Water is the recommended beverage on the Eating Alive Program. It’s one of the most important molecules in our bodies, making up more than half our weight.

Water is involved in all of your bodily functions including circulation, digestion, absorption of nutrients, removal of wastes and toxins, and maintenance of a constant body temperature. It’s involved in many of the chemical processes that take place in each of your cells and is the primary component of lymph, blood, urine, digestive juices, tears, and sweat.

Water helps to keep your joints lubricated and your skin healthy and it helps to prevent constipation. It can also make you feel full; often when we feel hungry even though we’ve eaten recently, our bodies just need water, not more food. In addition, water can make you feel more alert, give you energy, and may even help alleviate headaches—this is because your brain tissue is more than 80% water and requires a regular supply of it to function effectively. Lean muscle tissue is approximately 70% water so staying hydrated is important for any type of physical activity. So if you’re feeling tired or hungry, try drinking some water; you may be surprised at the positive effects you get.

Thirst is not always your best indicator of whether you need to drink water or not—often by the time you’re thirsty, you body is already dehydrated. And your sense of thirst diminishes as you get older.

The typical recommendation for the amount of water you should drink each day is about 8 glasses, but the amount you actually require will depend upon the temperature, humidity, your activity level, diet, and body size. When it’s hot outside and/or when you’re exercising, you’ll need to increase your intake of water. Your best guide is to go by the color of your urine; it should be clear or a light pale yellow. If it’s darker than that then you should drink more water. Those with certain health issues—such as edema, some heart conditions, high blood pressure, and kidney problems—may need to avoid excess water intake.

Rather than guzzling back a lot of water all at once—this may hamper proper absorption or assimilation of the water—sip it throughout the day to prevent dehydration. You may find it easier to remember to do this if you keep some water with you as much as possible during the day. It’s a good idea to drink a glass of water when you wake up in the morning because your body becomes dehydrated after so many hours without water.

Room temperature is best; cold water can weaken digestion and the body has to heat it up before it can be absorbed, thereby delaying hydration. Avoid drinking a lot of water (or any fluids for that matter) with your meals, because doing so may slow down digestion by diluting digestive enzymes and stomach acid which are necessary for proper digestion.

While it’s important to drink enough water, it’s possible to “overdose” on it. Drinking too much water can make the kidneys work harder and can dilute the electrolytes in your body, so remember not to overdo it.