In this paper, we propose a health support system «WaistonBelt 2,» which consists of a belt-type wearable device and a smartphone application. Our system aims to support users to obesity (the metabolic syndrome) that may lead to various adult diseases such as arteriosclerosis, heart disease or stroke. Our proposed device can automatically measure a circumference on the belt position when a user wears it by a rotary encoder, and monitor a tension of belt for recognizing posture and overeating. The measured data is transmitted to our application via Bluetooth. Stored values are visualized by graphs, and advices are given through the avatar based on the analyzed data. Through evaluation experiments, we confirmed that our proposed device achieves highly accurate measurement of the circumference on the belt position (average absolute error is 0.73 cm). We also confirmed that it is possible to realize a recognition system of posture and eating action using belt pressure sensing system.