Effect of intentional daily liter of plain water on total fluid and caloric intake among free-living adults

Abstract

While previous studies have examined short-term water consumption and corresponding energy intake, few have investigated the effects of a longitudinal intervention in non-obese, young adults. We aimed to evaluate the effect of a 6-week daily liter of plain water consumption on fluid and caloric intake among free-living healthy adults. Thirty-eight young healthy adults (25 ± 6 y, 1.67 ± 0.09 m, 73.0 ± 16.7 kg, 25.8 ± 4.2 of body mass index) were provided two 500mL bottles of water per day and asked to consume them for six weeks. They were provided no further direction on fluid consumption during the study. Participants recorded 24-hour total food and fluids consumed and collected urine across three time points of baseline, 3-week (mid), and 6-week (post). Twenty-four-hour total fluid, plain water, sugar-sweetened beverages, caloric intake, urine specific gravity (USG), urine osmolality (U osm ), and urine volume were measured at all three time points. Hydration status was assessed via 24-hour USG and U osm . Twenty-four-hour total fluid intake was significantly increased at mid (p = .040) but not post (p = .426). Twenty-four-hour total plain water intake was significantly increased at mid (p = .028) and post (p = .049) time points. No significant differences were observed in 24-hour total sugar-sweetened beverage intake across time points (p = .210). Twenty-four-hour total caloric intake was significant reduced at the post (p = .048) but not at mid (p = .257). Twenty-four-hour total caloric intake was not associated with 24-hour total fluid intake (r = .052, p = .618), total plain water intake (r = −.049, p = .636), and total sugar-sweetened beverages intake (r = .143, p = .170). No significant differences were found in 24-hour USG (p = .075) and total urine volume (p = .491) among time points, but U osm significantly decreased at mid (p = .001). In conclusion, a moderate increase in plain water intake may prompt a decrease in daily caloric intake and thus facilitate weight management.