(P06-020-24) Associations Between Habitual Fluid Intake and Energy Balance in Young Adult Males

Objectives: Chronic positive energy balance, where energy intake exceeds energy expenditure, is the primary contributor to obesity. Previous studies have linked low fluid intake to obesity, but none have directly assessed relationships between fluid intake and each component of energy balance (EB). This study explored associations between habitual total fluid intake (TFI) and components of EB, including total daily energy expenditure (TDEE), resting metabolic rate (RMR), thermic effect of food (TEF), physical activity energy expenditure (PAEE) and energy intake (EI).

Methods: Twenty-seven male participants (age, 23 ± 4y; height, 176 ± 6.5cm; body mass, 78.8 ± 13.0kg; body fat,17.2 ± 9.0%) completed RMR and 3-hour TEF assessments prior to and following a standard breakfast, respectively. Participants self-reported food and fluid intake to determine EI and TFI and wore an activity monitor to assess PAEE for 3 days preceding and for 3 days following the laboratory visit. Linear regressions were used to assess relationships between mean TFI and RMR, TEF, and the respiratory exchange ratio (RER) for each measure. Separate linear mixed models assessed day-to-day associations of within- and between-person differences in TFI on EI, PAEE, and EB (EI - TDEE).

Results: Greater mean TFI was associated with higher RMR (β = 69.4 kcals, [22.52, 116.24], p = 0.008) and lower average RER throughout TEF measures (β = -0.02, [-0.03, -0.01], p = 0.008). Greater TFI between participants was associated with greater PAEE (β_bsPAEE = 211.50, [72.22, 350.79], p = 0.003) but also greater EI (β_bsEI = 193.87 kcals, [43.74, 344.01], p = 0.012). However, neither within-person nor between person differences in TFI were associated with EB (p > 0.05).

Conclusions: Greater TFI was associated with higher RMR and greater post-prandial fat oxidation, suggesting greater fluid intake could be utilized as a potential effective strategy for weight management. Associations between increased PAEE and both TFI and EI may suggest individuals with greater total fluid intake are able to adequately meet the recovery demands of increased physical activity through the provision of both additional fluid and energy intake.

Funding Sources: This study was supported in part by Adams Sports Medicine Consulting, LLC and Emerja Corporation.