Researchers at Milliman, Inc. and Brigham Young University wanted to determine if model size affects purchase intention and overall brand belief about specific diet and non-diet food product types.
Participants in the study were shown ads for 30 seconds, as they would appear in a magazine, then they were asked to complete a questionnaire. Advertisements “featured either a thinner or heavier size model selling either a diet or non-diet product.”
Overall, the thinner model appeared to boost purchase intent and brand belief of diet products while the heavier model had a negative effect on brand belief and purchase intent for diet products. Finally, the study did not show any evidence that the model size would affect purchase intent and brand belief for non-diet products.
To read the full text of the study: Westover, M. L., & Randle, Q. (2009). Endorser weight and perceptions of brand attitude and intent to purchase. Journal of Promotion Management, 15(1-2), 57-73.