A survey of 2,000 employees found that tradespeople were the most active, averaging seven hours of physical exertion every day.
They burn on average 2,500 calories a day during work, compared to IT workers who are on average active for just 24 minutes a day and get rid of fewer than 200 calories.
The survey, by IronmongeryDirect, found that tradespeople even beat personal trainers and health and fitness professionals, who are physically mobile for five hours a day.
Farm workers also came out as one the fittest professions with more than four hours of exertion during their shift.
Joining IT workers in the unhealthy league were marketing staff, who burned off 36 minutes of energy, and lawyers and accountants, active for just 42 minutes a day.
Builder Tony Brookes, 34, of Hastings, East Sussex, said: “I do an eight or nine-hour day and I’m active the entire time.
“That’s why I need a couple of bacon sandwiches in the morning and a big lunch otherwise I’d collapse.”