Millions of us don't feel as good as we should because we don't drink the eight or more glasses of water we need daily. Water is an often overlooked nutrient, one that's involved in practically every bodily process.

I know that if I'm dehydrated, I feel really tired. But when I drink water regularly, I have more energy. That's because water assists in the loading and storage of energy-giving glycogen in the muscles. It's also a solvent and carrier for nutrients. It helps in digestion, circulation, and joint lubrication and even helps decrease the risk of some cancers. It also flushes toxins and metabolic wastes from your system. The more toxins and wastes in your body, the less capable it is of burning fat and losing weight.

There's a guy I've known for a long time who is 6 feet 3 inches tall, big-boned, and age 50-plus. He's also the most overweight person I've ever met. He once weighed around 210, but now he tips the scale at 500 pounds. He also has hyperinsulinemia -- meaning he has high levels of insulin in his blood -- which makes him prone to heart disease and diabetes and keeps him heavy, since insulin is a fat-storage hormone. His diet basically consists of meat and potatoes and diet soda by the gallon, and he gets no exercise. But in all the years I've known him, he has refused to drink water. Once I asked him why. It turns out that he hates the taste of plain water, and he says he'd have to be "desperate" to drink it.

Since metabolism is a chemical process requiring adequate water, and he doesn't drink it, every system in his body has become sluggish. He has no energy. His thinking is muddled. His body can't burn fat effectively. While it's true that many factors figure into these problems, his refusal to drink water is certainly a bad influence on his metabolism.

Keeping your body well hydrated is important for preventing dizziness, cramps, and exhaustion during exercise, too. It's generally a good idea to drink 1 to 2 cups of water 2 hours before you exercise, then drink more during your workout. When I work out, I drink a few ounces of water for every 10 minutes that I exercise. After your workout, you should replace the water you've lost through perspiration -- about 2 cups of water for each pound of lost body weight. If you can make the commitment to start drinking more water, you'll definitely notice a change in the way you feel and in your energy, and you'll feel the mental kick that sufficient water gives.

Try this with me: In the morning, instead of your usual cup of coffee or tea or can of cola, drink a glass of cold water. Supposedly, drinking cold water gives a little boost to your metabolism since your body burns calories to warm up the water. Then take a minute to notice how rejuvenated you feel.

I prefer to drink bottled water, mainly because it's easy to take with me, and I really don't like the taste of tap water. Bottled water fits my needs and my lifestyle. I am very picky when it comes to water; let's just say I'm spoiled.

There are different types of bottled water, so it helps to read labels. Spring water, for instance, comes from an underground formation from which water naturally flows to the Earth's surface. Purified water has been processed to remove minerals and contaminants; distilled water is one example. Some purified water is actually purified tap water, and the label must state that it comes from a municipal water supply.

Mineral water contains naturally occurring minerals and trace elements. In other words, these are in the water at its source and can't be added later. Sparkling bottled water, which I often enjoy with a meal, has a bit of a fizz caused by the carbon dioxide it contains. Artesian water is taken from an aboveground well that taps an aquifer, a water-bearing layer of rock or sand. Well water comes from a hole bored, drilled, or otherwise constructed in the ground to tap the water aquifer. All bottled water is strictly regulated at the federal level by the FDA and at the state level by state agencies.

Tap water can be contaminated with lead found in household plumbing materials, nitrate from fertilizers, disease-causing microbes that pass undetected through filtering systems, and other pollutants. In fact, I've read that there are 85 possible contaminants that can get into drinking water, according to the EPA. Fortunately, though, because of the federal Safe Drinking Water Act, municipal water systems serving 25 people or more are constantly tested for harmful substances. If there is a problem with your water supply, you'll be warned through the media or other outlets.