The mantra is the same everywhere you turn… weight loss is a matter of ‘calories in’ and ‘calories out’ and in order to know what we are consuming and expending, we are generally asked to self-monitor the amount of food we eat and exercise we do.  There are a lot of good tools (e.g. food diaries, etc) for helping us monitor ourselves.  However, a new study published in the January 2010 issue of the Journal of the American Dietetic Association reports that keeping track of the calories we consume is even more difficult that most of us imagined.  

Since most of us today find ourselves eating at restaurants or purchasing frozen convenience meals, researchers from Tufts University decided to measure the calorie content of several restaurant foods and supermarket convenience meals and compare them with the values stated by the makers of the foods.  For the frozen foods, the meals were tested as provided right out of the package.  For restaurant foods, calorie content was analyzed based on the serving provide by the restaurant and based on the portion size listed in the restaurant nutrition literature when possible.  The results of this analysis showed that on average, restaurant foods contained 18% more calories than stated (ranged from 37% fewer calories to 200% more calories than stated).  The results from the analysis of the frozen convenience meals were more accurate with these meals containing only 8% more calories than stated on average (ranged from 10% fewer to 31% more than stated).  Some examples are shown below:

•  Brown rice pilaf = 240 stated calories; 322 measured calories
•  Chicken taco salad = 326 stated calories; 607 measured calories
•  Shrimp primavera = 548 stated calories; 624 measured calories
•  Grilled chicken wrap = 295 stated calories; 344 measured calories
•  Frozen shrimp & angel hair pasta = 250 stated calories; 319 measured calories
•  Frozen lemon herb chicken piccata = 252 stated calories; 306 measured calories

The study researchers believe that the frozen convenience stores were more accurate possibly because of U.S. FDA regulations regarding Nutrition Facts panels on packaged foods.  Additionally, restaurant foods were typically provided in serving sizes that were greater than portion sizes stated in the restaurant nutrition literature, thus contributing to the excess calories.

The inaccuracies in reported calorie content of restaurant and frozen convenience meals make our job of self-monitoring our calorie intake that much more difficult.  While the average values of 8% and 18% do not seem like a lot, over time these extra calories might result in substantial, unexpected weight gain.  So remember to keep portion sizes in mind whether you are preparing food at home or dining out and remember our tips for eating healthy while eating out (Part 1 and Part 2).

Reference

Urban LE, Dallal GE, Robinson LM, Ausman LM, Saltzman E, Roberts SB.  The accuracy of stated energy contents of reduced-energy, commercially prepared foods.  Joournal of the American Dietetic Association 2010; 110:116-123.