Dehydration occurs when your body is losing more fluid than it’s taking in, according to Dr Robert Segal, founder of the Medical Offices of Manhattan. That can happen with exercise, illness that causes diarrhoea or vomiting, and loss of body heat.
And it can lead to some pretty serious problems: Driving when you’re just one percent dehydrated, for instance, can lead to pretty dangerous behaviours behind the wheel, like lane drifting or late braking, according to a 2015 study. Plus, if you’re two percent or more dehydrated, your athletic performance might take a hit, too.
When the weather is toasty, it’s easy to remember to grab some water, but as it turns cooler, the chances of dehydration can increase, Dr. Segal notes. For example, if you’re running in chilly temps and you’re wearing multiple layers, it can be tougher to keep hydration in mind
But you should: When you don’t supply your body with enough fluids, you reduce functioning in every system, including our cells, tissues, and organs, he says.
There’s no one, set water prescription for every guy—it depends on things like diet and activity level. Still, there are some ways to know you’re not getting enough. Here, 5 signs you might be dehydrated.
SIGN OF DEHYDRATION: YOUR MUSCLES CRAMP
When you lose fluid, the nerve signals from your brain to your muscles don’t work as well, says Dr. Segal. So, it’s easier for muscles—especially in the legs, he says—to react by cramping.
Also, when you’re exercising and losing fluids, you’re creating an imbalance of electrolytes like sodium and potassium in your muscles. Not only does that up your odds of cramping, but it also increases your chances of feeling next-day soreness post-workout.
SIGN OF DEHYDRATION: YOU START CRAVING SWEETS
Organs like your liver use water to function, Dr. Segal says. One of those tasks is releasing glycogen, the molecule that stores sugar.
“If the liver can’t get fuel, it cannot release glucose and other energy stores,” he says. “What do we do in return to try to replace them? Eat.”
Sweet foods are especially attractive when this happens, he adds, so cravings for things like desserts or sugary drinks those could be a dehydration sign.
SIGN OF DEHYDRATION: YOU FEEL DIZZY
Part of hydration’s job is to regulate blood volume, including blood pressure. When you’re lacking in fluids, your blood pressure tends to lower, and that can lead to dizziness and lightheadedness, according to Dr David Greuner, head physician at NYC Surgical Associates.
He adds that dehydration also affects your vestibular system, which is responsible for keeping you in balance. So, in addition to your blood pressure drop, you may also feel vertigo and even become nauseated from feeling off balance.
SIGN OF DEHYDRATION: YOU PEE LESS
With nothing coming in, nothing’s going out. If you’re significantly depleted in your fluid stores, a dropping urine frequency will be a big sign, says Dr. Albert Ahn, clinical instructor of internal medicine at NYU Langone Health.
“If you normally pee every three or four hours and now it’s every eight to 10 hours, you’re likely dealing with some degree of dehydration,” he says.
That can be particularly dangerous because it means that your body isn’t getting rid of toxins as quickly as it should—you could even be setting yourself up for problems like kidney stones, a condition in which dehydration often plays a role, adds Dr. Segal.
RELATED: Is Sparkling Water Making You Fat?
SIGN OF DEHYDRATION: YOU CAN’T POOP
Hydration helps every part of your digestive system, from keeping your intestines lubricated and supple, to giving your poop enough moisture to pass out easily.
Without enough water, your stools can harden and then become difficult to get out, according to Heather Bartlett, M.D., a family practice physician in Columbus, Ohio.
Not only can that situation be frustrating, but it can also lead to development of symptomatic haemorrhoids from too much straining.
This article originally appeared on Men's Health