(44) ACUTE WATER INGESTION DOES NOT INFLUENCE PERCENT BODY FAT USING BIOELECTRICAL IMPEDANCE ANALYSIS

Thursday, July 11, 2024

12:00 PM – 1:30 PM East Coast USA Time

Location: Exhibit Hall

Poster Presenter(s)

Tina E. Sergi, MS, RD, CSCS

Assistant Chief, Nutrition Education and Research
Walter Reed National Military Medical Center
North Bethesda, Maryland, United States

Author(s)

GL

Gangwoo Lee

NCOIC, Nutrition Education and Research
Walter Reed National Military Medical Center
Rockville, Maryland, United States
Jeffery L. Heileson, PhD (he/him/his)

Chief, Nutrition Education and Research
Walter Reed National Military Medical Center
Arlington, Virginia, United States

Abstract Details: The rising rates of overweight and obesity among military personnel is a concern, especially since Soldiers are required to be physically fit to ensure that they can perform their occupational duties and meet mission requirements. The Army has authorized the use of multi-frequency bioelectrical impedance analysis (MF-BIA) as a supplemental body fat assessment for Soldiers who do not meet height and weight standards and fail the circumference-based tape test. While MF-BIA can provide valuable information, including (LBM), fat mass (FM), body fat percentage (%BF), and total body water (TBW), external factors such as fluid intake may influence body composition parameters. For military personnel, the accuracy of supplemental body fat assessments is especially important, as failing body composition standards could negatively impact or end a service member’s career. Despite this, standardization of water ingestion prior to MF-BIA has yet to be established.

Purpose: 1) Determine the change in body composition estimates (BCE) following water intake and 2) explore the relationship between relative acute water ingestion (ml·kg^-1) and BCE.

Methods: Eleven healthy, active-duty military personnel (n = 5 male, n = 6 female; age 32.5 ± 8.3 years; bodyweight [BW] 75.3 ± 11.8 kg; LBM 31.0 ± 8.3 kg; FM 17.3 ± 6.5 kg; %BF 23.2 ± 8.4%; TBW 42.4 ± 8.4 kg) were randomized to a water intake group (250 mL, 500 mL, or 1000 mL). Body composition assessments via MF-BIA were conducted at baseline (PRE) and 60 minutes (P60) after water consumption. Water consumption was normalized to body weight (ml·kg^-1) for all analyses. The change in body composition parameters (PRE to P60) were determined via paired-samples t-test. A linear regression analysis examined the relationship between acute water ingestion, normalized to body weight (ml·kg^-1), on BCE. An alpha level of ≤ 0.05 was used to determine statistical significance.

Results: On average, participants ingested approximately 8.0 ml·kg^-1 of water. Water intake significantly increased BW (+0.4 ± 0.4 kg; p = .002) and FM (+0.6 ± 0.6 kg; p = .009) between PRE and P60. Of note, there was a non-significant increase in %BF (+0.6 ± 0.9%; p = .057). Lean body mass and TBW were not significantly different between PRE and P60. Based on the linear regression model, relative acute water intake did not significantly predict changes in %BF (F[1,9] = .229, p = .664) or LBM (F[1,9] = 3.342, p = .101).

Conclusions: Acute water ingestion significantly increases BW and FM; however, no significant changes in %BF, LBM, or TBW were detected. Furthermore, relative acute water ingestion was not a significant predictor of changes in LBM or %BF in healthy, active-duty service members. PRACTICAL APPLICATIONS: Consuming 8.0 ml·kg^-1 of water does not seem to negatively impact body composition in our sample of healthy, active-duty military personnel. For military personnel near the %BF cut-offs, any increase, from water intake or standard device error, can be concerning, since %BF is the only body composition parameter that the military uses for retention. Future research, especially with an adequate sample size, is needed to determine if ingesting an amount greater than 8.0 ml·kg^-1 may negatively influence BCE.

Acknowledgements: None