The Truth About Calories

We count them, cut them, burn them, obsess over them. Yet for most people, calories — what they are, how they affect us — remain a mystery. For instance, a 2009 poll of 1,000 people revealed that 70 percent were concerned about their weight, but only 11 percent knew how many calories they could eat each day without gaining.

A study from famed “mindless-eating” researcher Brian Wansink, Ph.D., of Cornell University shows that the bigger the meal, the more people underestimate the calories in it. It shouldn’t come as a surprise, then, that new research suggests eating too much — not exercising too little — accounts for the rise in obesity in our country. But there’s more to calories than the pounds they cause people to pack on. To help you better understand these tiny puzzlers — from how your body uses them to the impact they make on your health — we take a closer look.

What are energy-dense and nutrient-dense foods? Energy density may sound like a good thing — after all, we all want more energy. But in the food world, energy just means calories, so an energydense food is high in calories. Nutrient- dense foods, on the other hand, usually offer exactly what their name declares — lots of vitamins, minerals, and other good-for-you nutrients. Ideally, you want the majority of your foods to rank low in energy density but high in nutrient density. Say, for instance, you’re given a choice of a third of a Milky Way bar or a cup of blueberries. Both contain 84 calories, but you’ll get 19 percent of your daily vitamin C requirements from the blueberries, plus 14 percent of your fiber and important antioxidants. A candy bar can’t compete.

What is a calorie?
Back in science class, most of us learned the answer to this simple question: A calorie, like an inch, is a unit of measurement. It quantifies the amount of energy that our bodies get from food. To determine calorie counts, scientists burn food in a water-enclosed chamber called a bomb calorimeter; the number of degrees by which the burning food raises the water’s temperature equals the number of calories in the food.