Continuous monitoring of Blood Pressure (BP) is desirable in the management of cardiovascular disease (CVD). Novel tools are exploring Photoplethysmography (PPG) to determine a patient BP. We utilized a Monte Carlo (MC) framework to connect the cardiovascular biomechanics and light transport associated with a PPG signal. Optical properties specific of obese and non-obese groups were used to determine their influence on the PPG waveform. Our simulation shows that the PPG signal is altered in individuals suffering from obesity, which could limit their use in BP monitoring.