Medically reviewed on July 14, 2023 by Jillian Foglesong Stabile, MD, FAAFP. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.
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Water is vital to your health. In fact, getting the recommended daily water intake can help support many of your body’s vital processes, including cellular homeostasis, physical performance, and brain function. This is because 55% to 75% of body weight is composed of water weight, making it an essential component of your body and diet. 
That said, what role does water play in weight loss, and does drinking water help you lose weight?
Studies have found that water can have an effect on weight, although the relationship is not directly correlated. Rather, increased hydration can decrease feelings of hunger and can support the breakdown of fat molecules within the body to support weight loss. 
The Importance of Regular Hydration
Harvard Medical School recommends that men and people assigned male at birth (AMAB) drink 15.  cups of water daily, while women and people assigned female at birth (AFAB) drink 11.5 cups a day.  That said, your daily recommended intake will depend on several factors, including :
- Your activity level
- Temperatures in the area in which you live
- Your overall health
Even so, getting your recommended cups of water will not influence weight loss alone. While water intake aids in helping to regulate proper signaling of hunger and fullness cues, adequate hydration doesn’t cause weight loss directly. However, water can help support other bodily processes directly, including :
- Thermoregulation – Water is critical to your body’s ability to manage temperature control. When you’re in hot or humid environments, you often release much of the body’s water supply through sweat, thus cooling off the skin. Without an adequate source of water within the body, you may not be able to cool off adequately. In addition, if water intake doesn’t compensate sweat loss, your body can enter a hypohydrated state in which your core body temperature increases.
- Physical performance – When participating in rigorous physical activity, people can lose up to 10% of their body weight in sweat loss, leading to potential dehydration and decreased physical performance. As such, it’s critical to replenish your body with enough plain water during exercise to regulate your core body temperature, increase endurance, and mitigate fatigue.
- Cognitive performance – Dehydration is known to disrupt mood and cognitive functioning related to short-term memory, perceptual discrimination, arithmetic ability, visuomotor tracking, and psychomotor skill. One study also found that increased water consumption increased levels of alertness among participants.
- Gastrointestinal function – Many factors can cause constipation, including inadequate fiber intake, poor diet, and illnesses. Water intake may also play a role. Increasing fluid intake can support gastrointestinal flow and can reduce the frequency of constipation episodes.
- Kidney function – Regular water intake can help support the kidneys, which works to regulate water balance and blood pressure within the body. Additionally, the kidneys require water to filtrate waste from the blood, to dilute it, and to remove the waste through urine.
- Heart health – As stated, drinking enough water can have a positive effect on your blood pressure. It may also impact your blood volume and heart rate, both of which are closely linked to blood pressure. Conversely, dehydration can decrease blood volume and reduce your heart rate, which can have a negative impact on the body.
- Migraine prevention – Dehydration may also lead to headache symptoms which can, in turn, impair cognitive functioning and increase irritability. While studies have not yet found a link between water consumption and a reduced number of migraine episodes, water is believed to reduce the intensity of migraine symptoms.
- Skin health – The skin is composed of 30% water, contributing to its resilience and plumpness. As such, increased water intake may improve skin plumpness and elasticity.
The Connection Between Water and Weight Loss
Increased hydration may also lead to weight loss, albeit indirectly. More specifically, animal studies have found an association between increased water intake and decreased weight. Similarly, insufficient water levels in the body are correlated with increased body weight. 
So, what exactly is the connection between water intake and weight loss? It’s believed that proper hydration is associated with two mechanisms :
- Decreased feeding – In one study, researchers found that doubling the amount of water rats drank decreased their appetite. As appetite waned, so too did the rats’ body weights, since food intake also decreased. It’s believed the same mechanisms function within humans. 
- Increased lipolysis – Lipolysis describes the metabolic process in which the body breaks down stored fat molecules into fatty acids and glycerol. In another animal study, researchers observed that increasing fluid intake by 30% to 50% led to a loss of body fat in obese mice.2 It also improved insulin sensitivity in rodents, and similar results were found in one human study, as well. 
Have you ever wondered how to speed up your metabolism? It’s believed that drinking cold water may help stimulate your metabolism and increase energy expenditure since your body must use energy to heat the water to body temperature. In fact, in a 2003 study, researchers found that drinking two cups of water at 71 degrees Fahrenheit increased participants’ metabolic rates by 30% on average. 
Get Personalized Weight Management Support with Everlywell
Increasing your daily water intake may help facilitate weight loss by decreasing your appetite, increasing fat loss, and stimulating your metabolism. However, if your daily water intake still isn’t supporting your weight management efforts, consider reaching out to Everlywell.
Ready to reach your weight goals? Our online weight management services can provide you with one-on-one consultations with a licensed clinician. They can monitor your health and assess your lab results to show you the best path forward in your weight loss journey. Reach out today to learn more.
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- Popkin BM, D’Anci KE, Rosenberg IH. Water, Hydration, and Health. Nutrition Reviews. 2010;68(8):439-458. URL. Accessed June 14, 2023.
- Thornton SN. Increased Hydration Can Be Associated with Weight Loss. Frontiers in Nutrition. 2016;3. URL. Accessed June 14, 2023.
- Harvard Health Publishing. How much water should you drink? Harvard Health. Published March 25, 2020. URL. Accessed June 14, 2023.
- Shimabukuro M, Tanaka H, Shimabukuro T. Effects of telmisartan on fat distribution in individuals with the metabolic syndrome. Journal of Hypertension. 2007;25(4):841-848. URL. Accessed June 14, 2023.
- Johns Hopkins University. Yes, drinking more water may help you lose weight. The Hub. Published January 15, 2020. URL. Accessed June 14, 2023.