What if grocery receipts included calorie counts?

My most recent grocery bill was $195, but how many calories did I bring home? If exactly everything was consumed by 4 people in equal portions over the next week (7 days), then how many calories will I have consumed? Websites with nutrition information are legion on the internet (with 88 million results for “nutrition” on Google, 2010-10-20), but finding the time to apply it all is difficult [even under the amazingly optimistic assumption that you can sort out what is correct and what is not]. It may be a heuristic, but you more or less eat all the calories that you purchase and bring home from the grocery store (unless you are throwing out a lot of uneaten food or throwing parties where you provide food to the guests). America already has a law that mandates calorie counts for restaurants [2][3][4], barcodes already link to price data, and all the packaged food sold in the store has nutrition labels. What would the public effect be of printing a total calorie count at the end of grocery store receipts?

[1] : “SELF Nutrition Data” by NutritionData.com © 2009 Condé Nast Digital, 2010/10/20

[2] : “Fast Food Calories News Reveals Health Care Restaurant Law” by Andy Hodges, 2010/03/25

[3] : “FDA releases guidance on federal menu labeling requirements” by U.S. Food and Drug Administration, 2010/08/24

[4] : “The Patient Protection and Affordable Care Act” see section “4205” by One Hundred Eleventh Congress of the United States of America, 2010/01/05