Could losing weight really be as simple as drinking plain water? The answer is yes. And no.
According to research, drinking plain water may be an effective weight loss tool for a few different reasons.
A small number of studies in adults and children have shown that drinking the recommended 2.1-2.6 litres of water per day can briefly increase the amount of energy your body burns by inducing thermogenesis.
"The research is showing that plain water consumption -- so, not salted water or diet soft drinks -- does cause a small but significant increase in energy expenditure, or the number of kilojoules that your body burns," Associate Professor Amanda Salis from The University of Sydney's Boden Institute of Obesity, Nutrition, Exercise and Eating Disorders told The Huffington Post Australia.
"It is small and it only increases for about an hour, but it’s been calculated that drinking the recommended amount of plain water can result in about 1.2 kilograms of weight loss over the year due to this effect -- assuming everything else, like diet and exercise, stays the same."
This is not to say drinking more water is a quick fix for weight issues. However, combined with regular exercise and a healthy diet, it could be a helpful tool.
"Considering people tend to gain about one kilogram per year, every year in their later adult years, you need all the help you can get," Salis said.
Aside from water consumption potentially increasing energy expenditure, drinking water has other weight management benefits.
"It has been shown in small trials that if you drink a large glass of water before a meal, it reduces the amount of food you eat overall. So, drinking water has a two-pronged effect: potentially increasing the amount of kilojoules you burn and potentially decreasing the amount of kilojoules you consume," Salis said.
Because plain water is kilojoule-free, drinking it in place of milky coffees, fruit juices, soft drinks and alcohol will reduce your overall energy intake and can help promote weight loss.
"We do know that drinking plain water does help with weight management due to the fact that it’s replacing kilojoule-containing beverages," Salis told HuffPost Australia.
"Liquid kilojoules are really dangerous in terms of weight management," Salis said.
"Kilojoules from fruit juice or alcohol isn't registered by our bodies in the sense of feeling satisfied. For example, you might drink 500 kilojoules from a fruit juice but it won’t have any impact on how satisfied or full you feel. On the other hand, if you eat the same number of kilojoules of a solid food, your body will register those kilojoules, so the next time you eat you’ll naturally eat fewer kilojoules.
"Drinking kilojoules leads to this passive overconsumption where we consume more kilojoules than we normally would. That’s an advantage of drinking plain water opposed to drinking kilojoule liquids."
Of all liquid kilojoules, Salis believes alcohol is the worst.
"Not only does it lead to passive overconsumption where your body can’t see the kilojoules in terms of feeling satisfied, but the alcohol has an effect of stimulating food intake, making you eat more than if you hadn't drunk alcohol," Salis said.
Drinking water is also essential for good health in general.
"We do know that drinking adequate water or fluids is really important for so many aspects of health -- digestive health, body temperature regulation and so on," Salis said. "If you are hesitant about drinking water then I think this research, as well as the known health benefits, could be an extra incentive."
Of course, it goes without saying that drinking water doesn't replace healthy eating and regular exercise in helping to manage weight.
"Exercise is such an important element of weight management, combined with sensible dietary choices," Salis said.
Do you struggle to drink enough water? Try these tips on how to stay hydrated.