Both lean and fat body mass associate with blood pressure.

High body mass index (BMI) is known to be associated with elevated blood pressure (BP). The present study aims to determine the relative importance of the two components of BMI, fat mass and lean body mass index, on BP levels. We assessed body composition with bioimpedance and performed 24 hour ambulatory BP measurements in 534 individuals (mean age 61 ± 3 years) who had no cardiovascular medication. Fat mass index and lean mass index were calculated analogously to BMI as fat mass or lean body mass (kg) divided by the square of height (m2). Both fat mass index and lean mass index showed a positive, small to moderate relationship with all 24 hour BP components independently of age, sex, smoking, and leisure-time physical activity. There were no interaction effects between fat mass index and lean mass index on the mean BP levels. Adult lean body mass is a significant determinant of BP levels with an equal, albeit small to moderate magnitude as fat mass. Relatively high amount of muscle mass may not be beneficial to cardiovascular health.