I like the idea and the overall design but on the 'Log' page the top circles are a little confusing. I was trying to tap on them initially and it took me a few minutes to realize that they just showed the status. If they were different then the rest in some way it might make it more obvious.
I would also love Fitbit integration. I know a lot of people who have them (myself included) and because I would still have to use two apps might prevent me from using Nudge long term.
This isn't good advice either though. Many people eat way too many fats and often consume extra protein as well. Carbs should be your main energy source (~65% of your daily calories should come from carbs) with a lot of the rest coming from protein. The solution is to continue to consume large amounts of carbs, but change the source so that the carbs are complex which are generally nutrient rich and provide a great energy source for the body.
I would also love Fitbit integration. I know a lot of people who have them (myself included) and because I would still have to use two apps might prevent me from using Nudge long term.