USDA publishes an interesting report on food weight and price using a consumer purchase survey factored across values for a recommended diet (in the United States).
I would suspect that Fitbit customers would find the data useful as a value of ballpark reference (how much should I spend on food weekly and what is a recommended portion size by age and gender). Whats more is that Fitbit seems to use or collect an actual or more specific caloric intake whereas USDA is using some static reference population do define age and gender.
May be a long shot to get integration but an interesting take on Food Intake is reference value by weight. In collaboration with data stream improvements, Fitbit could market a food-grade scale to improve portioning at meals (multi-variate analysis nerds rejoice).
https://www.cnpp.usda.gov/USDAFoodPlansCostofFood
https://www.cnpp.usda.gov/sites/default/files/usda_food_plans_cost_of_food/FoodPlans2007AdminReport....
