Dr. Sherry Pagoto is totally right about the limitations of mobile apps for weight loss. The whole piece is worth a read, but this point is key:
The vast majority of apps are tools for weight, diet, and activity tracking. Apps do a great job here, but these strategies represent a very small segment of a much larger body of effective behavioral strategies that are used to help people lose weight. The situation is tantamount to asking someone to build a house but giving them only a hammer.
As I’ve mentioned, app form is critical but function is what gets the job done.