A Mixed-Methods Evaluation of the Choose Less, Weigh Less Portion Size Health Marketing Campaign in Los Angeles County.

Purpose
To assess the impact of the Choose Less, Weigh Less portion size health marketing campaign. Design . A mixed-methods, cross-sectional evaluation.

Setting
A quantitative Internet panel survey was administered through an online sampling vendor and qualitative interviews were conducted by street intercept.

Subjects
The panel survey included 796 participants, weighted to represent Los Angeles County. Street intercept interviews were conducted with 50 other participants. Intervention . The Choose Less, Weigh Less campaign included print media on transit shelters, bus and rail cars, and billboards; radio and online advertising; and Web site content and social media outreach.

Measures
The panel survey measured self-reported campaign exposure and outcomes, including knowledge of recommended daily calorie limits, attitudes toward portion sizes, and intent to reduce calories and portion size. Intercept interviews assessed campaign appeal, clarity, and utility.

Analysis
Weighted survey data were analyzed using logistic regression to assess the association between campaign exposure and outcomes. Interview data were analyzed for themes.

Results
The campaign reached 19.7% of the Los Angeles County population. Significant differences were seen for 2 of the 10 outcomes assessed. Participants who saw the campaign were more likely than those who did not to report fast-food portion sizes as being too large (adjusted odds ratio [Adj. OR] 1.89; 95% confidence interval [CI] 1.16, 3.07) and intention to choose a smaller portion (Adj. OR 1.99; 95% CI 1.20, 3.31). Qualitative data revealed three themes about appeal, clarity, and utility. Conclusion . Health marketing efforts targeting portion size can have relatively broad reach and limited but positive impacts on consumer attitudes and intent to select smaller portions.