Background: Dietary interventions are effective prevention and treatment strategies for chronic diseases; however, they require extensive commitment, time, and resources. Dietary mobile applications (apps) have gained popularity and are thus being incorporated into dietary management.

Objective: The aim of this review is to assess the effects of the use of dietary mobile apps on nutritional outcomes in adults with chronic diseases.

Methods: A systematic review was conducted following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines using MEDLINE, PubMed, Embase, and CINAHL databases. The protocol was registered on PROSPERO. Intervention studies evaluating the nutritional outcomes of dietary apps, published in English between January 1, 2007 and November 15, 2017 were included. The methodological quality of included articles was assessed via the Academy of Nutrition and Dietetics' Quality Criteria Checklist: Primary Research. Heterogeneity was confirmed using the I² index and a random-effects meta-analysis was performed for randomized controlled trials. Estimates of the pooled mean difference were calculated for app usage compared to no app usage.

Main outcomes measure: Nutritional outcomes, categorized as food-/nutrition-related, anthropometric measurements, pertinent clinical/biochemical data, and nutrition-focused physical findings, were extracted from the included intervention studies.

Results: Upon completion of the searches, 18,649 articles were identified, and data were extracted from 22 articles. Pooled estimates showed a significantly greater decrease in weight (-2.45 kg, 95% CI -3.33 to -1.58 kg; P<0.001; I²=96.2%, 95% CI 95% to 97%), waist circumference (-2.54 cm, 95% CI -3.34 to -1.73 cm; P<0.001; I²=88.3%, 95% CI 67% to 96%), and energy intake (-149.52 kcal, 95% CI -215.78 to -83.27 kcal; P<0.001; I²=0% CI 0% to 90%) when an app was used compared to control.

Conclusions: The findings of this systematic review and meta-analysis indicate that dietary mobile apps are effective self-monitoring tools, and that their use results in positive effects on measured nutritional outcomes in chronic diseases, especially weight loss.