The ACSM American Fitness Index is a scientific snapshot of health and fitness at a metropolitan level. On a national level, San Jose ranked at the #6 healthiest city. San Francisco came in a hair better at #5.
The areas San Jose excelled at include a high vegetable consumption, low percentage of people smoking, low obesity rates, high percentage of people in excellent or very good health, and a high number of playgrounds and parks per capita. Areas improvement include a higher percentage of mental health issues (all the stress from tech jobs?) and a higher rate of asthma than other metros.
You can download the full report as well as historic reports at the link below.
Source: ACSM American Fitness Index, Hat tip to Barclay Livker