We have used the finite-difference time-domain method to calculate the distributions of absorbed energy for a 1.34 x 1.34 x 1.4 cm resolution anatomically based model of the human body for exposure to leakage electromagnetic fields of a radiofrequency dielectric heater operating at 40.68 MHz. To simulate workplace conditions, the dielectric heater is assumed to be placed in a screen room and different operator postures, such as standing or sitting on a wooden or metal stool with hands on sides or extended toward the radiofrequency heater, are considered. To obviate the problem of having to model a fairly large volume of the screen room of assumed dimensions 2.13 x 3.05 x 2.13 m, we have used a uniform finer grid of points for the finite-difference time-domain method for the closely coupled region consisting of the front region of the heater and the human model, while a newly developed expanding-grid finite-difference time-domain formulation is used elsewhere. This results in a saving of both the memory and computation times by almost a factor of four. The average rates of energy absorption are given for the whole body, selected parts of the body, and various organs. As expected, the foot currents and the rates of energy absorption are higher with the screen room for sitting postures where the upper parts of the body are in higher electromagnetic fields, and for hands extended toward the heater.