With the advent of high precision sensors and Internet of Things (IoT) enabled medical devices, healthcare has seen a gradual decentralization from the traditional health center based approach. These smaller form factor IoT healthcare devices have reduced the cost of healthcare leading to affordability and wider adoption. This paper enunciates recent advances in the architecture as well as system design of IoT based healthcare systems. Healthcare systems like mHealth and 6LoWPAN based architectures are explored. Healthcare systems involving IEEE 11073 and Constrained Application Protocol (CoAP) are described. Multisensor based system designs that sense blood glucose, body temperature, heart rate and electrical activity (ECG) etc. are explored. The paper provides a comprehensive survey of recent advances in IoT based healthcare system and proposes Intel Curie based healthcare system design.