So why do construction workers who are more active still have obesity?

You'd need a wider sample of sedentary office workers than just sales and marketing to make that conclusion.

Okay I finally found the article. https://www.theatlantic.com/health/archive/2014/03/the-jobs-...

I'd say the physically active jobs are actually on the middle to upper half of the list. Transportation, warehousing, manufacturing and construction for example.