Does drinking water before meals really help you lose weight?
If you've attempted to lose extra weight, you've likely encountered the suggestion to increase your water intake. Specifically, you might have been advised to drink a full glass of water before every meal.
The latter recommendation sounds like a sensible strategy, doesn't it?
By consuming water before eating, you may feel fuller and thus eat less. But did this tactic prove effective for you? Could regularly drinking more water throughout the day yield similar results? Why is it commonly believed that drinking water aids in weight loss — and what do studies reveal about its efficacy?
Three top theories are:
Feel full, eat less: As mentioned, drinking water before meals holds intuitive appeal. Within the stomach, some nerves detect stretching and subsequently send signals to the brain indicating that it's time to cease eating. Drinking before a meal could trigger similar signals.
- Evidence: Several small, short-term studies offer support for this notion. For instance, older individuals who consumed a full glass of water before meals tended to eat less than those who didn't. Another study observed that individuals on a low-calorie diet who drank additional water before meals experienced reduced appetite and greater weight loss over 12 weeks compared to those who didn't drink extra water. However, neither study evaluated the effects of increased water intake on long-term weight loss.
Burning off calories: The water we consume needs to be warmed up to body temperature, a process that demands energy expenditure from the body. This energy expenditure, known as thermogenesis, might counterbalance the calories consumed from meals.
- Evidence: While older studies initially suggested support for this theory, recent research has failed to find evidence that drinking water significantly burns calories. This challenges the notion that thermogenesis explains the weight loss effects of water consumption.
You're not hungry, you're thirsty: This explanation proposes that we may often mistake thirst for hunger, leading us to seek food when we're actually thirsty. In such instances, consuming calorie-free water could prevent us from consuming unnecessary calories, potentially fostering weight loss.
- Evidence: The regulation of thirst and hunger is intricate and can change throughout an individual's life. For instance, thirst sensation may decrease in older adults. However, there is a lack of compelling human studies supporting the idea that individuals misinterpret thirst as hunger or that this is the reason why drinking water could aid in weight loss.
Being well-hydrated enhances exercise performance and can prevent issues like muscle fatigue and heat exhaustion due to dehydration, particularly crucial for elite athletes in warm conditions. While hydrating before exercise is advisable for some, there's limited evidence directly linking hydration to exercise-related weight loss in most people.
Substituting high-calorie drinks with water may aid long-term weight loss by reducing overall calorie intake. However, conducting studies to directly prove this link is challenging.
Additionally, dehydration can impede fat breakdown for fuel, but evidence supporting the notion that increased water intake aids fat burning for weight loss in humans is lacking, despite some support from animal studies.
The bottom line
Some evidence does suggest this might aid weight loss, at least for some people. But those studies are mostly small or short-term, or based on animal data. Even positive studies only found modest benefits.