Eating just a little bit more fiber could have a big impact in trimming the waistlines of America's young people, new research shows.

Latino adolescents and teens who increased their fiber intake over a two-year period had significant decreases in the amount of fat around their waists, while young people whose fiber intake fell saw their bellies expand, Dr. Jaimie N. Davis of the Keck School of Medicine at the University of Southern California in Los Angeles and her colleagues found.

Davis and her team were looking at belly fat, which is the most dangerous type of body fat. Fatter waistlines increase the risk of diabetes and heart disease.

The investigators had 85 overweight boys and girls 11 to 17 years old fill out a questionnaire on their eating habits, and then report on their diet again two years later. At this stage of life, Davis noted in an interview, the diets of some young people tend to get worse.

Fiber intake fell by 3 grams per 1,000 calories consumed, on average, for 46 of the study participants, while it increased by the same average amount for the remaining 35.

Belly fat increased 21 percent for the study participants who were eating less fiber, but the young people who upped their fiber intake had a 4 percent reduction in belly fat.

The study findings appear in the American Journal of Clinical Nutrition.

Even slight decreases in dietary fiber are having a pretty significant metabolic impact, Davis noted in an interview. The recommended fiber intake for young people, she added, is 14 grams per 1,000 calories consumed, or about 25 to 30 grams daily.

Based on the current findings, Davis noted, increasing fiber intake by six grams a day -- the amount found in half a cup of beans or a single whole-wheat tortilla -- could have a significant impact on young people's belly fat. That's not an unrealistic goal for kids to set, she said.

People of any age who want to boost their fiber intake need to take a careful look at food labels, Davis added. Just because it says 'whole wheat' or 'multigrain' doesn't mean it's a good source of fiber, she explained. People think if it's brown, if it's wheat, it's good, but not necessarily.

Instead, she advised, people should check the Nutrition Facts label to see how many grams of fiber per serving the food actually contains.

Davis said she wasn't sure that the results of her study would apply to young people from other ethnic backgrounds, given that Latino individuals may be more likely to carry fat around their waistlines than white or black people.

I do believe that increasing fiber in all cultures would have an impact, it just might have a different impact, she said.

SOURCE: American Journal of Clinical Nutrition, November 2009.