  Obesity is known to lower the quality of life substantially. It is often
associated with increased chances of non-communicable diseases such as
diabetes, cardiovascular problems, various cancers, etc. Evidence suggests that
diet-related mobile applications play a vital role in assisting individuals in
making healthier choices and keeping track of food intake. However, due to an
abundance of similar applications, it becomes pertinent to evaluate each of
them in terms of functionality, usability, and possible design issues to truly
determine state-of-the-art solutions for the future. Since these applications
involve implementing multiple user requirements and recommendations from
different dietitians, the evaluation becomes quite complex. Therefore, this
study aims to review existing dietary applications at length to highlight key
features and problems that enhance or undermine an application's usability. For
this purpose, we have examined the published literature from various scientific
databases of the PUBMED, CINAHL (January 2010-December 2019) and Science Direct
(2010-2019). We followed PRISMA guidelines, and out of our findings, fifty-six
primary studies met our inclusion criteria after identification, screening,
eligibility and full-text evaluation. We analyzed 35 apps from the selected
studies and extracted the data of each of the identified apps.Following our
detailed analysis on the comprehensiveness of freely available mHealth
applications, we specified potential future research challenges and stated
recommendations to help grow clinically accurate diet-related applications.
