Water is essential to life, and your body needs it to function properly.
One trending idea suggests that if you want to be healthier, you should drink water first thing in the morning.
However, you may wonder whether the time of day really makes a difference when it comes to hydration.
This article reviews some popular claims surrounding the idea of drinking water right after you wake up to determine whether the practice offers any health benefits.
About 60% of your body is comprised of water.
It’s also considered an essential nutrient, meaning that your body cannot produce enough of it through metabolism to meet its daily needs (1Trusted Source).
Therefore, you need to get it through foods — and especially drinks — to ensure proper bodily function.
All organs and tissues depend on water, and it plays numerous roles in your body, including: (1Trusted Source)
Nutrient transportation. Water allows blood circulation, which transports nutrients to your cells and removes waste from them.
Thermoregulation. Due to water’s large heat capacity, it limits changes in body temperature in both warm and cold environments.
Body lubrication. Water helps lubricate joints and is an essential element of your body’s lubricating fluids, including saliva and gastric, intestinal, respiratory, and urinary mucous.
Shock absorbency. Water acts as a shock absorber, protecting your organs and tissues by helping maintain cellular shape.
Your body loses water daily through sweat, breath, urine, and bowel movements. These are known as water outputs.
If you don’t take in enough water throughout the day to make up for these losses, it can lead to dehydration, which is associated with many detrimental health effects (2Trusted Source).
This system is known as water balance and implies that water inputs must be equal to water outputs to avoid dehydration (1Trusted Source).
Water is an essential nutrient, and all organs and tissues in your body depend on it to function. Since your body loses water regularly, you need to compensate for these losses to avoid dehydration.
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Popular claims about drinking water on an empty stomach
Some people claim that drinking water first thing in the morning offers health benefits beyond those associated with drinking it at other times of the day.
Here are some popular arguments behind this claim and what science has to say about them.
Claim 1: Drinking water right after you wake up helps rehydrate your body
Because urine tends to be dark first thing in the morning, many people believe that they wake up dehydrated due to a lack of hydration during sleeping hours.
However, this is a half-truth, as urine color is not necessarily a clear indicator of hydration levels.
Though studies have determined that urine samples from first thing in the morning are more concentrated — resulting in a darker color, which is usually taken as a sign of dehydration — these samples fail to detect differences in hydration status (3Trusted Source).
One study in 164 healthy adults analyzed fluctuations in hydration levels and water intake. It determined that water intake was higher throughout the first 6 hours after waking up. Yet, their hydration levels did not reflect this increased water intake (4Trusted Source).
Despite having lighter-colored urine, they were not particularly well hydrated. That’s because large intakes of water can dilute urine, causing it to be a lighter or more transparent color — even if dehydration exists (1Trusted Source, 4Trusted Source).
Conversely, the darker color of your morning urine is not necessarily a sign of dehydration. It’s darker simply because you didn’t consume any liquids overnight.
When your body experiences a water deficit, it uses the sensation of thirst to ensure that you rehydrate. This sensation is equally efficient throughout the day (5Trusted Source).
Claim 2: A glass of water before breakfast reduces your calorie intake throughout the day
Evidence suggests that high water consumption helps reduce your daily calorie intake, as it increases your feelings of fullness (6Trusted Source, 7Trusted Source, 8).
While water can make you feel fuller, this effect does not exclusively apply to drinking water before breakfast — nor the general population.
One study found that drinking water before breakfast reduced calorie intake at the next meal by 13%. Although, another study observed similar results when participants drank water 30 minutes before lunch (9Trusted Source, 10Trusted Source).
That said, both studies concluded that water’s ability to reduce calorie intake at the subsequent meal was only effective in older adults — not in younger ones.
While drinking water before a meal may not significantly reduce calorie intake in younger individuals, doing so still helps them remain properly hydrated.
Claim 3: Drinking water in the morning increases weight loss
The relationship between water and weight loss is partly attributed to its thermogenic effect, which refers to the energy required to warm up cold water in the digestive tract after consumption.
Studies show that water-induced thermogenesis has the potential to increase the body’s metabolic rate by 24–30% in adults, and the effect lasts about 60 minutes (11Trusted Source, 12Trusted Source, 13, 14Trusted Source).
One study also determined that increasing your daily water intake by 50 ounces (1.5 liters) resulted in burning an extra 48 calories. Over 1 year, this totals about 17,000 extra calories burned — or about 5 pounds (2.5 kg) of fat (12Trusted Source).
Though this claim appears to be backed by scientific research, no evidence suggests that this effect is limited to water consumed first thing in the morning.
Claim 4: Drinking water upon waking improves mental performance
Dehydration is strongly linked to decreased mental performance, meaning that completing tasks, such as memorizing or learning new things, becomes more difficult (15Trusted Source).
Research shows that mild dehydration corresponding to 1–2% of body weight can negatively affect alertness, concentration, short-term memory, and physical performance (1Trusted Source, 5Trusted Source, 16Trusted Source).
Hence, some argue that if you want to stay on top of your game, you should drink a glass of water upon waking.
However, the effects of mild dehydration can be reversed by reintroducing fluids, and no evidence limits the benefits of rehydration to the early morning (5Trusted Source).
Claim 5: Drinking water first thing in the morning helps ‘eliminate toxins’ and improves skin health
Another common belief holds that drinking water in the morning helps your body “flush out toxins.”
Your kidneys are the primary regulators of fluid balance, and they do require water to eliminate waste from your bloodstream (5Trusted Source).
Yet, your kidneys’ capacity to clear your body of a given substance is determined by how much of the substance is present, not by your water intake or drinking schedule (1Trusted Source).
If a substance is present in an amount greater than your kidneys can handle, they induce the production of a large volume of urine. This is called osmotic diuresis and is different from water diuresis, which happens when you drink too much water (1Trusted Source).
There are also claims that drinking water boosts skin health. Given that your skin contains approximately 30% water, drinking it in the morning is thought to minimize acne and give it a moisturized look.
Though severe dehydration can reduce skin turgor and cause dryness, there is a lack of evidence to support this claim (5Trusted Source, 17Trusted Source).
Claim 6: It’s best to drink hot water in the morning
Another widespread opinion suggests that you opt for hot or warm water over cold water when you wake up, as it can soothe your body.
For example, warm water may benefit digestion in those who have trouble passing food and liquid from their esophagus to their stomach (18Trusted Source).
However, older studies have found that drinking warm water may interfere with hydration.
One such study simulated a long desert walk and noted that people who were given water that was 104°F (40°C) drank less of it, compared with those who were given water that was 59°F (15°C).
Given the desert-like conditions, the reduction in water consumption resulted in a loss of about 3% of body weight in the warm-water group, which increased their risk of dehydration.
On the contrary, those who drank the colder water increased their rate of intake by 120%, lowering their dehydration risk (19).
Claim 7: A glass of cold water in the morning jump-starts your metabolism
Some people argue that a glass of cold water jump-starts your metabolism, which in turn helps you lose more weight.
However, there seems to be a bit of controversy surrounding this claim.
Though one study showed that drinking water at 37°F (3°C) caused a 5% increase in the number of calories burned, this was considered to be a minimal increase, as cold water’s effect on how many calories you burn was expected to be higher (20Trusted Source).
Thus, the researchers doubted cold water’s ability to aid weight loss.
What’s more, another study analyzed whether the body would burn additional calories warming ingested water from 59°F (15°C) to 98.6°F (37°C) (12Trusted Source).
It concluded that about 40% of the thermogenic effect of drinking cold water was attributed to warming the water from 71.6°F to 98.6°F (22°C to 37°C) and only accounted for about 9 calories burned.
Independent of water’s temperature — they considered its effect on metabolism to be significant (12Trusted Source).
When it comes to favoring hot or cold water over the other, there isn’t enough evidence to confirm or reject either belief.
Drinking water provides numerous health benefits — whether it’s hot or cold. However, drinking it first thing in the morning doesn’t seem to increase its health effects.
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The bottom line
Water is involved in several bodily functions, including carrying nutrients and oxygen to cells, regulating body temperature, lubricating joints, and protecting your organs and tissues.
Though you may become mildly dehydrated at specific times throughout the day, no evidence supports the notion of drinking water on an empty stomach to reap added benefits.
As long as you compensate for your body’s water losses, it doesn’t make much of a difference whether you start your day off with a glass of water or drink it at any other time of day.
Just make sure you stay hydrated by drinking water whenever you feel thirsty.
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Last medically reviewed on October 25, 2019
Written by Ariane Lang, BSc, MBA on October 25, 2019 — Medically reviewed by Adda Bjarnadottir, MS, RDN (Ice)