This work presents investigations on intraday variations in arterial stiffness. For this purpose, an in-vivo study was conducted on five subjects over a duration of five consecutive days. Five stiffness index ($\beta $) measurements were obtained per day for each individual. Our clinically validated ARTSENS device was used to perform fully automated reliable stiffness measurements on the carotid artery. For each measurement, two trials were performed and averaged. These trials were observed to be repeatable with the coefficient of variation $< 0.72$%. For each day, one measurement that was performed immediately after the lunch was subject to intervention due to the consumed food, which significantly $( \mathrm {p}< 0.001)$ deviated from the mean baseline $\beta $ of the day. Such significant deviations were not observed for the rest measurements that were performed in the absence of an intervention. Two subjects who consumed caffeinated beverages during the lunch exhibited an increment in $\beta $ measurement (taken immediately after lunch) as compared to mean baseline $\beta $ of the day. Further, there was no significant (p $=$ 0.97) difference between the mean baseline $\beta $ measured over a day and the mean baseline $\beta $ measured over the entire course of the study. Results obtained from the present study demonstrated that the arterial stiffness does not vary significantly over a short period but varies progressively. However, significant temporary variations in stiffness could be observed due to dietary interventions.