Calories are everywhere, peering down from menu boards, getting bigger and bolder on nutrition labels and racking up on FitBits on a nation of nervous wrists.

Last week, federal rules went into effect requiring all chains with 20 or more locations that serve prepared foods to post calories on menus and menu boards, from Chester Chicken at gas stations to popcorn at the movie theater to a glass of wine or beer and a salmon salad at a Whole Foods. Many restaurants, such as Starbucks, Panera and McDonalds have complied with the rule for years, but now all prepared and restaurant foods must be labeled, and a nation already obsessed with calories will get a lot more exposure to them.

Perhaps because of the prevalence of calories, many people overestimate the importance of calories, crunching numbers before they crunch their carrots or cookies.

The intent of the new policy is to allow consumers to make “better” choices, and while it may induce people to choose lower-calorie options, fewer calories does not necessarily guarantee a healthier choice.

What good is calorie counting doing us, anyway? What, in fact, are calories, and why are we so determined to minimize their consumption?

A calorie is a measurement of energy, more specifically, the energy required to heat one gram of water by one degree Celsius. What we refer to as a food calorie, is actually a thousand calories, or the amount of energy required to raise the temperature of a kilogram of water by one degree Celsius.

Kind of boring, right?

Talking about nutrition in terms of calories is like talking about architecture in terms of nails. “Great building, Frank Gehry, but the public wants to know, how many nails are in it?”

Like nails in a building, calories are necessary. Unlike nails in a building, calories are not physical things you can hold in your hand, but a measurement of heat that can be translated to a measurement of energy. In food, that energy is stored in chemical bonds. To qualify as food, our bodies must be able to break the chemical bonds contained therein. Trees, for example, contain billions of calories, but our bodies are unable to access them – we don’t have the enzymes required to digest and use that energy. (In our endless adaptability, however, we access that energy with fire, which can break those bonds, and supply us with warmth – a more direct example of calories as a measurement of heat).

Caloric energy powers millions of reactions in the body every second of the day, allowing us to maintain a temperature of about 98.6 degree F, beat our hearts 60 to 100 times per minute, balance our electrolytes by running millions of teeny-tiny sodium-potassium pumps in each cell, break down and build up tissue constantly, and perform thousands of other reactions.

Because calories are essential to our functioning, our bodies have tightly controlled mechanisms supporting our energy intake and use. Although we do not fully understand all of these mechanisms, they are apparent in our functioning. While each of us consumes nearly a million calories per year, our weight fluctuates very little in that time. When food intake goes down, as in dieting, metabolism slows, reducing the number of calories the body needs and keeping weight more stable. Similarly, when we eat more, metabolism increases, burning more calories. These processes function best when we are able to mindfully listen to our body’s signals of hunger and fullness, and worse when we intentionally ignore those signals. The body knows what it needs, and calorie counting can undermine it by double-guessing it.

Calories aren’t the whole story, either. Our bodies also require vitamins and minerals, cofactors and coenzymes, proteins and fats, adequate hydration and normal temperature. The body is always performing an intricate ballet, for which calories are merely the fuel.

Healthy eating is so much richer and more interesting than counting calories. Food contains calories, yes, but it also has those necessary vitamins and minerals, phytochemicals and antioxidants, carbohydrates, fats and proteins, fiber and fluid, enjoyment and pleasure and the quieting of hunger and headaches.

Also, there are interactions between nutrients within foods that we don’t yet fully understand.

A tomato, for example, contains vitamins A, C and K as well as lycopene, a phytochemical. While all of those nutrients can be taken in pill form, we don’t yet know what we’re missing from the tomato complex itself, or the tomato eaten together with another food. It wasn’t that long ago that we discovered cooked tomatoes allow us to absorb more of that lycopene.

So many traditional foodways include food groupings that maximize the nutrition of each item – rice and beans create a complete protein, salad and dressing allow the body to absorb fat-soluble vitamins and beef and green leafy vegetables eaten together increase the iron available in the greens.

There are likely countless benefits we get from whole foods and pairings and preparations of foods that we don’t know about. Focusing on calorie counting often reduces the types and varieties of food we eat, which may limit our overall health, according to several studies.

Many calorie-counting apps, as well as restaurant menu boards, lead a lot of people to think of calories as a zero-sum game. For example, a lot of calorie apps describe calories in terms of how much exercise would be required to burn off a meal. But your body needs a certain amount of calories for basic function. Your basal metabolic rate, or BMR, is the number of calories you would need if say, you were in a coma with absolutely no movement. This accounts for about 70 percent of your calorie needs and includes your body’s constant tissue breakdown and build-up as well as organ function. The brain uses about 25 percent of that energy alone. Movement accounts for about 20% of calorie use, and digestion takes up 10 percent.

If, therefore, your goal is to burn off all the calories you’ve eaten (calories in, calories out!), you will be at risk of dying.

So, if calories can’t help us maximize our nutrition and wellness, what can?

As a Registered Dietitian working with patients diagnosed with an eating disorder, I go head-to-head with some truly world-class calories counters on a daily basis. They almost always know the calorie counts of food items better than I do.

Through the course of their treatment, however, they learn to focus less on external measures (such as calories) and more on internal signals (such as hunger and fullness). Shifting your focus from calorie counting to your body’s natural ability to regulate intake and output can allow you to truly nourish yourself.

Nutrition advice is, as all nutrition labels will remind you, “based on a 2,000 calorie diet.” This number is meant to be the best advice for 300 million Americans, but cannot take into account the needs of individuals, who each vary day by day. If you’re more active, you need more energy. If you’re spending the day with Netflix, you need less energy. If you have a fever, you need 7 percent more calories per degree of fever. If you are younger or older, you need differing amounts of energy. No food label can tell you what’s going on with you.

Here are a few tips to better listen to your body’s signals of hunger and fullness:

  1. Strive for balanced. Make sure to include a variety of macronutrients (carbs, proteins, and fats) on your plate at every meal and snack.
  2. Don’t deny yourself foods that you want. Eat them with joy and enjoyment. The calorie-counting mentality includes a lot of guilt and shame, which can actually lead to overeating with reduced enjoyment.
  3. Eat quality foods that you truly want. Craving a donut? Get a good one. Eat it slowly and focus on the tastes, sensations and smells. Chances are you’ll be satisfied with a normal portion.
  4. Learn to forgive yourself. Overeating foods you rarely have or at special meals is normal, it’s not the end of the world. Remember that your body is well equipped to handle variation in intake.

The more you can respect and respond to your body’s signals of hunger and fullness, the more you will come to trust them. As we are more and more saturated by calorie information, this skill will become useful, allowing you to eat the foods you enjoy without input from the menu board. It doesn’t know what you need.