Tufts University

Children are eating less frequently at fast-food restaurants and consuming fewer calories from burgers, pizza and chicken sold at the outlets, say two researchers from Tufts and the University of Washington.

Consumption of healthy foods such as fruits and vegetables improved worldwide over the two decades ending in 2010, but "intake of unhealthy foods including processed meat and sweetened drinks" rose more rapidly, according to a study published in the journal Lancet Global Health.

Forget about super-sizing. Portion size at three major fast-food chains changed little from 1996-2013, say researchers at Tufts. In a pair of reports, they say sodium, fat and calorie totals "stayed relatively constant albeit at high levels," according to a Tufts release.

The panel writing the new edition of the Dietary Guidelines for Americans - the government's tips for healthy eating - is wading into the question of food systems sustainability.