My app lets you scan any barcode for food products and then tells you how many donuts it is. You can also upgrade to change from donut to slice of pizza, snickers bar, m&ms, or other treats.
What do you think of this idea?
In economics, there's a Big Mac Index which lets you measure purchasing power between different countries. A donut is something like 250 calories, but that will vary. I would suggest a donut graphic with 250 in sprinkles to indicate the calories. It would make for a cool app icon, as well!
I don't think using a donut as a measurement makes sense because there isn't a defined single measurement for one.
I've always thought about the 'Mars bar' scale, as this is a defined measurement.