You Stay Regular
It's common to get a little constipated if you don't drink enough water. Inactivity, diet changes, illness, and even stress can add to the problem. The constipation usually passes on its own, but you can help move things along with exercise, over-the-counter meds, and of course, water.
See a doctor if your constipation lasts for more than a week or two or you have dizziness, bad pain in your belly, or blood in your stool. These could be signs of something more serious.
Your Joints Work Better
Water makes up a large part of your joint cartilage that helps absorb shock and make bone-against-bone movements smoother. Water also can help keep gout (a painful joint condition) at bay. It helps flush toxins from your body that could inflame your joints, too.
And that's a good thing! As sweat evaporates from your skin, it cools down your body. Have a couple of extra cups of water in the couple of hours before you head out for exercise. Try to take about 10 big gulps every 15 minutes or so during your workout, too. Remember, you might not see the sweat you lose if you're in the pool or an air-conditioned gym.
You Avoid Dehydration
Without enough water, you can sweat away too much fluid. You can also lose sodium and potassium that your body needs. It's especially true in the heat. When it happens, you may be thirsty, pee less than usual, and your mouth might dry out. You could even feel dizzy, lightheaded, and confused.
Your Kidneys Stay Healthier
Water helps your kidneys remove waste from your blood. If you don't get enough water, that waste -- along with acids -- can build up. That can lead to your kidneys getting clogged up with proteins called myoglobin. Dehydration can also lead to kidney stones and urinary tract infections.
You Keep Your Brain Sharp
You may not remember as well, think as clearly, or concentrate as easily when you're low on water. And you don't have to be seriously dehydrated. It can happen if you're just a little below where you should be. How little? Less than 4 cups of water in a 150-pound person.
You May Gain an Athletic Edge
Even mild dehydration can make you tired. So it makes sense that athletes who replace the sweat they lose with water and electrolytes (minerals like sodium and potassium) have lower body temperature, more muscle, stronger hearts, more brain power, and more energy. It all adds up to better performance.
You Could Lose Weight
People who had just 2 or 3 more cups of water a day seem to have less fat, sugar, salt, and overall calories through the day. That means proper hydration could help you lose weight.
Extra water can replace empty, sugary calories many people drink with meals. Water also seems to speed up your metabolism, and it takes up space in your stomach so you feel more full.
Your Heart Works Better
Your ticker doesn't have to work as hard when you drink enough water. In fact, even mild dehydration affects your blood vessels (making them less springy) about the same as smoking a cigarette. Skimping on water also leads to less blood in your body, which can lower your blood pressure and raise your heart rate. It takes just 15 to 20 minutes for enough water to even things out.
You're Less Likely to Faint
You're less likely to pass out when you give blood if you've had enough water. The same seems to be true if you're careful to replace water lost through sweat or urine. When levels get a bit low, your blood pressure can drop and your nervous system can't control it as well. That could make you faint. Watch out for this if it's hot outside, and especially when you exercise.
How Much Is Enough?
A good rule of thumb is 15 cups a day for men and 11 cups for women. But keep in mind that includes total fluids. You get 20% to 30% of your water from food. You get more from other drinks like juice, tea, and milk. If you're sick, you'll need more (especially with diarrhea or vomiting). If you're exercising or outside in the heat, focus on getting a little extra, too.
Don’t Have Too Much
Too much water can dilute the salt in your blood enough to make you sick (it's called hyponatremia). Plus, you don't want to overdo it if you have certain health issues or take drugs that cause you to retain water, like NSAIDs, opiates, antidepressants, or others. Drink enough to keep a hint of yellow in the color of your urine, but not so much that it's always clear, or you spend all day in the bathroom. Talk to your doctor if you're unsure.