Does drinking water help you lose weight?

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Water and weight loss: An overview
The evidence
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Does drinking water help you lose weight? The evidence certainly suggests that it can. That being said, the issue is a little more complex than simply arming yourself with one of the best water bottles and making sure you’re chugging back enough of the cold stuff. Weight loss is contingent on lots of different components working together, but there’s no denying water plays an important part.

It should come as no surprise to you that water is essential for humans. From regulating body temperature, to maintaining blood levels, to transporting nutrients to and from cells, water is one of the most important substances for humans. And yet, a lot of us are suffering with anything from mild to chronic dehydration on a daily basis.

At the same time, the rate of adults who are overweight or obese continues to grow, as does the number of people who reporting being on weight-loss or low-calorie diets. It’s clear that more of us than ever before are wanting to shed those excess pounds and get healthy and while water clearly holds the answer to curing dehydration, it may also be the key to unlocking the body’s ability to maintain a healthy weight.

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Over 73% percent of adults in the US are overweight, and over 42% are living with obesity according to a CDC Report from 2018. This is not good news considering obesity and an increased BMI in general are associated with a tranche of health problems, outlined in detail in a 2017 paper in Annals of Translational Medicine. But can water really help us to lose weight, and, in doing so, give our health and wellbeing a much needed boost?

The first reason that water can benefit weight loss is that it’s totally calorie-free, so replacing sugary drinks, fruit juice and calorie-filled hot drinks with water can greatly reduce the number of calories you’re consuming every day. It’s probably quite obvious that eating or drinking foods that increase satiety (i.e make you feel more full) reduce the amount of food you eat, and thus your calorie intake as well, and many studies have shown that drinking water increases satiety and reduces hunger, as outlined in a review from the Proceedings of the Nutrition Society.

An important part of the calorie equation is exercise, as it’s the biggest part of the ‘calories out’ side that we can influence. Exercise and physical activity have been closely correlated to reductions in weight, maintenance of weight loss, and reductions in mortality risk factors, summarized in a 2018 review in Progress in Cardiovascular Diseases, and it’s natural for people to look to exercise as part of their weight loss routine.

With so many US adults dehydrated, and the body losing up to 65 fluid ounces of water per hour from sweat and respiration when exercising, many people aren’t getting the full benefit of exercise because of early fatigue due to dehydration, a process outlined in Nutrition Reviews. Between replacing calorie-filled drinks, feeling more full, and enabling more exercise, drinking water definitely seems like it can help with weight loss.

Analyses from a 12-month study on 173 women were published in Obesity, and the results are fascinating. Upon recruitment, all participants were classified as overweight, and reported drinking less than 35 fluid ounces (~4 cups) of water per day. At the 2-, 6-, and 12-month point, all of the subjects’ diet, physical activity, body weight, body fat percentage and waist circumference were assessed. For diet, the researchers assessed their average daily intakes of water, calorie-free, unsweetened caloric (e.g., 100% fruit juice, milk) and sweetened caloric beverages, and food calorie intake. They found that, independent of all other factors, increases in water intake were predictive of weight loss.

Another study in Obesity compared two groups of 150 people trying to lose weight. One group was assigned to drink 24 fluid ounces of water per day, and the other was instructed to drink 24 fluid ounces of artificially-sweetened, calorie-free drinks per day. Both groups lost weight, and the artificially-sweetened group actually lost more weight, but this shows again that drinking water can help you lose weight.

Finally, a systematic review from Hospital Nutrition compiled six Randomized Controlled Trials on the effects of water on weight loss, and found that subjects lost between 0.4kg and 8.8kg (0.9lb and 19.5lb) with an average percentage weight loss of 5.15%. These studies used various water drinking tactics: increasing daily water intake, replacing caloric beverages with water, and drinking water before meals. This is very solid evidence that drinking water can help you lose weight, especially when paired with other weight loss tactics like reducing calories and exercising.

If you’re looking to lose weight, deliberately drinking more water is a great idea. It can help you feel full, especially if you drink when hungry and/or right before a meal, it’s calorie-free, it can help you maintain exercise performance, and there is plenty of longer-term evidence to suggest that it can help improve and maintain weight loss. It can be difficult to remember to drink water, and you may not always have a glass and faucet nearby, so having a water bottle in easy reach is a great visual reminder to drink up.

Will McAuley is a London-based Personal Trainer and Nutrition Coach who’s writing has appeared in Men’s Fitness and GQ magazine, covering exercise, nutrition and health. He has a Master’s degree in Strength & Conditioning from Middlesex University in London, is a published scientific author in the Journal of Strength and Conditioning Research, and holds a Bachelor’s degree in Linguistics from Trinity College Dublin.

Does drinking water help you lose weight?

Water and weight loss: An overview

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Putting it all together