Water and Weight Loss

Purpose of this article

To summarize the effect of drinking additional water on energy expenditure and diet outcomes.

Disclaimer: I am not a doctor, and nothing in this article should be considered medical advice.

Summary

Drinking sufficient water daily is very important for overall general health, but research has only shown modest benefits of drinking additional water for the purposes of weight control. Overweight and obese individuals on a low-calorie diet may see some increased benefit, but the effect size is unclear and more research is needed. However, given that there are very few drawbacks, additional water intake can be considered an additional tool for individuals struggling with weight loss or maintenance.

Key points

• Adequate water intake has been established by the Institute of Medicine and the World Health organization as somewhere between 2 and 5 liters per day depending mainly on sex, physical activity, and exposure to hot temperatures. (WHO, 2004)(Institute of Medicine, 2005).


• The CDC, AMA, and other government and health organizations both in the US and internationally promote drinking water for weight management, but the research is not clear that this recommendation is sound (Stookey, 2016).


• Systematic reviews show that the overall quality of research studies on this topic has been relatively poor, and there is currently only weak evidence to support the hypothesis that water has a significant effect on weight reduction in adults (Muckelbauer, 2013; Stookey, 2016).


• However, some research provides evidence that drinking additional water may be more effective for overweight or obese individuals on low calorie and/or low glycemic diets (Stookey, 2016).


• The thermogenic effects of water intake (increased energy expenditure) appear to be relatively minor. Research has found that drinking water alone can increase resting energy expenditure by somewhere between 1% and 25% for approximately 90 minutes after water intake. However. the more recent, and arguably higher quality, research indicates that the number is probably in the 3-5% range. Therefore, drinking large amounts of increased water per day should not, in isolation, result in a significant number of additional calories burned per day. (Kocelak, 2012; Charriere, 2015).
  
  
  
  • It should be noted that in most studies, drinking cold water increased resting energy expenditure to a greater extent than room temperature water. Some studies suggest that most of the thermogenic effect of water drinking may be explained by the body having to warm the water to body temperature. (Kocelak, 2012; Girona, 2014).
  
  
  • Some factors mediating an increase in energy expenditure from drinking water seem to be whether the individual is obese, whether the water ingested is cold or room temperature, and (possibly) the composition of the water (i.e. distilled vs. tap) (Boschmann, 2003; Kocelak, 2012; Girona, 2014; Charriere, 2015).
  
  
• Aside from possible thermogenic effects, there are indirect benefits for drinking additional water during weight loss:
  
  
  
  • Reduced feelings of hunger and consumption of fewer calories during meals has been reported when a moderate quantity of water is taken at some point before a meal (typically around 30 minutes) (Dennis, 2009; Daniels, 2010; Muckelbauer, 2013).
  
  
  • Replacement of caloric drinks with water. This one is kind of obvious, but much of the research has been focused here. Indeed, if you replace soda, juice, and other caloric drinks with water, your total caloric intake will decrease.
  
  


• Despite the relatively modest effects of additional water intake on weight control, this could still make a significant difference at both the population level and even for the individual over the long-term.
  
  
  
  • For example, if we combine the modest thermogenic effect of increased water intake with reduced feelings of hunger and reduced calorie consumption during meals with water “pre-loading”, it is very possible that one could see a ~100 kcal/day difference in overall energy balance. This could result in approximately 10 pounds (~4.5kg) of additional weight loss over the course of a year, and even a more conservative 50kcal/day would still offer long-term benefits for weight maintenance.
    
    
  • If we consider replacement of caloric beverages with water as an additional benefit of increased water consumption, this number could be much, much greater for many individuals. (I don't think it is fair to call this a benefit of additional water intake, though. It is really just the benefit of abstaining from calorie-containing beverages, so it's a bit dishonest to call this a benefit of water despite much the research doing so).
  
  
• Over-consumption of water does not seem to be something concerning for most healthy individuals outside of extreme cases. Some people with specific medical conditions should be mindful of adverse effects from drinking too much water too quickly, especially in the absence of sodium intake. It would be advisable to check the Institute of Medicine guidelines and/or seek medical advice depending on your circumstances (Institute of Medicine, 2005).

Thermogenic effect of water intake

Two studies by Boschmann(2003; 2007) provided early evidence that drinking water alone could account for an increase in resting energy expenditure, and this has been referred to as the thermogenic effect of water. In the first of these studies, Boschmann found that drinking a half-liter of water in the absence of food increased the metabolic rate of participants by up to 30% for approximately an hour after drinking (with peak increase after 30-40 minutes). The researchers hypothesized that increased sympathetic activation after drinking was the mechanism that most likely explained the differences in energy expenditure.

Boschmann et. al followed up 4 years later with a randomized, controlled trial seeking to replicate these effects and found that 500ml of water increased energy expenditure by 24% for approximately an hour after drinking. These large effect sizes are striking because they suggest that the simple act of drinking an additional few liters of water per day could lead to significant weight loss over even the medium-term. Dubnov-Raz and colleagues replicated this effect in 2011 in a study with children, with one important difference being that these researchers used cold water (Dubnov-Raz, 2011).

Unfortunately, follow up research since these studies has found a significantly smaller thermogenic effect. They also discovered that the temperature of the water ingested may account for a significant portion of the variation in increased energy expenditure. In 2006, Brown et al. found that drinking cold water resulted in an increased energy expenditure of approximately 4.5% over an hour. Kocelak(2012) also used cold water and found an increase in energy expenditure between 12 and 20% after drinking cold water depending on the weight of the individual. The researchers concluded that the increase in energy expenditure was mostly related to heating the cold water to body temperature.

Charriere (2015) found that drinking distilled water led to an increase in energy expenditure of only 3%. Using distilled water is an interesting change in methodology, and it is possible that the water composition (distilled vs. tap, for instance) is a relevant factor in determining water's thermogenic effect. Girona (2014) found an increase of 2.3% (for room temperature water) to 2.9% (for cold water). Drinking body-temperature water (37C) did not result in a significant increase in resting energy expenditure.

In summary, most studies in the last decade have provided evidence for a real but relatively small increase in resting energy expenditure over baseline that is more pronounced as the temperature of the ingested water decreases.

Conclusions of systematic reviews

Several systematic reviews have been published on this topic in the last 15 years, so we will take a brief look at two of them.

I generally found Muckelbauer(2013) to be the most helpful high-level summary of the issue. One of the main takeaways from this paper is the emphasis that the quality of the studies done on this topic has been poor in general. One reason is that there is a lack of controlled, randomized trials to effectively study this issue, and so it is difficult to properly establish causal links. Another issue brought up by the researchers is that there is a significant potential for bias since many of the studies providing some evidence for weight change with increased water consumption were at least partially funded by the water industry.

Another issue touched on is the fact that many of the studies on this topic focus on the replacement of high calorie beverages with water, and in my opinion those studies are not telling us anything very interesting. If you consume less calories each day as a result of drinking less soda, juice, and other calorie beverages, it is not a surprise that replacing these with water is associated with weight loss. Overall, the researchers found that the effects of drinking additional water on total energy expenditure were quite modest.

The mechanisms for the observed effects were hypothesized to be mainly explained by the hunger-suppressing effects of drinking water before meals resulting in less overall calories consumed over the course of the proceeding meal. Thermogenic effects of water are only briefly discussed, but the researchers suggest that this effect is likely only minor based on recent research.

Stookey(2016) provides a similar story. The overall effects of drinking additional water appear to be modest, but this paper focuses more heavily on individual differences and identifying which groups of people may benefit more significantly from increased water consumption with respect to weight change and fat oxidation. Unsurprisingly, the replacement of calorie beverages with water tends to provide the biggest effect size for overall energy expenditure, and we are already discussed why this is not particularly surprising or interesting.

However, the researchers identified a particular group of people who may especially benefit from increased water intake – overweight or obese individuals on a hypocaloric or low glycemic diet. This category likely covers the majority of people looking to lose weight, so it is particularly relevant to us. It is not yet clear from the research why overweight or obese individuals on a low calorie diet may see this increased benefit.

According to the paper, these conditions “would be hypothesized to accelerate weight loss by increasing energy expenditure and/or fat oxidation by reducing osmotic stress on cells, improving insulin resistance, reducing gluconeogenesis and/or improving postprandial glucose clearance”. A complete review of these possible mechanisms is beyond the scope of this article, but future research exploring these mechanisms in the context of water intake and weight loss in randomized, controlled trials would be interesting.

Why was this article needed?

I was not able to find a reliable, trustworthy, and comprehensive source of information about this topic available online. Most of the available information topping search results on this topic is listed on unreliable sites without adequate references. Other articles have some reliable data but focus too narrowly on a single study or come to broad conclusions without proper support.

This article is an attempt to look at the available research, provide a decent summary on the topic, and provide a useful list of references for those seeking more information on the topic.

Most helpful articles for further reading

• Muckelbauer, R., Sarganas, G., Gruneis, A., & Muller-Nordhorn, J. (2013). Association between water consumption and body weight outcomes: A systematic review. The American Journal of Clinical Nutrition, 98(2), 282-299. doi:10.3945/ajcn.112.055061


• Institute of Medicine (2005). Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. doi:10.17226/10925


• Stookey, J. (2016). Negative, Null and Beneficial Effects of Drinking Water on Energy Intake, Energy Expenditure, Fat Oxidation and Weight Change in Randomized Trials: A Qualitative Review. Nutrients, 8(1), 19. doi:10.3390/nu8010019

References

Boschmann, M., Steiniger, J., Hille, U., Tank, J., Adams, F., Sharma, A. M., … Jordan, J. (2003). Water-Induced Thermogenesis. The Journal of Clinical Endocrinology & Metabolism, 88(12), 6015-6019. doi:10.1210/jc.2003-030780

Boschmann, M., Steiniger, J., Franke, G., Birkenfeld, A. L., Luft, F. C., & Jordan, J. (2007). Water Drinking Induces Thermogenesis through Osmosensitive Mechanisms. The Journal of Clinical Endocrinology & Metabolism, 92(8), 3334-3337. doi:10.1210/jc.2006-1438

Brown, C. M., Dulloo, A. G., & Montani, J. (2006). Water-Induced Thermogenesis Reconsidered: The Effects of Osmolality and Water Temperature on Energy Expenditure after Drinking. The Journal of Clinical Endocrinology & Metabolism, 91(9), 3598-3602. doi:10.1210/jc.2006-0407

Charriere, N., Miles-Chan, J. L., Montani, J., & Dulloo, A. G. (2015). Water-induced thermogenesis and fat oxidation: A reassessment. Nutrition & Diabetes, 5(12). doi:10.1038/nutd.2015.41

Cruz, A. J., Bracamontes-Castelo, G., & Bacardi-Gascon, M. (2019). Effect of water consumption on weight loss: A systematic review. Nutricion Hospitalaria. doi:10.20960/nh.02746

Daniels, M. C., & Popkin, B. M. (2010). Impact of water intake on energy intake and weight status: A systematic review. Nutrition Reviews, 68(9), 505-521. doi:10.1111/j.1753-4887.2010.00311.x

Dennis, E. A., Dengo, A. L., Comber, D. L., Flack, K. D., Savla, J., Davy, K. P., & Davy, B. M. (2009). Water Consumption Increases Weight Loss During a Hypocaloric Diet Intervention in Middle-aged and Older Adults. Obesity, 18(2), 300-307. doi:10.1038/oby.2009.235

Dennis, E. A., Flack, K. D., & Davy, B. M. (2009). Beverage consumption and adult weight management: A review. Eating Behaviors, 10(4), 237-246. doi:10.1016/j.eatbeh.2009.07.006

Dubnov-Raz, G., Constantini, N. W., Yariv, H., Nice, S., & Shapira, N. (2011). Influence of water drinking on resting energy expenditure in overweight children. International Journal of Obesity, 35(10), 1295-1300. doi:10.1038/ijo.2011.130

Girona, M., Grasser, E. K., Dulloo, A. G., & Montani, J. P. (2014). Cardiovascular and metabolic responses to tap water ingestion in young humans: Does the water temperature matter? Acta Physiologica, 211(2), 358-370. doi:10.1111/apha.12290

Grading quality of evidence and strength of recommendations. (2004). BMJ, 328(7454), 1490. doi:10.1136/bmj.328.7454.1490

Institute of Medicine (2005). Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. doi:10.17226/10925

Kocelak, P., Zak-Golab, A., Rzemieniuk, A., Smetek, J., Sordyl, R., Tyrka, A., … Olszanecka-Glinianowicz, M. (2012). The influence of oral water load on energy expenditure and sympatho-vagal balance in obese and normal weight women. Archives of Medical Science, 6, 1003-1008. doi:10.5114/aoms.2012.32406

Muckelbauer, R., Sarganas, G., Gruneis, A., & Muller-Nordhorn, J. (2013). Association between water consumption and body weight outcomes: A systematic review. The American Journal of Clinical Nutrition, 98(2), 282-299. doi:10.3945/ajcn.112.055061

Pan, A., Malik, V. S., Hao, T., Willett, W. C., Mozaffarian, D., & Hu, F. B. (2013). Changes in water and beverage intake and long-term weight changes: Results from three prospective cohort studies. International Journal of Obesity, 37(10), 1378-1385. doi:10.1038/ijo.2012.225

Parretti, H. M., Aveyard, P., Blannin, A., Clifford, S. J., Coleman, S. J., Roalfe, A., & Daley, A. J. (2015). Efficacy of water preloading before main meals as a strategy for weight loss in primary care patients with obesity: RCT. Obesity, 23(9), 1785-1791. doi:10.1002/oby.21167

Rolling Revision of the WHO Guidelines for Drinking-Water Quality. (2004, August). Retrieved from https://www.who.int/water_sanitation_health/dwq/nuthardness.pdf

Stookey, J. (2016). Negative, Null and Beneficial Effects of Drinking Water on Energy Intake, Energy Expenditure, Fat Oxidation and Weight Change in Randomized Trials: A Qualitative Review. Nutrients, 8(1), 19. doi:10.3390/nu8010019

Stookey, J. D., Constant, F., Popkin, B. M., & Gardner, C. D. (2008). Drinking Water Is Associated With Weight Loss in Overweight Dieting Women Independent of Diet and Activity. Obesity, 16(11), 2481-2488. doi:10.1038/oby.2008.409

Thornton, S. N. (2016). Increased Hydration Can Be Associated with Weight Loss. Frontiers in Nutrition, 3. doi:10.3389/fnut.2016.00018

Walleghen, E. L., Orr, J. S., Gentile, C. L., & Davy, B. M. (2007). Pre-meal Water Consumption Reduces Meal Energy Intake in Older but Not Younger Subjects. *Obesity, 15(1), 93-99. doi:10.1038/oby.2007.506

Published: September 21, 2020.

Last updated: December 6, 2020

Correction and Edit History:

• 12/6/2020: Minor formatting changes and typo fixes

*License Info: This article is licensed under Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)