Quantitative MRI markers of the liver are attractive diagnostic tools of metabolic dysfunction-associated steatotic liver disease (MASLD). However, T 1 $$ {\mathrm{T}}_1 $$ measurements are confounded by physiological factors, such as hydration. The aim of this study is to evaluate the dynamic effects of hydration with isotonic drinks on quantitative MRI measurements of the liver in healthy male individuals. Shortened modified Look-Locker inversion recovery-based (shMOLLI) T 1 $$ {\mathrm{T}}_1 $$ , T 2 * $$ {{\mathrm{T}}_2}^{\ast } $$ , proton density fat fraction (PDFF), apparent diffusion coefficient (ADC), stiffness, and volume of the liver, as well as shMOLLI T 1 $$ {\mathrm{T}}_1 $$ and volume of the spleen were measured repeatedly in six healthy male volunteers at 3 T after ingesting 0.5, 1.0, and 1.5 L of isotonic drink on three different days. T 1 $$ {\mathrm{T}}_1 $$ data were fitted to a first-order linear time-invariant system model, descriptive statistics were calculated for the other parameters, and linear mixed models were employed to assess co-variates of quantitative MRI parameters. Liver T 1 $$ {\mathrm{T}}_1 $$ showed a maximum absolute increase of 58, 60, and 90 ms, while spleen T 1 $$ {\mathrm{T}}_1 $$ showed a maximum absolute increase of 45, 70, and 150 ms corresponding to 0.5, 1.0, and 1.5 L of isotonic drink, respectively. The maximum change in ADC, T 2 * $$ {{\mathrm{T}}_2}^{\ast } $$ , liver volume and spleen volume gradually increased, while that in liver stiffness gradually decreased with increasing amounts of isotonic drinks. PDFF values had no dependence on the volume of ingested isotonic drink. First-order models showed increasing time constants for both the liver and the spleen corresponding to increasing isotonic drink volumes. Liver time constants were only dependent on ingested drink volume. This study explored the effect of different volumes of isotonic drink and quantitative liver MRI markers. We found that the increase in T 1 $$ {\mathrm{T}}_1 $$ likely bears clinical significance, however, the variation observed in the other parameters need further investigation and validation in a larger cohort.