If you're like most people, you already know fast food is bad for you, and are very "generous" when estimating how frequently you eat it.
While it is possible you're improving your frequency, our minds can't be trusted to accurately remember information like that, especially if we know we shouldn't be eating it as frequently.
There are many apps that help you track and improve on such habits, but those apps also record all that data and use it to sell you more stuff, or simply sell it to other companies, so those can sell you more stuff.
Loggit isn't like that. You own your data and only you have access to it. It's only on your device, and if you want to synchronize it across devices, you can set up your own server for it. The database synchronization engine is open source (CouchDB/PouchDB) .
It's also much simpler, and that puts you in control of what you should do with your data.