Fast food has become ubiquitous in the American diet, with over 25% of Americans eating fast food two or more times a week.

Investigators examined food trends and nutrition profiles of menus from eight popular fast food chains between the years of 1997 and 2010.

Researchers evaluated the nutritional quality of the restaurants' offerings using the U. S. Department of Agriculture's Healthy Eating Index 100-point scale.

Disappointingly, the results showed the nutritional quality of fast food improved only by three points from 45 to 48 over the study period.

Compared to prior years, scores remained unchanged for fruits, vegetables, grains and oils, but improved for calories from solid fats and added sugars as well as meat and saturated fat levels.

A handful of the restaurants did improve their individual scores by offering more proteins and grain options and lowering sugar and saturated fat levels.

Scores were worse for dairy and sodium.

However, a 14-year study published in the American Journal of Preventive Medicine shows menus haven't made much improvement in their nutritional quality.

With Americans consuming about one-third of their calories outside the home, fast food is playing a greater role in how families feed themselves.

Margo Wootan, the director of nutrition policy at the Center for Science in the Public Interest in Washington, D. C, said in her commentary, "The full impact of menu labeling will not be clear until menu labeling is implemented nationally and consumers become accustomed to seeing calorie counts on menus".

But public health advocates remain hopeful that restaurants will start to take greater responsibility for offering healthier foods, since their current offerings may be contributing to health problems related to diet, like diabetes and obesity. Thank you.

However, other restaurants headed in the other direction by boosting sodium and saturated fats.

Large restaurant chains have started displaying calories counts on their menu boards, and smaller chains should follow suit.