Two new reports from researchers at the U.S. Department of Agriculture Human Nutrition Research Center on Aging (HNRCA) at Tufts University in Boston, Mass., show little change in fast food portion sizes and product formulation between 1996 and 2013.
Led by Alice H. Lichtenstein, director of the Cardiovascular Nutrition Laboratory at HNRCA, the researchers analyzed the calorie, sodium, saturated fat and trans fat content of popular menu items served at three national fast-food chains between 1996 and 2013.
They found that average calories, sodium and saturated fat stayed relatively constant, albeit at high levels. The exception was a consistent decline in the trans fat of french fries. The studies were published Dec. 31 in Preventing Chronic Disease, a journal of the Centers for Disease Control & Prevention.
"There is a perception that restaurants have significantly expanded their portion sizes over the years, but the fast food we assessed does not appear to be part of that trend," said Lichtenstein, who is also the Stanley N. Gershoff professor at the Friedman School of Nutrition Science and Policy at Tufts. "Our analysis indicates relative consistency in the quantities of calories, saturated fat and sodium. However, the variability among chains is considerable and the levels are high for most of the individual menu items assessed, particularly for items frequently sold together as a meal, pushing the limits of what we should be eating to maintain a healthy weight and sodium intake.
"For example, among the three chains, calories in a large cheeseburger meal, with fries and a regular cola beverage, ranged from 1,144 to 1,757 over the years and among restaurants, representing 57-88% of the approximately 2,000 calories most people should eat per day," Lichtenstein added. "That does not leave much wiggle room for the rest of the day."
According to the authors' 2013 data, calorie content of the cheeseburger meal among the three chains represented 65-80% of a 2,000-calorie-per-day diet and sodium content represented 63-91% of the recommendation.
Lichtenstein and colleagues focused on the four most popular menu items: fries, cheeseburgers, grilled chicken sandwiches and regular cola, looking for trends in portion size and nutrient content over an 18 year period. They examined 27 items including small, medium and large fries and cola beverages, a grilled chicken sandwich and 2 oz. and 4 oz. cheeseburgers. The authors used a public database and the internet to access archived nutrition data.
They found only small fluctuations in calorie content and the amount of saturated fat and sodium. The notable exception was fries, which decreased first in saturated fat in 2001 and then trans fat, likely due to changes to the frying fat.
"The decline in trans fat we saw between 2005 and 2009 appears to be related to legislative efforts," Lichtenstein said. "The success of New York City's trans fat ban and others like it, suggest it is worth pursuing these types of approaches because they make the default option the healthier option. Of course, it is important to note that the healthier option in terms of fat does not translate into lower calories or less salt."
The authors also note nutrient content varied among similar items from different chains. For example, an order of small fries could differ by as much as 110 calories and 320 mg of sodium from chain to chain.
"For this reason, our findings strongly suggest that public health efforts promoting reduction of calories and over-consumed nutrients need to shift from emphasizing small, medium and large portion sizes, to additional factors such as actual number of calories and the nutrient content of the items, as is increasingly becoming available at point of purchase," Lichtenstein said. "A 100 calorie difference per day can mean about a 10 lb. weight change per year."