The people down at the "local boozer" probably don't talk about BMI because either....
A: They don't work out or attempt living a healthy lifestyle, so BMI does not become something for them to think about.
or
B: They're too drunk to understand/care about the concept of BMI
A: They don't work out or attempt living a healthy lifestyle, so BMI does not become something for them to think about.
or
B: They're too drunk to understand/care about the concept of BMI