Introduction:

Health programs that compared a tailored- intervention group to a control one for adolescents obtained satisfactory post-intervention results. However, not all studies that compared a tailored intervention group to a non-tailored intervention group achieved the expected results, and most of these programs did not deliver similar contents for all groups, making it difficult to compare the results.

Objective:

The study aimed at comparing the effects of a stage-tailored nutritional intervention to a non-tailored one for adolescents.

Methods:

Eight schools were randomly selected, and a total of 347 students participated in the study. A WhatsApp-based intervention was implemented in three groups: stage-tailored nutritional educational group, a non-tailored nutritional educational one, and a control group. Daily messages were sent to all students for 42 days, one per day. The content of the messages was similar on both nutritional intervention groups, but for the tailored one it was considered the stages of change and processes of change for personalization. Control group received messages on another health theme. Food consumption, stage of change, nutritional knowledge, and self-efficacy for adopting healthy eating behaviors were measured. Wilcoxon test, Kruskal-Wallis rank test and the pair-wise comparison method, and Pearson’s chi-square test were performed.

Results:

Intra-group analyzes revealed that the tailored group showed a significant increase in the scores of knowledges and self-efficacy and a decrease in the score of unhealthy eating. Comparing the groups, the tailored intervention showed a significant increase on items of the self-efficacy’ scale.

Conclusions:

The tailored group showed to be the most suitable format for nutritional interventions via WhatsApp for adolescents.