NEW YORK (Reuters Health) - Efforts to help obese children become more active and eat better can help reduce the amount of fatty tissue in their livers.

Known medically as nonalcoholic fatty liver disease, this condition is becoming increasingly common as the prevalence of obesity increases, Dr. Ana R. Damaso and colleagues from the Federal University of Sao Paulo in Brazil note in their report. There are currently no drugs available to reverse fatty liver disease, which can progress to cirrhosis, even among young patients, the doctors add.

They set out to determine whether a 12-week program including nutrition education and two one-hour exercise sessions per week would have any effect on fatty liver in a group of 73 obese teens.

At the study's outset, 52 percent had fatty liver disease on the right side of the organ, and 48 percent had fatty liver on the left side. After the program, the prevalence of fatty liver disease on both sides fell significantly to 29 percent.

After the intervention, obese teens had less fat surrounding their abdominal organs and, on average, their weight and body mass index (BMI) were reduced; 48 percent lost weight, while 48 percent maintained their weight and 4 percent gained weight.

One important aspect of the findings, Damaso and colleagues point out, is how common fatty liver disease is among obese adolescents. There is evidence that gradual weight loss is the best way to reduce fatty liver disease, they add, while sudden, large-scale weight loss may actually worsen liver function and lead to liver failure.

Additional studies are needed, they conclude, to investigate the long-term effectiveness of lifestyle interventions and cholesterol-lowering drugs in fighting fatty liver disease.