I hardly drink any fluid during the day; maybe a glass of water with my evening meal. I've been like this my whole life - I just don't get thirsty. Someone told me that this is dangerous. What do you think? I don't handle warm temperatures very well. Could it be related? -- The Lizard

Your body absorbs water not only through liquids that you ingest daily, but also extracts it from foods that you eat, as many fruits and vegetables are more than 80% water. Additional water is also produced as a by-product of the metabolic process. If you do not drink enough water, and your total body water falls by 1%-2%, your thirst mechanism is automatically activated. Only in certain situations is your thirst signal unreliable, such as when you are ill or exercising vigorously. In these situations, you need to be more aware of replenishing your body with fluids. This is also very true in warm climates where water loss through perspiration can be significant, so rehydration should be undertaken regularly.

Limited fluid intake results in fluid conservation. This forces the kidneys to conserve water, the results of which manifest in reduced urine flow, or more concentrated urine. If a person actually loses up to a 4% loss of body weight in fluids, then their muscles can lose their strength and endurance. This may be the danger that some of your friends have been talking about.

Some individuals actually do not have an active thirst mechanism. This is a result of not having responded to the thirst mechanism when they were young, and therefore their body has stopped sending this signal. Sounds like it couldn't hurt to be conscious about drinking more than one glass of water or other non-caffeinated beverage each day.