Thinking about health: How many calories are in that Big Mac?

When you next eat at McDonald’s, here’s an exercise in consumer choice: Would you choose a Bacon Club House burger with 750 calories, a Big Mac with 550 calories, or the premium McWrap with bacon and grilled chicken giving you 460?

You might think twice if you knew that one option gave you 300 calories more than another and, all by itself, proved you with over one third of the calories you need for the day (based on a 2,000 calorie diet).

Beginning in the summer 2015, you’ll be able to figure it out. That’s when a provision in the Affordable Care Act that requires chain restaurants with 20 or...