By Dr. Mercola
If you don't drink enough water, you can easily become dehydrated.
Many actually mistake their thirst for hunger, and this is one of the
basic premises behind the idea that drinking water may alleviate hunger
and help you lose weight.
Many studies support this idea though, so it's not just pure hype. Most
recently, researchers found that adults who were chronically
under-hydrated had higher body mass index (BMI) and were more likely to be obese compared to well-hydrated adults.1,2,3,4,5
A BMI of 25 is considered overweight; 30 obese. Those deemed
sufficiently hydrated had an average BMI of 28 whereas inadequately
hydrated individuals had an average BMI of 29.
While this study does not prove drinking more water will help you
lose weight, it does suggest staying well-hydrated is associated with
slightly lower body weight.
On the other hand, a 2013 systematic review of 11 studies and two other
meta-analyses concluded that while high-quality studies were still
lacking, increasing your water consumption when on a diet does appear to
be helpful for weight loss.6
Studies looking at general populations that were not necessarily trying
to lose weight found that increasing water consumption yielded
inconsistent results.
How Drinking Water May Aid Weight Loss
So is it all about filling your gut with water to alleviate hunger pangs? As explained by Authority Nutrition,7 there are actually a number of mechanisms at play. Studies have shown that drinking water may:
• Reduce your calorie intake.
If you drink more water, you're less likely to drink other beverages
such as soda, fruit juices and energy drinks, and this is, I believe,
the most significant factor that explains why higher water consumption
promotes weight loss.
Research suggests replacing other beverages with pure water typically lowers your overall caloric intake by about 9 percent, or 200 calories a day.8 • Reduce your appetite.
Interestingly, this effect has only been shown to hold true in older
subjects. Drinking water before meals had no discernible effect when
studied in children.9
In a 2010 study,10
adults who drank 500 milliliters (ml) of water prior to each meal lost
an additional 2 kilograms (kg) or 4.4 pounds over three months compared
to the non-water group.11
Another study12,13
published in 2015 had very similar outcomes. Adults who drank 500 ml of
water 30 minutes before each meal lost 3 pounds more weight over 12
weeks than those who did not preload with water.
Overall, they lost 4.3 kg, or 9 pounds, over the course of the study,
which is what you could expect from joining Weight Watchers for 12
weeks.
• Increase your resting energy expenditure,
meaning you burn more calories. While I doubt drinking water will help
you burn any significant amount of calories, some studies do suggest it
may give your metabolism a slight boost.
For example, adults who drank 500 ml or about 16 ounces of water
increased their metabolic rate by 24 and 30 percent respectively in two
separate studies.14,15 The metabolic rate began to rise within the first 10 minutes, and peaked around 30 to 40 minutes afterward.
In a third study, overweight women who drank in excess of 1 liter (L) or
34 ounces of water per day lost an extra 2 kg (4.4 pounds) of weight
over the course of a year.16
Overweight and obese children who drank 7.5 ml of cold water per kg
of body weight (averaging 518 ml) also had a 25 percent rise in resting
energy expenditure.17
How to Gauge Your Personal Water Requirement
As noted earlier, many of the studies looking at water consumption for
weight loss involve drinking 500 ml (16 ounces) of water before each
meal. That's basically two tall glasses of water. As for the
conventional recommendation to drink eight 8-ounce glasses of water per
day, there's no real science to back that up.
Water requirements are in fact extremely individual and can vary from
day to day, depending on your age, body size, activity level,
temperature and so on. Personally, I drink about three-fourths to 1
gallon of water per day, and I'm quite active under the Florida sun.
Three strategies that will help you gauge your water requirement on any given day are:
• Feelings of thirst.
Once your body has lost between 1 and 2 percent of its total water
content, it will signal its needs by making you feel thirsty.
Bear in mind the thirst reflex tends to be underdeveloped in children
and can be compromised in older adults, and by the time you actually
register thirst, you may already be somewhat dehydrated. If your mouth
is dry, that's a sign to rehydrate.
If you're an athlete, a 2 percent dehydration level is enough to cause a 10 percent decrease in athletic performance,18
and recent research shows driving while dehydrated reduces your
concentration and reaction time to the same degree as being legally
drunk and/or sleep deprived.19
For these tests, hydrated drivers drank 200 ml (6.76 ounces) every hour;
dehydrated drivers got only 25 ml (less than 1 ounce) of water an hour.
This kind of data may also hint at the amount of water you need in
order to optimize your brain function and physical performance.
• The color of your urine. You should be drinking enough water to turn your urine
a light-colored yellow. Dark-colored urine is a sign that your kidneys
are retaining fluids in order to maintain your bodily functions, which
includes detoxification. As a result, your urine will seem highly
concentrated and dark.
One caveat: riboflavin (vitamin B2; also found in most multi-vitamins)
will turn your urine a bright, almost fluorescent yellow, which will
make judging your water requirement based on the color of your urine
more difficult.
• Frequency of urination. A
healthy person urinates on average about seven or eight times a day. If
your urine is scant or if you haven't urinated in several hours, you
may need more water.
Other Signs and Symptoms Suggesting You May Need More Water
Other, more subtle signals indicating your body may be lacking in water include:20,21
Kidney stones are another "symptom" suggesting you may be chronically
dehydrated, as the No.1 risk factor for kidney stones is insufficient
water intake. If you aren't drinking enough, your urine will have higher
concentrations of waste products, including substances that can form
stones. Stone-forming chemicals such as calcium, oxalate, urate,
cysteine, xanthine and phosphate will have less chance to settle and
bond in your kidneys and urinary tract if you're urinating frequently.
According to the results of a large meta-analysis,22
presented at a National Kidney Foundation meeting in Dallas, Texas, in
2015, people who produced 2 to 2.5 L (approximately 68 to 84.5 ounces)
of urine per day were 50 percent less likely to develop kidneys stones
compared to those who produced scantier amounts. To generate that amount
of urine, people typically had to drink eight to 10 8-ounce glasses of
water daily.
Guidelines issued by the American College of Physicians (ACP) in 2014
call for those who have had kidney stones in the past to drink enough
water to produce 2 L (68 ounces) of urine each day, which they say can
reduce your chances of a recurrence by about 50 percent.23 The National Kidney Foundation (NKF) also recommends drinking more than 12 glasses of water a day to avoid stones.
Too Much Water Has Its Own Risks
While most people don't drink enough water for optimal health, too much
water also has its risks. You don't want to overdo it. As detailed in a
previous paper in the British Medical Journal (BMJ),24
excessive amounts of water can cause your sodium level to drop to a
dangerously low level, causing hyponatremia; a condition in which your
cells get waterlogged and swell.
While most cells can handle this swelling, your brain cells cannot, and
most of the symptoms are caused by brain swelling. Symptoms of
hyponatremia include:
This condition is most common among athletes who rehydrate excessively.
Clearly, staying well-hydrated is essential. But it may be unwise to
force yourself to drink a certain amount of water just because someone
said so. Remember, hydration needs are highly individual, and using your
thirst, the color of your urine and frequency of urination are the best
ways to gauge your personal needs on any given day.
Replacing Sugary Beverages With Water Is Key for Successful Weight Management
One of the first pieces of advice I offer to anyone trying to lose weight is to stop drinking soda,
fruit juice, sports drinks and any other sugar-laden, high-calorie
beverage. This is especially true of drinks containing high-fructose
corn syrup (HFCS), which has been shown to have the most adverse
metabolic consequences, fueling weight gain, non-alcoholic fatty liver
disease (NAFLD), high blood pressure, type 2 diabetes and more.
While many are getting savvy about the dangers of soda, fruit juice is
still considered "healthy" by most. This is a serious mistake. As
illustrated in this Health Science infographic, fruit juice is just as
hazardous as soda, and in some cases even more so. Replacing all sugary
beverages with pure water can make a significant difference if you're
trying to lose weight or improve your health.
It's important to recognize that your body loses water throughout each
day, even when you're not sweating, and that you need to constantly
replenish this fluid loss. While soda, fruit juices, sports drinks,
energy drinks and other beverages typically contain a fair amount of
water, they are poor substitutes for pure water and generally do not
count toward this requirement.
Many commercial beverages also contain diuretics like caffeine, which
will only dehydrate you more. So if you're thirsty, don't reach for a
caffeinated beverage.
Remember, research shows drinking just one can of soda per day can add
as much as 15 pounds to your weight over the course of a year.25
One sweetened beverage per day also increases your risk of developing
diabetes in the next decade by 18 percent, according to a 2015
meta-review.26,27
Previous research has shown this risk may be far higher than that.
Frequent soda drinkers also have a higher cancer risk, courtesy of both
its sugar content
— which has been identified as the top contributor to the surge in
cancer — and potentially carcinogenic ingredients like 4-methylimidazole
found in caramel color.28
Hydrate Well, but Be Mindful of Your Water Quality
So to stay well-hydrated, drink pure water. This is true when exercising as
well, as most sports drinks are loaded with sugars and other
questionable ingredients. Unless you have access to pristine well water
(which is quite rare these days) or a natural gravity-fed spring, 29 I strongly recommend filtering your water.
It can also be a good idea to "restructure" your water. I've previously
interviewed biomedical engineer Gerald Pollack, Ph.D., on the subject of
living, structured water.
His book, "The Fourth Phase of Water: Beyond Solid, Liquid, and Vapor,"
clearly explains the benefits of living water, or what he calls EZ water — EZ standing for "exclusion zone" — which has a negative charge.
This water can hold energy, much like a battery, and can deliver energy
too. This is the kind of water your cells contain; even your
extracellular tissues are filled with EZ water, which is why he believes
it's so important to drink structured water for optimal health. I drink
vortexed water (which increases EZ) nearly exclusively.
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Yes, water is key to hydration and supports a healthy diet and active life. With that said, soft drinks are not a unique risk factor for weight gain, type II diabetes, or other complex health issues. These products are deemed safe by the body of science, and regulatory agencies around the globe. Second, readers may be interested to know that water is the predominant ingredient in carbonated soft drinks. In fact, regular soft drinks are made up of 90 percent water, and diet soft drinks with zero calories are 99 percent water. These beverages, in addition to other options, can most certainly help fulfill hydration and can be enjoyed with the knowledge that these products are safe.
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Yes, water is key to hydration and supports a healthy diet and active life. With that said, soft drinks are not a unique risk factor for weight gain, type II diabetes, or other complex health issues. These products are deemed safe by the body of science, and regulatory agencies around the globe. Second, readers may be interested to know that water is the predominant ingredient in carbonated soft drinks. In fact, regular soft drinks are made up of 90 percent water, and diet soft drinks with zero calories are 99 percent water. These beverages, in addition to other options, can most certainly help fulfill hydration and can be enjoyed with the knowledge that these products are safe.
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