I think they suggest MFP to make sure the macros match up, and if your subbing foods? I used it when meal prepping all my meals for this week (not every day cause all my meals are the same) but just the day I made the food so I know what I’m making matches the total macros. For example, I made the M4O1 for this week, but subbed bok choy instead of cauliflower. I scanned and entered all the foods, but I somehow ended up with 75g C. All meals should be 35g C, so I lowered the number of grams of quinoa to make the total carbs for the meal 35g, so all my macros for the day match up. Maybe I was using different brands than Nicole did while calculating the macros of the meals.