Seems like a great idea! It's interesting that they focus on low-calorie substitutions instead of healthier substitutions in general. I played with the application, adding a cookie recipe with granulated sugar, whole milk, and butter. It suggested that I use less sugar, butter and low-fat milk but did not suggest using almond milk, coconut sugar or ghee. It would be a great addition to the application if it informed of substitutions, that while might not be less calories, would be better for your health.