Does Water Help You Lose Weight?

glass of water sits on wood table

Drinking water and weight loss just seems to be one of those things that always get lumped together, although a lot of diets don’t really explain why you should drink more water to lose weight. They just tell you to do it.

While water has all kinds of health benefits, and can certainly be part of a healthy diet (and may assist in weight loss), it’s important to have realistic expectations around the role of water when it comes to losing weight and excess body fat. You won’t simply drink more water and experience dramatic weight loss. I hate to say it, but it’s true.

Remember, when it comes to weight loss, there are no silver bullets — although there are plenty of tactics that you can combine together to be more successful in your goals. And yes, drinking more water can be one of them.

Why Is Water Important?

First, let’s tackle why water is important to the body and your general health and well-being. We’ll then address your question about whether water can make you lose weight.

Water is the most abundant substance in the human body. It accounts for 55-78% of your body’s total weight, depending on age and gender. Water plays a critical role in everything from regulating your body’s temperature and supporting metabolic processes to maintaining proper pH balance and carrying waste from the body via the kidneys.

In fact, water plays such a vital role in human life that although a person can survive for weeks without food, they can only survive, at most, 10 days without water.

As a person becomes dehydrated, their ability to perform work and support basic human functions becomes impaired as well.

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For every 2.5% loss of water as a percentage of body weight, you lose around 25% of your efficiency. That would be only about 2 quarts for a 175 lb man. As you become dehydrated, your blood becomes thicker, increasing your blood pressure and placing more stress on your cardiovascular system, as well as interfering with your mental and physical abilities.

Will Water Make You Lose Weight?

Drinking more water can help you lose weight, but not necessarily in the ways that many people think.

Water isn’t a drug (although it is a chemical, with solvent properties which are beneficial in the body), so don’t expect to simply add a couple of extra glasses of water in a day, and suddenly see the belly fat start to melt off.

Drinking more water supports weight loss in a number of direct and indirect ways:

  • Water has zero calories, making it a great substitute for higher-calorie beverages like soda or juice
  • Drinking water maintains a healthy baseline metabolism, and may actually contribute to a slightly higher metabolism. There is some evidence that water temperature and weight loss are related. For example, drinking ice water may enhance this metabolic effect, since the body must expend extra energy to warm the water during digestion. However, this increase in energy expenditure will be marginal. Then again, every little bit counts.
  • ​Because water has no calories, it will not contribute calories to your daily energy balance. In fact, water is probably the only truly “negative calorie” food, since your body will expend a few extra calories (and we are talking less than a half-dozen here) digesting water.
  • ​Drinking more water, both before and during meals can increase satiety, make you feel fuller and discouraging overeating.
  • ​Keeping yourself adequately hydrated actually encourages your body to release water from tissue, which eventually may lower scale weight due to “water-weight” or water retention. While this reduction in water weight does not necessarily signal loss of body fat, you can appear leaner with increased water consumption.
  • Water is essential for metabolizing fat and flushing the bi-products of fat oxidation (fat burning) from the body. Ensuring proper hydration allows the liver and kidneys to do their job, maintaining normal metabolic efficiency.
  • ​Drinking plenty of water and maintaining proper hydration ensures that the body can perform at peak efficiency. This is especially important if you are including exercise (both cardiovascular and weight or resistance-type training) in your fat loss and fitness plan. Dehydration can reduce your body’s ability to function properly, reducing peak performance during physical activity. This means you won’t be getting everything you should out of exercise if you’re not drinking enough water.
  • ​Water supports overall health. New research indicates that increased fluid consumption in general and water consumption in particular can have an effect on the risk of urinary stone disease; cancers of the breast, colon, and urinary tract; childhood and adolescent obesity; mitral valve prolapse; salivary gland function; and overall health in the elderly.

What Does the Research Say About Water To Lose Weight?

Over the past decade, there has been a flurry of clinical research into how drinking more water may help with weight loss.

So far, the results have been encouraging, although researchers admit that they still need additional data to determine the long-term effects of increased water consumption on weight loss and body composition.

A number of recent studies have shown that increased water consumption can lower total energy intake, regardless of diet, by as much as 200 calories day. This is probably due to the satiety and fullness effect of water, although researchers also hint that it may be caused by alterations in metabolism.

A 2006 study by Children’s Hospital Oakland Research Institute found that female, overweight dieters who consumed 2 or more cans of soda or juice a day experienced an average weight loss of 5 lbs a year when they substituted the same amount of water for sweetened beverages. Those who drank four or more glasses a day, lost 2 more lbs a year versus dieters who did not drink that amount of water.

Clearly, when people substitute water for high-calorie beverages like soda or juice, they tend to experience weight loss due to decreased energy intake. Drinking water instead of soda or sugary fruit beverages also avoids some of the pitfalls of substituting diet or artificially-sweetened beverages for regular soda, which has actually been shown to increase body weight in a number of studies.

How Much Water Should You Drink To Lose Weight?


While there is no recommended amount of water that people should drink specifically to lose weight, in general, more water is better. While is is possible to drink too much water (resulting in a potentially lethal condition known as hyperhydration or “water poisoning”), this is rare, and requires a specific set of circumstances to develop.

How much water a person should drink each day continues to be a topic of debate, even within the medical community.

The “Eight Glasses a Day” recommendation that always seems to be thrown around appears to be arbitrary — even experts on hydration aren’t exactly sure of the origins of this recommendation.

While there is no harm in following the “Eight Glasses a Day” rule of thumb, even if you only drink four glasses of water a day, you’ll consume around four additional cups of water just from your food. And believe it or not, even caffeinated beverages like tea and coffee count toward your daily fluid requirements.

Research has shown the diuretic effects of caffeinated beverages are over-stated, and that the body adjusts fairly quickly to them. In fact, a 2006 study published in the European Journal of Clinical Nutrition found that drinking tea may be healthier than drinking water. So if you enjoy a few cups of green or black tea a day, keep it up.

In terms of weight loss and general overall fitness and health, the best approach is drink however much water works for you.

If you find drinking plenty of water across the day keeps you feeling fuller, more energetic and helps you eat less during meals, then don’t change what’s broken. If you aren’t a regular water drinker, start becoming one. Expect that as you increase your fluid consumption, you may also find yourself initially having to make trips to the bathroom more often. Don’t worry — this is common at first and your body will eventually regulate itself.

What if you just find water to be … blah? Consider trying one or more of these five tricks to jazz up plain old tap water and make it tastier and more appealing.

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