In the quest for weight loss, the belief that drinking ample water is a magic solution is widespread, with some suggesting consuming a gallon a day. However, scientific evidence does not strongly support these claims. While a small study showed a brief boost in calorie expenditure after drinking water, the net increase is minimal, even with increased intake. Additionally, water’s ability to reduce appetite varies across age groups, with mixed results in weight loss studies. Water alone is not an effective appetite suppressant, but when combined with substances like fiber or soups, it may delay stomach emptying, potentially aiding in feeling fuller longer. Nevertheless, swapping calorie-rich drinks for water can help cut daily caloric intake, potentially assisting in weight loss.
Source: https://theconversation.com/weight-loss-drinking-a-gallon-of-water-a-day-probably-wont-help-you-lose-weight-211311