It's no secret that the food on offer today at most fast food joints are unhealthy and spurs the obesity epidemic, particularly among children. Now new research looked at all the possible combinations of main dishes, sides and drinks - for a total of 5,427 possible meals and found that only 33 were considered healthy.

Analysts from the Yale Rudd Center for Food Policy and Obesity - a leading proponent of efforts to remove sugary drinks from schools and impose a sin tax on sodas - examined the menu offerings from 18 fast-food chains. The team measured the caloric intake of all potential food combinations of main dishes, sides and a drink - and only a 3 percent of those on offer met the nutrition guidelines.

"There were some improvements, but they have been small, and the pace too slow," said Marlene Schwartz, Rudd Center director. "Without more significant changes, we are unlikely to see meaningful reductions in unhealthy fast food consumption by young people."

In the report, "Fast Food FACTS 2013," the researchers noted the fast food industry spent $4.6 billion in 2012 to advertise mostly unhealthy products, and children and teens remained key audiences for that advertising.

 "Most fast food restaurants stepped up advertising to children and teens," said Jennifer Harris, the Rudd Center's director of marketing initiatives and lead author of the report. "Most advertising promotes unhealthy regular menu items and often takes unfair advantage of young people's vulnerability to marketing, making it even tougher for parents to raise healthy children."

According to the report, on days that include at least one visit to a fast food restaurant, children on average consume 126 more calories while teenagers consume 310 more calories per day.

Other key findings include:

  • Children ages 6 to 11 saw 10% fewer TV ads for fast food, but children and teens continued to see three to five fast food ads on TV every day;
  • Healthier kids' meals were advertised by a few restaurants, but they represent only one-quarter of fast-food ads viewed by children;
  • Less than 1% of kids' meals combinations at restaurants meet nutrition standards recommended by experts, and just 3% meet the industry's own Children's Food and Beverage Advertising Initiative and Kids LiveWell nutrition standards;
  • Spanish-language advertising to Hispanic preschoolers, a population at high risk for obesity, increased by 16%;
  • Fast food marketing via social media and mobile devices - media that are popular with teens - grew exponentially.

The report was supported by a grant from the Robert Wood Johnson Foundation.