Hawaii’s 2011 adult obesity rate is the second-lowest in the nation, but that could change dramatically for the worse in 20 years, according to a report released today by two public health groups.

Hawaii ranked 50th with a 2011 obesity rate of 21.8 percent, according to the report titled, "F as in Fat: How ObesityThreatens America’s Future 2012," by Trust for America’s Health and Robert Wood Johnson Foundation. The state with the lowest rate was Colorado at 20.7 percent.

But the number of obese adults has grown dramatically in Hawaii over the past 15 years and is expected to grow even more in the next 20 years, the report said. The groups warned Hawaii’s obesity rate is projected to climb to 51.8 percent in 2030, if the Aloha State continues on its current trajectory. In 1995, Hawaii’s obesity rate was 10.6 percent.

"By 2030, obesity-related health care costs in Hawaii could climb by more than 12.3 percent, which would the 38th highest increase in the country," the report said. "In the United States, medical costs associated with treating preventable obesity-related diseases are estimated to increase by $48 billion to $66 billion per year by 2030."

This is the first time the annual report forecasts 2030 adult obesity rates.

"This study shows us two futures for America’s health," said Dr. Risa Lavizzo-Mourey, president and CEO of the Robert Wood Johnson Foundation. "At every level of government, we must pursue policies that preserve health, prevent disease and reduce health care costs. Nothing less is acceptable."

If body mass index would be reduced by 5 percent, Hawaii’s rate in 2030 would instead be 45.5 percent, the report said.

Hawaii has one of the lowest obesity rates in the nation for 10- to 17-year-olds. Hawaii tied for 46th with Iowa at 11.2 percent.