Hi Rich. In a nutshell, Nutrisystem is a way to count calories without having to count calories. The meals come in set calorie amounts. Flex meals are one step closer to counting calories on your own, because they include a protein source and a healthy-carb source within a set calorie range (about 100 calories each). Weight loss just requires that you eat less calories than your body needs to get through the day. You can use a TDEE calculator to get a rough idea of how many calories your body uses to just ‘exist’ each day, and then you want to eat about 500 calories less than that amount per day, (or about -3500 per week) in order to lose about 1 pound per week which is the most common goal for weight loss as it’s viewed as a very healthy amount to lose per week. You could technically lose weight by just eating flex meals because they are calorie-based, but they just focus on protein and carbs and you should be eating veggies and so on as well. So I personally wouldn’t recommend it – but it als just seems to me that if you have the self-control to count calories and pay attention to your protein, fiber, carb, etc intake that you could just count calories using a program like myfitnesspal and that would be more straightforward.