I used an app with a barcode scanner and a huge library of products. It not only tracked calories but gave a nice daily count on fat, protein, carbs and sugar.

I used an app with a barcode scanner and a huge library of products. It not only tracked calories but gave a nice daily count on fat, protein, carbs and sugar. Simply staying under 2100 calories will drop your weight. No doubt! However, if you want to be able to maintain that long-term, you need to figure out what to eat so that you get the right balance of carbs, sugars, fats and protein. If you don't then you're either gonna be continually hungry or malnourished (or probably both). By using the app long-term I developed a set of recipes (that can be modified so I don't get bored) which make up my foundational diet. This is now sustainable without the app, and without cognitive load or will power.