In today's world obesity is one of the most serious public health challenges as it is linked to an increased risk of heart disease, high blood pressure, diabetes, and other chronic conditions. The key point to study obesity epidemic is to measure the amount of fat in the human body. Bioelectrical impedance analysis (BIA) is a noninvasive method widely used for estimating fat mass. In a typical BIA, a small amount of alternating electrical current is applied to the human body and the body impedance is measured. Commercial systems used for BIA nowadays are typically large, bulky, and can be very expensive. In this paper, we present a novel wearable bioelectrical impedance analyzer for body fat estimation. The designed analyzer consists of a ring based wearable sensing system and a microcontroller module which also provides wireless connectivity via Bluetooth. An android based application was also developed to provide a smartphone interface for the users to track and manage their health data. The fat mass estimation using the designed analyzer was compared with the commercially available OMRON body fat monitor for 40 healthy human subjects. A linear regression demonstrates a strong correlation between the designed device and the reference monitor with a correlation coefficient r = 0.9. Furthermore, 38 out of 40 subjects lie within 95% limit of the agreement which shows that the designed body fat analyzer has comparable performance with the reference monitor.