The expanding girth of Americans is no secret — First Lady Michelle Obama is spearheading a national campaign against obesity. Now the Federal Transit Authority is responding to the issue by rewriting bus safety rules regarding passenger weight.

The FTA has proposed raising the assumed weight per bus passenger from 150 pounds to 175 pounds, according to a story in USA Today. That means fewer people will be allowed to ride a city transit bus. The agency also wants to add more floor space per passenger in bus designs.

The plans, the agency says, are being developed "to acknowledge the expanding girth of the average passenger." Transportation experts say they are needed.

"This change is really just a bow to reality," Joseph Schwieterman, who studies bus ridership as director of the Chaddick Institute for Metropolitan Development at DePaul University in Chicago, tells USA Today. "With no small number of bus passengers tipping the scale at 200 pounds or more, this is much more realistic."

To read the full USA Today story, go here now.