Using a population model and other data, a new report released on Tuesday by the Trust for America's Health and the Robert Wood Johnson Foundation predicts that half of U.S. adults will be obese by 2030 unless people change their ways.

The "F as in Fat" report highlights the current glum picture of the U.S. obesity epidemic, in which 35.7 percent of adults and 16.9 percent of children age 2 to 19 are obese, as the Centers for Disease Control and Prevention (CDC) reported earlier this year.

But for the first time, the report builds on state-by-state data from the CDC to project obesity rates. In every state, that rate will reach at least 44 percent by 2030. Iowa's adult obesity rate will nearly double, with a predicted obesity rate of over 54 percent. In 2011, Iowa's obesity rate was 29 percent.

Obesity raises the risk of numerous diseases, from type 2 diabetes to endometrial cancer, meaning more sick people and higher medical costs in the future. It projects as many as 7.9 million new cases of diabetes a year, compared with 1.9 million new cases in recent years. There could also be 6.8 million new cases of chronic heart disease and stroke every year, compared with 1.3 million new cases a year now.

The new projection supports a study published earlier this year in the American Journal of Preventive Medicine that found that by 2030, 42 percent of U.S. adults could be obese, adding $550 billion to healthcare costs over that period.

Sources: MSNBC, Reuters, CDC, Robert Wood Johnson Foundation