The definition of fast food in published studies

There are an increasing number of studies being published attempting to delineate a relationship between “fast food” and health. A key factor in assessing the validity of such study results is a common definition of what constitutes “fast food”. To determine how fast food is being defined, 55 epidemiologic studies were reviewed that presented findings for primary or secondary data analyses using “fast food” as an analytical variable. Of these, 10 defined fast food as the specific restaurant or food item used in their study, 8 defined it as the type of service provided (such as no wait staff and take away food), 6 defined it as restaurant food or food obtained outside the home, and 31 did not provide any specific criteria beyond “fast food” or “fast food establishment”. The term “fast food” is inconsistently classified across research studies and is not based on differences in food types, nutritional content or other health/nutrition related variable. The criteria for defining fast food are often arbitrarily ascribed to the study participants’ subjective perceptions of fast food, and not based on scientific or nutritionally meaningful characteristics of the food consumed. The lack of a consistent definition of what constitutes “fast food” is a serious methodological flaw which calls into question relationships inferred by the results. Funded by the McDonald’s Corporation.