Simple Diet Diary is an Android application designed to help users lose or gain weight by tracking their diet. The app allows you to quickly log the food you consume and track as many or as few nutrients as you like, including the ability to invent your own. You can easily look up nutrient values in the offline database or enter them manually. The app also lets you select previously entered foods, view graphs of nutrient history, and display each day's total or remaining nutrient allowance.

Additionally, you can share your data as HTML, CSV, or SQLite database, and there are home-screen widgets for quick viewing of your totals. The premium version of the app unlocks features such as customizing the widget appearance, sharing daily totals and item data, altering the date range when sharing data, selecting the dark theme, dynamically adjusting targets, and choosing actions for double-tap and long-press on the totals bar.

The app requires permission to access your photos, media, and files for reading and writing backup files on the SD card. The in-app purchase permission is required for a single purchase to unlock the premium features. Simple Diet Diary is a useful tool for those looking to track their diet and achieve their weight goals.