Wednesday, December 10, 2008

Flawed Study on Effects of Calorie Labeling On Fast Food Meal Choices

Effects of calorie labeling and value size pricing on fast food meal choices: Results from an experimental trial.

A recent study published in the International Journal of Behavioral, Nutrition and Physical Activity concludes that additional research is needed to better evaluate the effects of calorie labeling and value size pricing on fast food meal choices.

It reaches this conclusion based on its published results which finds no significant differences between the average energy content (calories) of meals ordered from a menu that included calorie information (without value-size pricing) as compared to those meals ordered from a menu that did not include calorie information (but had value-size pricing). In other words, it found no meaningful difference in food choices when calories were posted on the menu. The study reports similar results across age, race and education levels.

This is a deeply flawed study.

The study should not have tried to tackle both calorie information and value-size pricing, particularly where it acknowledges that most participants did not understand the value-size pricing component. It only served to confuse the results.

There was no context given to participants regarding the calorie information. The study says, “[T]o put the calorie information in context the average daily calorie needs of adult men and women were provided in a ‘Calories Count’ information box in the right hand bottom corner of the menu.” Women were told that “most need less than 2000 calories in a day.” Men were told that “most need less than 2400 calories in a day.” The web site posts those calorie amounts for males and females between 19 and 30. But, for women and men between 31 and 50, calories would be 1800 and 2200, respectively, and for 51-plus, 1600 and 2000 calories, respectively. Age participants in the study ranged from 16 through 61+, and many were given incorrect information about their calorie needs.

There was also no information given as to what intake of calories beyond 2000 and 2400 would mean to participants. There was no mention of weight gain, high blood pressure, obesity, coronary heart disease, diabetes, increases likelihood of stroke, or any of the other effects of over intake of calories. No health organization or municipality trying to affect change by posting calories is doing so in a vacuum. Public education campaigns accompany calorie posting laws in every jurisdiction that has enacted menu board laws.

Also, although the study was just published, the data collected was from October 2005 and April of 2006, a time before a single jurisdiction in the country passed a calorie posting law.

The study should have considered the methodologies used by Mary Bassett, MD, MPH and others, and collected its data from actual register receipts from purchasers at fast food restaurants, as reported in the peer reviewed American Journal Of Public Health, August 2008. Having participants order fast food from conference rooms in suburban hotels or church basements does not reveal real-time live food choices.

The study should have chosen participants from a jurisdiction that has already passed a calorie posting law, so there would at least be some likelihood that participants received some education as to the dangers of excessive calorie intake.

The study included the results as between males and females; between those that reported the importance of nutrition in fast food purchases; and, between those that reported the importance of price in fast food purchases -- three distinct groups. The authors gathered demographic information on body mass index (BMI), but did not report differences in behavior among those with normal BMIs, those considered overweight, and those considered obese.

The data does shows that significantly lower calorie intake among those reporting that nutrition was important when buying fast food. This would indicate that those persons educated as to the effects of nutrition availed themselves of the calorie information to make meaningful choices.

Also, the study has a methodological weakness. Participants were exposed to the calorie information on only one occasion, a critical shortcoming especially if repeated exposure to calorie information is required before awareness or behavior change can be expected.

Lack of context of the calorie information was perhaps its greatest fault. Participants were only told that they need less than a certain number of calories per day, but were not told what they need them for. Also the wording of the calorie information was awkward. A second group of participants should have been told that eating more than a specified number of calories could have a detrimental health affect.

The research was supported by a grant from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). The study abstract can be found here, and a PDF file of the actual study can be found here. This flawed study will likely become a darling of the restaurant industry.