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Meal Size, Not Body Size, Explains Errors in Estimating the Calorie Content of Meals

Brian Wansink, PhD; and Pierre Chandon, PhD
[+] Article, Author, and Disclosure Information

From Cornell University, Ithaca, New York, and INSEAD, Fontainebleau, France.

Acknowledgments: The authors thank James E. Painter, Jill North, and Jennifer Wansink for their help with data collection in the pilot study.

Grant Support: None.

Potential Financial Conflicts of Interest: None disclosed.

Requests for Single Reprints: Brian Wansink, PhD, 110 Warren Hall, Cornell University, Ithaca, NY 14853-7801.

Current Author Addresses: Dr. Wansink: 110 Warren Hall, Cornell University, Ithaca, NY 14853-7801.

Dr. Chandon: INSEAD, Boulevard de Constance, 77300 Fontainebleau, France.

Author Contributions: Conception and design: B. Wansink, P. Chandon.

Analysis and interpretation of the data: B. Wansink, P. Chandon.

Drafting of the article: B. Wansink, P. Chandon.

Critical revision of the article for important intellectual content: B. Wansink, P. Chandon.

Final approval of the article: B. Wansink, P. Chandon.

Provision of study materials or patients: B. Wansink, P. Chandon.

Statistical expertise: B. Wansink, P. Chandon.

Administrative, technical, or logistic support: B. Wansink, P. Chandon.

Ann Intern Med. 2006;145(5):326-332. doi:10.7326/0003-4819-145-5-200609050-00005
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In study 1, trained interviewers asked overweight and normal-weight persons who had finished eating at fast-food restaurants to estimate the number of calories in their meals and to provide their heights and weights. At the same time, the interviewers unobtrusively recorded the type and size of the food eaten. Although externally valid, study 1 cannot rule out the possibility of self-selection biases (because some people declined to participate in the study) and motivational biases (because some people may have been more motivated by fear of embarrassment than by a desire for accuracy). Another limitation is that the meals varied in both size and type of foods.


calories ; overweight

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Grahic Jump Location
Figure 1.
Actual and estimated calories of self-selected (top) and experimenter-selected (bottom) fast-food meals by normal-weight and overweight participants.

Circles are individual estimates. Squares are geometric means for small, medium, and large meals, determined by a 3-way split of the meals estimated by overweight or normal-weight participants in each study. The model prediction for the actual (A) and estimated (E) calories was E = 12.4 × A0.56 for self-selected meals and E = 10.8 × A0.63 for experimenter-selected meals.

Grahic Jump Location
Grahic Jump Location
Figure 2.
Distribution of actual and estimated calories of self-selected (top) and experimenter-selected (bottom) fast-food meals by normal-weight and overweight participants.
Grahic Jump Location




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Summary for Patients

Meal Size Explains Errors in Estimating How Many Calories Are in a Meal

The summary below is from the full report titled “Meal Size, Not Body Size, Explains Errors in Estimating the Calorie Content of Meals.” It is in the 5 September 2006 issue of Annals of Internal Medicine (volume 145, pages 326-332). The authors are B. Wansink and P. Chandon.


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