Mistaken perception of lipid intake and its effects: a randomized trial

BACKGROUND: Although the Transtheoretical Model (TTM) is promising for behavioral interventions, it may be limited by an inability to understand perceptions of food consumption. The following questions and gaps presented by the scientific community prompted this study: What is the concordance between perceived and actual food consumption? What proportions of individuals are in the pseudo-maintenance (PM) stage (overly optimistic perception of fat consumption)? What is the proportion of individuals in the non-reflective action stages (adequate fat intake but do not recognize it)? Is it necessary to develop specific strategies for individuals in these stages? Therefore, the present study aimed to identify the proportion of “pseudo-respondents,” or those in the PM and non-reflective action stages, and to explore subgroup effects by PM classification. METHODS: In a previously conducted randomized controlled trial, participants in the usual care group (UCG) and the TTM-intervention group (TM-IG) were post-hoc classified as “true respondents” or “pseudo-respondents”; the latter included those in the PM (mistakenly perceived their lipid intake as adequate) or non-reflective action (did not recognize the adequacy of their lipid intake) stage. The 6-month TTM-based intervention for fat consumption was performed with a sample of Public Health Service users. RESULTS: Seventy-one women completed all of the phases. About half of the participants were in the PM stage (UCG: 14 of 31; TM-IG: 19 of 40), and only two were in the non-reflective action stage. Post-intervention, PM individuals in the TM-IG evolved differently, with greater progression to later stages of change and reduced calorie intake, weight, and body mass index (p < 0.05). CONCLUSIONS: Owing to the high proportion of participants in the PM stage and the differing performance, this stage is important. The intervention had a previously unreported differential effect on the progression of the stage of change and nutritional status by PM classification. TRIAL REGISTRATION: RBR-5TDHZY (retrospectively registered in August 2017 in Brazilian Registry of Clinical Trials). ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s40795-017-0193-8) contains supplementary material, which is available to authorized users.