When it comes to food choices, what counts is quality.
Credit: Illustration: Shaw Nielsen

Calories are one of the first items listed on the Nutrition Facts label of packaged foods, and many of us approach them like a dietary bogeyman, fearing too many will make us fat. "Americans have such a negative connotation about the word 'calories,' " says Carolyn Williams, PhD, RD, contributing nutrition editor for Cooking Light. "But calories are just a measure of energy in food."

Here's a surprise: Many nutrition experts aren't fans of counting calories. "A lot of our patients try really hard to count and restrict calories, and it doesn't work," says Barbara Gower, PhD, a professor of nutrition science at the Nutrition Obesity Research Center at the University of Alabama at Birmingham. "I tell patients, 'The reason you can't lose weight isn't because you can't do math.' It just isn't that simple."

So what do you need to know about calories? Start by letting go of the myths outlined in below.

It seems counterintuitive, but eating too little actually makes it harder to lose weight. "If you restrict too much, your body goes into starvation mode," says Traci Mann, PhD, a professor of food psychology at the University of Minnesota Twin Cities and author of Secrets from the Eating Lab. As you eat less, your metabolism adjusts to run on fewer calories.

Then there's the stress that comes with dieting: Mann's research has found restricting and counting calories boosts levels of cortisol, a stress hormone linked to–you guessed it–weight gain.

Try this: If you must count calories, limit it to just a week. This will reveal plenty about the quality and quantity of your diet.

"The whole calories-in-calories-out argument is so simple and appealing. That's the beauty of it," says Gower. "The downside is, that's just one piece of the story." That's because the way our bodies use calories is complex.

"The idea that humans are just buckets that you pour calories into the top and calories come out the bottom isn't supported by the evidence," says Dariush Mozaffarian, MD, DrPH, dean of the Friedman School of Nutrition Science and Policy at Tufts University. "And the evidence is strong that total calories isn't the right thing to focus on in most cases."

He calls calorie-counting "a distraction" that often leads to poor nutritional choices. "There's an endless list of personal, food industry, and government decisions that are at best useless and at worst harmful because of the focus on total calories," says Mozaffarian. Examples range from school nutrition programs that favor sugar-laden chocolate skim milk over plain whole milk to food manufacturers who cut out healthful fats to trim calories.

Try this: Make smarter choices. A 100-calorie snack pack of cookies offers little in the way of nutrition compared to 100 calories' worth of nuts, which contain protein, minerals, and vitamins in addition to calories.

How your body uses calories depends on the quality of the food around the calorie. "What you eat is way more important than how much you eat for your overall health," says Mozaffarian. "The foods we eat have very different effects on brain reward and cravings; on liver function; on production of fat; on our glucose, insulin, and other hormonal responses; on our gut microbiome; and on our fat-cell responses."

"Calories are like gas in a car," says Williams. "The quality of gas you put in affects how your body runs. It really does matter what those calories are, especially for satiety and energy–250 calories of fruit and nuts are different from a 250-calorie honey bun." Fruit and nuts are full of satisfying fiber, protein, and fat, while the honey bun is a refined-starch bomb that will have you prowling for a snack an hour later.

Feed it right, and your body does a good job of managing your appetite and regulating calories without your having to count. Gower's research has found that shifting some calories away from carbs and toward healthful fats and (a little) more protein helps people shed belly fat while maintaining more lean muscle mass than they do on a higher-carb diet.

"We just tell our patients, 'Eat fat and protein because you won't overeat. Focus on the quality of what you're eating, and the rest will take care of itself,' " says Gower.

Try this: Calories from fat and protein are more satisfying than carbs because you digest them more slowly, which signals your brain to stop eating.

Bonus Tip: Writing down what you eat—vs. counting calories—is a saner way to keep your diet in check. Read more in A Saner Way to Track Calories.