A Focused Review of Smartphone Diet-Tracking Apps: Usability, Functionality, Coherence With Behavior Change Theory, and Comparative Validity of Nutrient Intake and Energy Estimates

Giannina Ferrara   ^{1 *} , BA ;   Jenna Kim   ^{2 *} ;   Shuhao Lin   ^{3 *} , BS ;   Jenna Hua   ⁴ , BSc (hons), RD, MPH, PhD ;   Edmund Seto   ⁵ , AB, MS, PhD

¹ Global Burden of Disease, Institute for Health Metrics and Evaluation, University of Washington, Seattle, WA, United States

² Paul G. Allen School of Computer Science & Engineering, University of Washington, Seattle, WA, United States

³ Department of Kinesiology and Nutrition, University of Illinois, Chicago, Chicago, IL, United States

⁴ Stanford Prevention Research Center, Department of Medicine, Stanford University, Stanford, CA, United States

⁵ Department of Environmental & Occupational Health Sciences, University of Washington, Seattle, WA, United States

*these authors contributed equally