American men and children are getting fatter. That's the finding of a new study published by the Journal of the American Medical Association. Among women the numbers remained steady, leveling off at about one third the population.

Epidemiologist Cynthia Ogden with the U.S. Centers for Disease Control and colleagues analyzed height and weight measurements for 8,000 adults, teens and children from a national survey. Data from 1999-2000 compared with data from 2003-2004 showed about 17 percent of the children are overweight and about a third of the adults are obese, an increase of 3 percent among children and 1.5 percent among adults.

Ogden says she was surprised to find the weight gains over such a short time period. "And, I was particularly concerned about seeing the increase in children because we know that children who are overweight often become obese adults."

Ogden says factors like overeating, eating out more, consuming more sugary drinks and spending more time in front of the television or computer instead of exercising all contribute to weight gain. "The findings of this study really point to the same things we've always said, that we all need to watch what we eat and be more active."

Obesity is linked to increased health problems including diabetes and cancer.