I was late for my plane over the holidays but that didn't keep me from taking a few extra minutes to place my order. I was standing at the Dunkin' Donuts counter in JFK, weighing two numbers: 2.16 and 510. Which one do you think was the number of calories in the muffin?

The first was the price of a muffin in dollars. The second, the cost of the muffin in calories. Could just seeing those two numbers propel me to count my calories in the same way I might count my pennies? (Find our top 5 picks for healthy foods at the airport.)According to the authors of the Health Care Reform Bill, the answer is yes - so much so that more than 200,000 fast food outlets (as well as vending machines) will be required to post calorie counts on the foods they sell.

But will it work? According to a study released in January 2010, the answer is "yes" again. Researchers at Stanford Graduate School of Business (yes, a graduate school of business, not of health) looked at how posting calorie counts in Starbucks locations in New York, Boston and Philadelphia affected consumer behavior and buying patterns. Their conclusion: posting calorie counts caused people to consume anywhere from 6% to 26% fewer calories, for those whose average purchase was more than 250 calories. (You'll save money and calories when you make one of these 10 delicious breakfasts to help you lose weight.)

"Listing calorie counts eliminates guesswork," says Nicci Micco, EatingWell's deputy editor of nutrition and co-author of the new book EatingWell 500 Calorie Dinners. "Research shows that consumers underestimate the calories in restaurant foods by up to 956 calories. So even if you do go for a burger, fries and shake, knowing how many calories you just ate may encourage you to eat lighter at your next meal."

The second part of their finding: calorie posting-which became mandatory for all New York restaurants with 15 or more outlets in 2008-did not hurt Starbuck's bottom line. In fact, at some outlets it increased revenues, contrary to the fears many chain restaurants expressed when the law went into effect.

Certainly this is good news for restaurants that are posting calorie counts, like Applebee's, which this month announced its "Unbelievably Great Tasting & Under 550 Calories" menu. It may be even better news for us as consumers. Armed with precise calorie counts, we are now better equipped to manage our diets in the same way we balance our checkbooks. (Get a 28-day meal plan of delicious recipes for breakfast lunch and dinner to help you lose weight.)

If I had only 15 dollars to spend on food for the day, would I spend $2.16 of that on a muffin? Likewise, if I am to keep to a diet of 1500 calories a day-a count I'm using to get down to my healthy weight goal-should I be allocating more than a third of my calories to a sugary breakfast or saving them for a delicious meal of sautéed chicken cutlet, asparagus and mashed potatoes (also 500 calories)? (Click here to find fresh ideas for diet-friendly breakfasts for 350 calories or less, 400-calorie lunches and 500-calorie dinners.)

Of course, as with financial planning, calorie planning should include some splurges. A small 100-calorie chocolate snack can satisfy a sweets craving, keeping you from splurging on a 400-calorie cupcake, in the same way that buying a new $30 scarf may curb your impulse to buy $200 shoes. (Find 10 days of easy 100-calorie snack ideas here.)

The current financial recession may be what finally spurs our generation to save for the things we need, like college educations and down payments on homes.

How long before the current obesity epidemic teaches us to budget our calories for the foods we need (such as filling whole grains and nutrient-rich vegetables and fruits) instead of splurging on the foods we crave? Could you live without fast food?

One in four Americans is now obese, making us the fattest nation in the world and resulting in a spate of diet-related deaths from diabetes, stroke and heart disease.

Though critics have pointed out that caloric information is readily available, New York City took a bold step in 2008 when it became the first city to require calorie labeling at point of purchase-giving calorie counts equal status to pricing-at chain restaurants. Others are now following suit.

By January 2011, California will require all restaurants with 20 or more outlets to post calories on menus. How long before we'll adopt this at a national level, weighing the costs (obesity-related health care alone costs the US $147 billion a year) and benefits of such information?

How long before we'll all be thinking about balancing our calorie intake the same way we balance our checkbooks? The benefits are two-fold: not just a richer life, but a longer and healthier one.

After looking longingly at that Dunkin' Donuts muffin for a long time, I heard the final boarding call for my flight. I bought an apple: $1.30, 95 calories. (Make every penny count with these 6 superfoods for $1 or less.)

(updated 3/31/10)