More than half of children, according to an AJPH studyand 47% of adults aren’t drinking enough water each day. For some, it’s a matter of access, but for most, it’s just a matter of time management, intent, and bad habits. They’re so caught up in the chaos of everyday life — whether it’s their work schedule, caring for children, or dealing with daily struggles — that they forget how important it is to stay hydrated and drink enough water.

Even if they’re not obvious to the person experiencing them, there are many simple ways to tell if someone hasn’t been drinking enough water, according to research experts. From physical signs like chronic headaches to more subtle clues like food cravings, not drinking enough water can truly impact every part of their lives.

Here are 11 easy ways to tell someone hasn’t been drinking enough water, according to research:

1. They crave salty foods

Nattakorn_maneerat | Shutterstock.com

Since the fluids we consume often contain essential minerals like sodium that are vital for bodily functions, a person who is chronically dehydrated may crave these nutrients in other ways. If they aren’t getting enough sodium and electrolytes from staying hydrated, they’re more likely to crave salty foods to fulfill those needs.

Of course, feeling hungry and having a food craving are not the same thing, as a study from the Current Nutrition Reports journal suggests. When you experience a food craving, it’s often connected to internal processes rather than the amount of food you’ve eaten or your hunger levels.

So, if you’re craving salty foods, it might be a sign you’re not getting enough sodium or drinking enough water. But if you’re craving other things like fruits, you could be experiencing low blood sugar.

: 11 Simple Habits People Who Love Their Lives Practice Every Single Day

2. They always have dark circles

siro46 | Shutterstock.com

A 2015 study on dark circles shows that factors like family history, asthma, and allergies can all contribute to chronic dark circles under the eyes, but dehydration is also a common factor. Not drinking enough water and failing to get the essential nutrients from hydration can often make the skin under your eyes look dull.

That’s why it’s often one of the easiest ways to tell if someone hasn’t been drinking enough water, according to research, especially if they’re indulging in other healthy habits like getting enough sleep every night.

: 11 Things Fancy Sleep People Do Before Bed That Actually Work

3. They have chronic headaches

Ground Picture | Shutterstock.com

Although dehydration usually worsens existing health issues that cause headaches, making them more painful and prevalent, according to a study from the Current Pain and Headache Reports journalnot drinking enough water by itself can also trigger these problems.

Another study from the Journal of Clinical Neuroscience found that severe migraines, headache frequency, and their pain and duration were all significantly lower in people who regularly drank more water. So, even if headaches are triggered by other life events, stress, and physiological factors, drinking water can help reduce their effects.

: 5 Very Weird Reasons You Keep Getting So Many Headaches

4. They have dry skin

siro46 | Shutterstock.com

Water intake has very similar effects on skin quality as a topical moisturizer, according to a study from the Skin Research & Technology journal. So, if you’re not drinking enough water, your skin is likely one of the first signs to alert you.

Aside from superficial skin issues like dry skin, water intake also impacts overall skin healthincluding elasticity, acne, and cellular functions. As with many other signs that someone isn’t drinking enough water, research experts say that a person’s skin can also be affected by various factors, whether it’s their diet, exercise habits, or hygiene routine.

However, prioritizing water intake can benefit your body and mind in ways you might not even realize — sometimes even helping to lessen the severity of symptoms from chronic illnesses and mental health issues.

: I Drank A Gallon Of Water Daily For 3 Weeks (And Never Again)

5. They have bad breath

Antoniodiaz | Shutterstock.com

Bad breath, also known as “halitosis,” is one of the simplest signs that someone hasn’t been drinking enough water, especially if you see them daily, like a partner or coworker.

A study from the Journal of Oral Medicine and Pain found that dehydration, which is linked to lower salivation rates and high gas chromatography, often causes symptoms of halitosis. Even if it’s hard for the person experiencing it to noticebad breath is something others can easily detect, whether they are eating nearby or having a conversation.

: I’m A Dentist — These Are The 6 Odd Reasons Your Teeth Turn Yellow

6. They’re always low energy

Maria Gladkova | Shutterstock.com

Fatigue and low energy are often some of the easiest ways to tell someone hasn’t been drinking enough water, according to research experts. Naturally, the longer someone remains dehydrated, the more noticeable their exhaustion becomes, but even after just one day of poor hydration, it can start to cause problems.

Studies from the University of Connecticut even suggest that mild dehydration can cause energy fluctuations and impact a person’s mood. So, if you or a friend is thinking about investing in vitamins or supplements to increase your energy levels, first weigh the benefits of proper hydration, as Harvard Health experts recommend, which can often be more effective than you think.

: 11 Little Things That Drain Your Energy Without Even Noticing, According To Research

7. They struggle with concentrating

PeopleImages | Shutterstock.com

According to a study from the Medicine & Science in Sports & Exercise journaldehydration, especially over a prolonged period, can significantly affect cognitive function, attention, and motor coordination.

Whether it’s struggling to make decisions, critically thinking through problems at work, or even focusing on a demanding task at home, these are some of the easiest ways to tell if someone hasn’t been drinking enough water, according to research experts.

: 6 Low-Effort Habits That Make It Way Easier To Focus, According To Psychology

8. They have chapped lips

Antoniodiaz | Shutterstock.com

When you drink water, most of it goes to vital organs like your heart and brainbut your skin still benefits from hydration and essential nutrients. So, even if research on the specific benefits of drinking water for better lip health is limited, it could help address other internal issues that prevent moisture from staying in the skin.

So, if you’re always working out in the cold or standing in the sun without SPF protectionthose could all make the issue of chapped lips worse, especially if you’re not drinking enough water.

: 10 Habits The Healthiest People Do Before 10 AM Every Single Day

9. They struggle to recover after workouts

NDAB Creativity | Shutterstock.com

Hydration, electrolytes, and overall nutrition are all incredibly important for exercise — not only for performance and energy but also for recovery, as a study from the Journal of Human Kinetics suggests. Being dehydrated can impair flexibility and speedeven in top athletes, which can make energy levels and bodily recovery much harder.

When you’re not replenishing your body with the nutrients you’ve used up or lost after a workout, you’re left feeling worse off than when you started. So, if you see a teammate or friend consistently struggling with energy, mood, or overall well-being after exercise — especially when everyone else seems to recover — it’s likely they aren’t drinking enough water.

: 10 Reasons To Exercise That Improve Your Body And Mind — That Have Nothing To Do With Your Physical Appearance

10. They always get muscle cramps

Maya Lab | Shutterstock.com

According to a study from the BMJ Open Sport & Exercise Medicine journaldehydration makes muscles more prone to cramps, whether you’re sitting still or engaging in an activity. However, electrolytes and proper hydration can help to address those symptoms and uncomfortable muscle cramps — replenishing the minerals that are otherwise lacking internally.

That’s why people need to rehydrate — not just with plain water to prevent muscle cramps, as a 2012 study suggests, but also with electrolytes and sports drinks.

: The Small But Urgent Signs You Need To Drink More Water

11. They’re more irritable

The family | Shutterstock.com

There’s a strong connection between hydration and mental health, according to experts from the Cleveland Clinic, affecting everything from daily mood to serious diagnoses. Low hydration levels can often lead to issues like poor sleep, cognitive problems, and hormone imbalances that harm a person’s overall mental health.

So, even if they don’t realize at the time why they’re acting irritable or withdrawn, it’s one of the easiest ways for someone else to tell that they haven’t been drinking enough water.

: 7 Factors That Can Make Even Nice People Behave Rudely

Zayda Slave Choir is a senior editorial strategist with a bachelor’s degree in social relations & policy and gender studies who focuses on psychology, relationships, self-help, and human interest stories.