By Katty Kay
BBC News correspondent in Washington
Obesity costs American companies some $13bn (£7bn) a year
If there is a lift to take you up to your office every day are you really going to choose the stairs?
Perhaps architects can help you decide by designing fat-fighting buildings which simply force you to walk more.
In the heart of suburban Kansas is an oasis of corporate fitness.
Telecom giant Sprint designed its 200-acre headquarters to make employees lose weight by forcing them to walk everywhere.
The motive: obesity now costs American companies some $13bn (£7bn) a year.
'We lost 83kg'
Sprint employees Ed and Mary still drive 16km (10 miles) to work, but the rest of the day they walk.
Between them they have lost 83kg (182lbs), and they credit the layout of the campus.
"I don't ever take the elevators," says Mary.
"I have my computer case, my bags, all that and I'm walking up three flights of stairs every day just because I want that."
Ed adds: "Now I can get through a day, I'm not fatigued, I'm not stressed, my energy levels are much stronger and I feel I'm more productive."
Sprint built the car parks a 10-minute walk from the office buildings.
Inside, Sprint asked the architects to make the staircases airy and inviting.
The company wants people to use them, so by contrast it has made the lifts slow and small.
But not everyone appreciates the enforced fitness regime.
"Walking over from the parking garage sucks," said one disgruntled employee.
"It's not bad," says another, "unless it's 110 degrees outside or below freezing and raining and cold."
Sprint vice-president Faye Davis says the grumbling is inevitable when you change people's habits.
Anyway making its workforce healthier is a battle the company cannot afford to lose.
"If you're overweight, you probably have a higher level of absenteeism or you get more fatigued during the day, perhaps you have a lower concentration span," says Ms Davis.
"We all know when we do exercise we have a higher energy level, we're more focused and we're not sick as often," she adds.
Sprint says this experiment shows that if you give employees a nudge, they will take more exercise and so lose weight.
It is good for company profits and for the health of the staff, of course.
The problem is, this is an exception.
Most office buildings in America simply give people the easy way out.
We took Sprint's architect Phil Dordai on a tour of a traditional office block in Washington DC to see how it fared in the fat test.
How did it rank as a fitness-friendly building?
Well, not very good.
"There's actually the three lifts here and no way to find the stairs," he comments.
How important is it for architects to help in the obesity battle?
"I think it's hugely important because none of us has much time in the course of the day to exercise, so if you can incorporate exercise and physical activity as part of your normal day where you work, that's very advantageous."
Back in Kansas, Sprint's campus is surrounded by six-lane highways.
In a culture where the car is king architecture can only do so much.
The challenge nationwide is to get Americans back on their feet.