Your fast food is as fatty as ever…

Conventional wisdom says that fast food portions are growing bigger and bigger and bigger. It's also wrong. Two new reports found little change in average sodium, saturated fat and calories at three major fast-food chains.

The fast food industry has worked hard to revamp its image in recent years, with some chains adding items like egg whites, oatmeal and more salads to their menus. Despite the new items, little has really changed for many of the most popular items, according to two new reports from Tufts University's USDA Human Nutrition Research Center on Aging published in the CDC's journal Preventing Chronic Disease.

Cheeseburger
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Researchers analyzed nutritional information at three national fast food chains from 1996 to 2013 and found that average calories, sodium and saturated fat stayed at relatively constant high levels. Trans fat levels did drop overall for French fries, as legislative efforts to clamp down on that type of fat had a spillover effect on the popular side item.

They focused on the most popular and basic items at these fast food restaurants to find overall trends in the data: fries, cheeseburgers, grilled chicken and regular cola. Within these, they looked at various sized items using information from a public internet data base.

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"Although there were small changes in portion sizes and sodium, in general, there wasn't all that much of a change even though public health guidelines had recommended a decrease in calories and sodium," said Alice Lichtenstein, a professor at the Friedman School of Nutrition Science and Policy at Tufts University and lead study author, in a phone interview.

Chipotle & fast casual growth trends
Chipotle & fast casual growth trends   

Many of the items, especially when combined as a meal, contained a significant portion of an individual's calorie and sodium intake.

Although fast-food chains are often maligned for super sizing portions, Lichtenstein said the findings didn't support that sizable increases had occurred.

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"They've been accused of continually increasing portion size, and I think that's not the case," she added.

Differences varied widely between the chains, which were selected because they sold similar items, had a national presence and were in the top 10 for total US sales revenue.

These differences highlight why just urging someone to get a smaller size fry isn't really precise enough advice, Lichtenstein said, adding that digging deeper into companies' nutritional data is what people should be doing instead.