As lifestyles become more hectic, fast foods feature more frequently in the daily American diet. The latest national figures for 2007-2010 show that on average, adults in the US get more than 11% of their daily calories from eating fast food. Although this is lower than the nearly 13% of a few years earlier, federal officials say it does not necessarily indicate a downward trend.

Researchers from the US Centers for Disease Control and Prevention (CDC), published their findings online in a National Center for Health Statistics (NCHS) data brief on Thursday.

After examining data from the National Health and Nutrition Examination Survey (NHANES), they found that during 2007 to 2010 US adults on average consumed 11.3% of their total daily calories from fast foods, such as pizzas and burgers bought in chain restaurants. This compares with 12.8% for 2003-2006.

NHANES is a program of studies designed to assess the health and diet of American adults and children through physical exams and interviews. One of the interview questions asks participants to recall where they got the food they’d eaten in the previous 24 hours. The researchers counted responses like “restaurant fast food/pizza” as fast food.

The researchers found that the proportion of fast food in the American diet rapidly fell with age, in both men and women, with adults aged 60 and over consuming the lowest percentage (6.0%) of their daily calories from fast foods.

There was little significant difference between men (11.8%) and women (10.9%).

There were, however, racial differences. For instance, non-Hispanic black adults got more of their calories from fast foods than non-Hispanic white and Hispanic adults.

And among young non-Hispanic black adults aged 20 to 39, more than one-fifth (21.1%) of their calories were consumed from fast food.

Across income groups, the percentage of daily diet that came from fast foods was the same: of all adults, the wealthier ones got as many of their daily calories this way as poorer ones.

However, when they looked at young adults only, the researchers found there were disparities by income group: the wealthier ones consumed less of their daily calories as fast food than poorer ones.

They also found that the proportion of calories from fast food went up with weight, with obese adults getting more of their daily calories from fast food than normal weight adults. The largest figures were for obese adults aged 20 to 39, for whom 18.0% of their daily calories came from fast food.

More than one third of adults in the US are obese, and the authors note that frequent fast-food consumption has been shown to contribute to weight gain.

In January 2013, the Center for Science in the Public Interest (CSPI) published their Xtreme Eating 2013 list, that shows many major restaurant chains across the US serve meals that have calorie counts far exceeding the daily recommended amounts.

Michael F. Jacobson, executive director of CSPI, said some restaurant chains “are scientifically engineering these extreme meals with the express purpose of promoting obesity, diabetes, and heart disease“.

Written by Catharine Paddock PhD