Many studies support the theory that drinking water is beneficial for weight loss. Also, hydration is key for many factors that play a role in weight loss, including digestion and muscle function.

However, the medical community is still unsure about how much of an influence water consumption has on weight loss.

In this article, learn six reasons that drinking water may help a person to lose weight. We also look at how much water a person should drink each day.

Researchers are still unsure why drinking more water helps a person to lose weight, but many studies show some positive correlation between increased water consumption and weight loss.

Below are six reasons that water may help with losing weight.

1. Water is a natural appetite suppressant

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Drinking water may aid weight loss.

When the stomach senses that it is full, it sends signals to the brain to stop eating. Water can help to take up space in the stomach, leading to a feeling of fullness and reducing hunger.

A person may also think that they are hungry when they are actually thirsty. Drinking a glass of water before reaching for something to eat can help to curb unnecessary snacking.

In a 2014 study, 50 overweight females drank 500 milliliters (mL) of water 30 minutes before breakfast, lunch, and dinner, in addition to their regular water consumption, for 8 consecutive weeks.

The participants experienced a reduction in body weight, body fat, and body mass index. They also reported appetite suppression.

A study from the previous year had yielded similar results.

2. Water increases calorie burning

Some research indicates that drinking water can help to burn calories.

In a 2014 study, 12 people who drank 500 mL of cold and room temperature water experienced an increase in energy expenditure.

They burned between 2 and 3 percent more calories than usual in the 90 minutes after drinking the water.

Water may also temporarily increase the body's resting energy expenditure, or the number of calories burned while resting.

Drinking cold water may further enhance water's calorie-burning benefits, because the body expends energy, or calories, by heating up the water for digestion.

3. Water helps to remove waste from the body

When the body is dehydrated, it cannot correctly remove waste as urine or feces.

Water helps the kidneys to filter toxins and waste while the organ retains essential nutrients and electrolytes. When the body is dehydrated, the kidneys retain fluid.

Dehydration can also result in hard or lumpy stools and constipation. Water keeps waste moving by softening or loosening hardened stools.

Water also helps the body to recover from digestive problems, such as diarrhea and indigestion.

When waste builds up in the body, people may feel bloated, swollen, and tired. Bloating can add inches to a person's waist.

Staying hydrated is a good way to avoid retaining waste, which may add a few extra pounds.

4. Drinking water can reduce overall liquid calorie intake

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Water is a calorie-free alternative to energy drinks or juice.

It is easy to accumulate liquid calories by drinking soda, juice, or sweetened coffee or tea.

Most people also ignore how many calories they consume in sports drinks or alcoholic beverages.

Replacing even a few high-calorie drinks each day for water or other no-calorie beverages, such as herbal tea, may have long-term weight loss benefits.

Authors of a 2012 study found that replacing two or more high-caloric beverages for non-caloric drinks every day for 6 months resulted in an average weight loss of between 2 and 2.5 percent in a group of females with obesity.

In a study from 2015, female participants drank 250 mL of water after lunch each day while attending a 24-week weight loss program. They lost 13.6 percent more weight than women in the same program who drank the same volume of diet beverages after lunch.

Results of a large-scale study showed that men and women who replaced one serving of a sugar-sweetened beverage for water or a low-calorie drink every day for 4 years gained 0.49 fewer kilograms (kg) than a similar group who had made no changes.

The same study found that adults who replaced at least one serving of fruit juice with water or a low-calorie drink gained 0.35 kg less than their counterparts.

5. Water is necessary to burn fat

Without water, the body cannot properly metabolize stored fat or carbohydrates.

The process of metabolizing fat is called lipolysis. The first step of this process is hydrolysis, which occurs when water molecules interact with triglycerides (fats) to create glycerol and fatty acids.

Drinking enough water is essential for burning off fat from food and drink, as well as stored fat.

A mini-review from 2016 found that increased water intake led to increased lipolysis and a loss of fat in animal studies.

6. Water helps with workouts

One of the most important components of any weight loss plan is exercise.

Water helps muscles, connective tissues, and joints to move correctly. It also helps the lungs, heart, and other organs to work effectively as they ramp up activity during exercise.

Being hydrated reduces the risk of things that can get in the way of a good workout, such as muscle cramps and fatigue.

Always drink water before, during, and after exercise to avoid dehydration.

Keeping water close at hand is essential, especially if exercising in hot, humid, or very sunny conditions.

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Recommended water intake relates to factors such as age and health.

There is no standard recommendation for how much water to drink. Some people require more or less water, depending on a variety of factors, including:

  • activity level
  • age
  • body size
  • temperature
  • humidity
  • sun exposure
  • health status

Most health authorities suggest ranges for daily water intake. The following water intake recommendations are from the National Academy of Medicine (NAM) in the United States:

  • 2,700 mL/day for adult women
  • 3,700 mL/day for adult men

A 2013 study of results from the National Health and Nutritional Examination Survey 2005–2010 found that most adolescent males drink more water than NAM recommends each day.

However, results showed that many adults, especially older adults, did not drink enough water to meet NAM's guidelines.

Of the individuals aged 20–50, 42.7 percent of males and 40.6 percent of females did not meet NAM recommendations. Of those 71 years of age or older, 94.7 percent of males and 82.6 of females did not meet the guidelines.

The following tips can help to increase water intake:

  • drinking at least one 8-ounce glass of water with each meal
  • carrying water in a reusable water bottle
  • drinking extra water when exercising or during physical activity
  • drinking extra water when it is warm, humid, or very sunny
  • keeping a glass of water near the bed
  • eating more soups and liquid-rich meals, such as curries, stews, and smoothies
  • eating fruits and vegetables with high water contents, especially berries, grapes, melons, tomatoes, celery, cucumbers, and lettuce