Starting your meal with something healthy like a salad could cut the number of calories you eat – and not just because you’re filling up on fiber.

Our ability to estimate calories is influenced by the order in which we eat, according to a study in the April 2011 Journal of Consumer Psychology. When we start with something we perceive as healthful, such as a salad, we tend to overestimate the calories in less healthful food that follows, such as a cheeseburger and fries. And that can help us eat less of the fattening stuff.

"We stereotype food into vices and virtues," says Alexander Chernev, PhD, a behavioral scientist at Northwestern University's Kellogg School of Management in Evanston, Ill.

When a broccoli salad, a “virtue,” is followed by a slice of chocolate cake, a “vice,” consumers overestimate the number of calories in the chocolate cake.

"The vice seems even vicier," Chernev says.

Is Overcounting Calories Better for You?

Previous studies have shown that people are generally bad at calculating calories; consumers underestimate the caloric total of large meals and how many calories they eat over the course of a day. Another study led by Chernev showed that dieters tend to believe that adding a healthy option like a small salad to an otherwise indulgent meal will lower the total calorie count of the meal.

But in his new study, Chernev says consumers might be able to take advantage of their inaccurate guesses. If underestimating calories causes them to consume too much food, overestimating may help them eat less.

Just make sure you estimate the calories in that salad before you look at the cheeseburger.

Eating Out Made Easier

Counting calories when eating out became a little easier with the 2010 Patient Protection and Affordable Care Act, which requires restaurants with 20 or more locations to post calorie counts on their menus.

The idea is to help consumers make healthier choices about the food they order. But will knowing that a cinnamon crunch bagel from Panera bread has 430 calories or that Chili’s avocado burger on wheat has 1,520 calories influence how people order?

So far, research in cities that already require restaurants to post calorie data isn’t promising. In New York City, two studies have found that adults and children see the new counts, but aren’t changing their ordering behavior.