Personalized Dietary Feedback Mediates the Association of Dietary Self-Monitoring Adherence and Weight Loss: A Post Hoc Analysis of the Personal Diet Study.

BACKGROUND

Dietary self-monitoring is central to effective personalized nutrition, providing critical data to inform tailored feedback and support behavior change.

OBJECTIVES

To examine the impact of dietary self-monitoring adherence and the indirect effect of personalized scores to predict postprandial glycemic response (PPGR) on weight loss.

METHODS

Post hoc analysis of the Personal Diet Study that investigated the impact of a machine algorithm-based diet that integrates clinical and microbiome features (Personalized) compared with a standard, low-fat diet (Standardized) on weight loss. All participants received behavioral counseling and were encouraged to self-monitor dietary intake via a smartphone application. Personalized received algorithm-based scores (1-5) on predicted PPGR to foods logged (PPGR score; 1-2 indicating optimal; 3-5 suboptimal). Dietary self-monitoring adherence was the percentage of days logging ≥50% of target calories, classified as high or low. PPGR score quality was calculated by the proportion of optimal predicted PPGR scores per day; defined as "high-PPGR quality" days when this exceeded the group average. Mediation analysis assessed whether PPGR quality mediated the relationship between dietary self-monitoring adherence and weight loss.

RESULTS

Participants with high self-monitoring adherence lost an average of 4.2% of their baseline weight, compared with 1.9% among those with low adherence (P = 0.016). High self-monitoring adherence was associated with a greater likelihood of achieving ≥5% weight loss (adjusted odds ratio: 3.67; 95% confidence interval: 1.63, 8.50). Within Personalized, high-PPGR quality mediated 53.4% of the total effect of self-monitoring adherence on weight loss (P < 0.001).

CONCLUSION

Consistent self-monitoring coupled with personalized feedback may significantly enhance weight loss in a precision nutrition approach. This trial was registered at https://clinicaltrials.gov/ as NCT03336411.