Moderate coffee intake does not significantly affect short-term bioelectrical impedance measurements in healthy women

NUTRITION RESEARCH, vol.150, pp.62-71, 2026 (SCI-Expanded)

Bioelectrical impedance analysis (BIA) is a widely used, noninvasive method for assess-

ing body composition. However, its sensitivity to acute changes in water consumption and

coffee intake raises concerns about measurement reliability. This study hypothesized that

the short-term consumption of 200 mL caffeinated or decaffeinated coffee would result in

measurable changes in BIA-derived body composition parameters compared to water in-

take. Twenty-seven healthy female participants (aged 18-35 years; body mass index 18.5-

29.9kg/m²)wererandomlyassignedtooneofthreegroups:caffeinatedcoffee,decaffeinated

coffee, or water (n = 9 per group). After all groups consumed 200 mL of the assigned bever-

age, BIA measurements were performed at baseline, 30, 60, 90, and 120 minutes using the

InBody 270 analyzer. Nonparametric tests (Kruskal–Wallis, Friedman) and Quade ANCOVA

were applied to assess between- and within-group differences, adjusting for baseline val-

ues. Significant within-group changes were observed in body weight and body mass index

across all groups (P < .05). Between-group differences emerged in fat mass, fat percentage,

and body mass index at multiple time points (P < .05); however, none remained significant

after adjusting for baseline using Quade ANCOVA (all P > .05). Notably, several parameters

showedmediumtolargeeffectsizes,despitenonsignificantP values.Undercontrolledcon-

ditions, moderate caffeine intake (∼95 to 100 mg) or 200 mL fluid volume does not induce

significant short-term alterations in BIA-derived body composition in healthy women. Vi-

sual trends suggest transient fluctuations within the first 60 minutes, though these were

not clinically meaningful.