The average U.S. adult weighs significantly more today than a few decades ago, prompting the U.S. Coast Guard to implement nationwide regulations that could restrict the number of passengers allowed on board a vessel.

The new vessel-stability rules raised the estimated weight of an average adult passenger from 160 pounds to 185 pounds.

The regulation follows population data from the U.S Centers for Disease Control and Prevention suggesting a dramatic weight increase in the past two decades. An estimated one-third of U.S. adults are considered obese, according to the CDC.

The vessel-stability rules apply to any passenger vessel that carries six or more paid customers, a Coast Guard spokeswoman said.

Each vessel is inspected for stability by the Coast Guard and given a weight restriction, the spokeswoman said. The Department of Homeland Security uses an Assumed Average Weight per Person to set weight restrictions on boats based on their size and capacity.

Many ferry and charter-boat operators have begun reducing the number of passengers allowed on board.

The Coast Guard last implemented changes to the rules in 1960, when the average adult weight was between 140 and 160 pounds.