Despite obesity leveling off across the United States for the first time in years, "extreme obesity" in children and adults has been on the rise, Reuters reported.

In Trust for America's Health and the Robert Wood Johnson Foundation' annual report "F is for Fat," researchers found the percentage of adults who are at least 100 pounds overweight has more than quadrupled in last three decades. In the 70s, that level was 1.4 percent and in 2009-10, it was 6.3 percent.

Five percent of children were reported being extremely obese. Rates among women were nearly double that of men and was worst among Hispanic boys and black girls.

"As long as we continue to see those increases in extreme obesity, I think we need to be worried," Trust for America's Health Executive Director Jeffrey Levi told Reuters.

Another recent health study found obesity levels to either level off or decrease in 49 states, with Arkansas being the only to report an increase. Also in decline are obesity rates among children in low-income families, down for the first time in 30 years of increasing.

"After decades of bad news, we're finally seeing signs of progress," the study's authors wrote Friday.

The researchers used data from the Centers for Disease Control and Prevention, which found Southern and Midwest states to have the worst obesity rates. Even those states recently reported declines.

"I'm delighted but not surprised," said Kelly Brownell, dean of Sanford School of Public Policy at Duke University. "The collective effect is having an impact and turning things around... We've managed the plateau, we may remain there. We will have to do more to achieve a downturn."

Health experts agreed many government programs and other initiatives are starting to prove they are working. From various grade schools making children's lunch options healthier, restaurants posting calorie counts and even First Lady Michele Obama's "Let's Move!" initiative, efforts have been paying off.

The report confirmed what the previous study did as well, whatever has been working to lower obesity, keep doing it.