As soon as you feel like you're thirsty, you're already dehydrated. So goes the accepted wisdom when it comes to necessary water intake in the body, but that's not the only sign you should be watching out for.

According to naturopathy expert Sal Graziano in the video above, as soon as you start exerting yourself more (both physically and mentally), your intake of protein and water has to go up as well. Yes, that's right -- it's not only workouts that make you dehydrated, but mental stress as well.

Other signs your body is already dehydrated include a lack of elasticity when you pinch your skin, a sticky mouth, and low to no urine output.

Equally as important is how the lack of water in your system can affect your cognitive processes. Studies earlier this year found dehydration to be the cause of bad moods and low energy, while other research has linked it to asthma and high blood pressure.

Wondering what can make you dehydrated? Check out these common causes to keep in mind:

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• Heating And Air-Conditioning

  Rooms that are too hot or too cold can both dry out your skin.

• Breathing

  Yes, the very act that keeps us alive can also make us dehydrated, particularly if you keep your mouth open over an extended period. This is why you may make up incredibly thirsty.

• Diarrhea

  When you have diarrhea, your body is likely getting rid of more fluids than it can take in. One of the most common causes of dehyration, it's important to keep drinking as much water as possible.

• Vomiting

  Much like diarrhea, as the body expels contents when vomiting, a lot of fluid goes with it. While it may be difficult to stomach, taking in fluids -- water or other water-heavy options -- can help you get back to normal more quickly.

• Obesity

  For those who are overweight, the water content in their bodies may automatically be lower (due to a higher presence of fat), thereby making them dehydrated. In certain studies, <a href="http://www.thisiswater.co.uk/blog/2011/10/dehydration-one-of-the-unrevealed-causes-of-obesity/" target="_hplink">dehydration has even been called out as causing obesity</a>, while drinking more water has been linked to weight loss.

• Chronic Diseases

  Chronic diseases, like diabetes, require more water from the body to process things that are lacking (like glucose), resulting in dehydration throughout.

• High Altitudes

  The higher the altitude, the lower the air pressure, and the more you sweat out from your body. Dehydration is often confused with altitude sickness, so if you're scaling any heights (and yes, that includes getting on an airplane), be sure to carry extra water.

• Sun Exposure

  It seems obvious, but that doesn't mean every beachgoer has water at the ready -- as you sit in the sun, you sweat, and as you sweat, you lose water in your body. Heat stroke has its basis in dehydration, so just because you're sitting beside the water doesn't mean it's enough.

• Aging

  As people age, their appetites and thirst tend to wane, making it more difficult to remember to drink as much and stay hydrated. As well, when we age the amount of water in our cells get reduced (resulting in things like wrinkled skin), so aging and dehydration truly do go hand in hand.

• Sweating

  Possibly the most overt sign of dehydration, when we sweat, we lose the water in our bodies, making it even more important to have drinks at the ready after a workout.

• Diet

  People get much of their hydration needs through their diet -- things like lettuce, milk, even steak all contain a large amount of water. But if your diet doesn't include water-rich options, and instead has a lot of fast food, for example, you won't be getting the same nutrients.

• Pregnancy

  Besides the dehydration that can result from morning sickness, there's also the work the body is doing in order to help the baby form properly. Pregnant women are advised to drink two cups of water every hour.

• Growing

  Similarly, as babies and children grow, their bodies require more water to help with the process. Parents must ensure their kids are getting enough each day, either with food or beverages.

• Crying

  While the amount of water that comes from your body when you cry isn't enough to cause dehydration, getting a headache after a particularly terrible bout of tears can indicate that you are dehydrated -- so get some water back into that body.

• Stress

  Like so many of these causes, this one works both ways -- if you're dehydrated, you're more likely to be stressed, and if you're stressed, you're more likely to get dehydrated. Moral of the story? Next time you feel yourself tensing up, take two minutes to get a drink of water.

• Hot Baths (And Hot Tubs)

  It sounds counterintuitive, but soak for long enough in a bath or hot tub, and your body will become more dehydrated, not less. You may not feel it, but you're sweating in that tub, and your body is losing all sorts of water. Keep a (preferably plastic) glass of water nearby so you can fully enjoy the soak without feeling sluggish afterwards.

• Burns

  Both sunburns and more serious burns cause dehydration. When skin is damaged, it can't retain fluid in the same way it does regularly, and results in overall dehydration.

• Alcohol

  As anyone who's ever had more than two drinks knows, alcohol is a diuretic, making you go to the washroom more and thereby pushing more fluids out of the body. Its effects are particularly noticeable the morning after a night of drinking, when a hangover headache is the direct result of the body's dehydration.

• Caffeine

  Much like alcohol, caffeine in coffee and tea are diuretics as well. While caffeinated beverages require a greater quantity to dehydrate the body (approximately five to seven cups of coffee a day), it's good to balance out your morning cuppa with water.

• Medications

  We've all seen labels on bottles of pills cautioning against 'dry mouth,' and this comes from the diuretic effect of certain medications. Common meds with these effects include menstrual pain options, high blood pressure pills and some antihistamines.

• Massage

  As your tissues get manipulated on the massage table, the water that's naturally contained within them goes to the kidneys to be expelled (the 'detoxifying' effects so many masseuses talk about). Be sure to drink at least three cups of water before a massage -- and of course, empty your bladder before the procedure starts.