I like the idea of integrating it into online streaming Alper Yaglioglu suggested! Also, a few years ago I visited the Smart House at the Museum of Science and Industry at Chicago and it had a bike powered tv in the kid's room. Maybe another function would be to target a part of the component specifically at parents who want to see their kids go outside more. And I think kids would gladly embrace it as an extra challenge in the game, and try to outdo their friends with the "rare" or "cool" merchandise they can get with the extra points.
I like the 50/50 idea that Burt A suggested. Personally I was thinking that I would get this app in order to veganize some, but not all of my meals. Some of my favorite Colombian traditional dishes just would not taste the same without the meat, but I have veganized or vegetarianized others in the past for some of my friends. I think a simple but useful add-on to this app would be able to track how many meals you veganized, perhaps in a calendar of some sort. This would not really be for people who are fully vegan, but rather for those who are transitioning or just trying to have a little bit of extra healthiness in their lives.
I love this idea! And I feel that the presentation method allows you to explain the logic and reasoning behind each facet of your final proposal. I agree with the previous comments, and I like seeing the progress with the development and prototyping. Although this is similar to what you mentioned in your prototyping goals, may I also suggest using QR codes? You could set up food around a room with the different calculated values inputed into QR codes, when people scan them, a simple app can add up the values, and then this would be what would be shown at "checkout", with all the nutritional information as well as price.