hydration signals:

The kidneys react through production of urine once your body is adequately hydrated, so if you are drinking lots of water and subsequently going to the bathroom a lot your body is indicating that you are fully hydrated, and you do not need to keep drinking more water. Your urine will be concentrated, dark in color and have strong odor if you are not drinking enough water.

Adequate hydration is also important for your gastrointestinal tract to prevent constipation. When you do not have enough water, the colon pulls water from the stool.

Drink water whenever you feel thirsty, you do not need to drink excessive amounts of water unless you are exercising to extremes.  Listen to your body signals and enjoy life.

Homework:

Use a water bottle when exercising including walking.

Eliminate sweetened drinks, only drink water to save unnecessary calories