You can just weigh yourself periodically, weigh what you consume, and then compute how much mass has left your body. As a diet, you could plan out what you wan

You can just weigh yourself periodically, weigh what you consume, and then compute how much mass has left your body. As a diet, you could plan out what you want to weigh over time, and then before each meal calculate how far below that goal you are and limit your consumption to the difference.