I do wonder how they tracked this metric. Like yeah, SF has health food places on just about every corner and it’s easy to get by without needing to have a car so most people walk if they are able to, but the people out on that street range from neo-hippy yoga bunnies to individuals permanently confined to a mobility scooter. If they are only looking up medical information for people who can afford to both live in San Francisco and go to the doctor to get things like a BMI done so that the results could be collected, then the results are probably going to be wildly skewed towards the healthy, fit, energetic techbros and other such people who are able to afford that kind of healthy lifestyle in spite of the extreme cost of living.