Aim: Transmitted through genetic inheritance and later unchanging, the ratio of 2nd and 4th fingers (2D: 4D) is related to the hormone testosterone. We aimed to investigate the correlation of this ratio to muscle mass and obesity. Material and Method: Adult patients attending the diet clinic were categorized by body type analysis, age and gender. Body mass index (BMI) was calculated from height and weight, and body analysis was completed with a Tanita (TANITA BC-418 MA III) device. Additionally patients had the index and ring fingers of both hands separately measured with the aid of digital calipers and recorded. The ratio of the values was determined and compared with the values obtained by the Tanita device. Result: Of 216 patients at the diet clinic, 168 were female and 48 were male. The measurements of individuals with 2D: 4D of both hands above 1 were compared with those of individuals with 2D: 4D of both hands below 1. Differences were observed in terms of total fat (TF), fat free mass (FFM) and fat mass (FM). While there was a positive correlation of the 2D: 4D of both hands with BMI, FM and TF; there was a negative correlation observed with FFM. Discussion: We believe the 2D: 4D may be directly related to obesity and inversely related to body muscle mass.