I had most of my weight loss before discovering this forum and then learning about Fitday. So no, you don't need it. You might also want to carefully read their privacy policy before you create an account and start entering your daily eating habits there.

That said, I recently began using it, and find it a pretty useful tool for catching carbs sneaking into the food supply. It's certainly helping me to keep calories eaten less than calories burned. And yes, it is a time consuming pain in the neck