Counting calories is time-consuming and prone to errors — human or otherwise. Plus, calorie needs can differ by hundreds of calories even between two people of the same age, gender and weight.

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ON NUTRITION

Do calories count? To what degree? It’s useful to know that a cup of broccoli has fewer calories than a cup of rice, and that we use up more calories walking than sitting, but when we meticulously track our calories in and calories out, then feel secure in the final tally, are we just kidding ourselves?

Keeping a food record is an effective way to build awareness of your overall eating pattern, because often you might think you remember exactly what you’ve eaten when actually you don’t. Food-tracking apps can be a convenient way to keep track, but research suggests we shouldn’t put too much faith in the numbers part, for a few reasons:

• Your “medium apple” might not really be medium-sized.

• Calories listed in restaurant menus may be “good guesses” at best, in part because you might be served an amount that’s slightly more — or slightly less — than the portion size that was analyzed.

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• For some foods, the number of calories listed on the food label or in nutrient databases may not be accurate.

For more than 100 years, calorie counts have been based on the “Atwater factors,” a system developed in the 1890s by Wilbur Atwater, based on his experiments investigating how many calories we actually metabolize and absorb from food. That’s where the estimates of 4 calories per gram of protein and carbohydrates, and 9 calories per gram of fat came from. “All of the calories on food labels are probably from Atwater factors,” said David Baer, a research physiologist with the U.S. Department of Agriculture’s Human Nutrition Research Center in Beltsville, Md.

It appears that the Atwater factors may not be as accurate as was once thought. Take nuts, for example. Baer is the co-author of three recent studies re-evaluating how many calories we extract from nuts. It turns out that almonds have 23 percent fewer absorbable calories than thought, walnuts have about 21 percent less and pistachios have 5 percent fewer calories. This has to do with the fact that nuts are from plants, and plant foods have cell walls that the body must break down in order to digest and absorb the fat and other nutrients inside.

This could be one reason why research studies have repeatedly shown that eating nuts are not only heart-healthy but are not associated with weight gain, Baer said. “I think it’s a combination of reasons,” he said. “We’re probably getting fewer calories than we think. They’re high in protein, high in fiber. There’s something about chewing them that seems to be satiating.”

Atwater also didn’t take into account that the effects of cooking and processing matter. Cooking lets us pull more calories from starches and proteins. This means we absorb more calories from peanut butter than we do from whole peanuts, more from well-done steak than rare steak.

“Clearly there are some foods where the Atwater factors don’t work very well,” Baer said.

He said the next foods he would like to look at are whole grains and legumes (beans, lentils, peas). Previous research has found that the Atwater factors overestimate how many calories we get from high-fiber diets, but until Baer’s team looked at nuts, no one had been able to isolate calories obtained from one food from our overall diets. “I wouldn’t expect a 20 percent difference between the energy values because they aren’t high in fat,” he said. “But we’re dealing with fiber, and it’s always been somewhat of a question, how many calories do we absorb from fiber?”

Calorie needs can differ by hundreds of calories even between two people of the same age, gender and weight — the three factors used to estimate calorie requirements. Why such differences? The gut microbiome is one likely reason, since the population of microbes in your intestines affects how many calories you pull from your food. Eating out of sync with your circadian rhythms (i.e., eating at night) also can affect how we metabolize food. Even how we chew makes a difference.

The bottom line is that counting calories is time-consuming and prone to errors — human or otherwise. For example: “My Fitbit said I had 200 more calories left, so I had an evening snack … no, I wasn’t actually hungry.” When you are trying to eat portions of food that are compatible with what your body needs, your efforts are better spent looking inward:

• Choose foods that satisfy. Fiber and protein help with satiety, and so do nutrient-rich foods. Nuts fill the bill on all three counts.

• Build appetite awareness. Are you hungry? Satisfied? Too full? Knowing how your body feels when it needs food and when it’s had enough food is easier if you are mindful. When you make eating decisions on autopilot or while distracted (or based solely on calories), you aren’t tuned in to what you and your body really need.

• Cook more at home. Most restaurant meals are high in calories, and not just at chain restaurants. Start with this recipe.

Toasted Walnut, Quinoa, Kale Salad and Lemon Vinaigrette

Serves 6 as a side dish

Ingredients:

1 cup quinoa

1 1/2 cups water

1 tablespoon chopped thyme

1/2 cup chopped California walnuts

1 teaspoon virgin olive oil

1/2 cup julienned kale

1 tablespoon chopped dill

1 tablespoon chopped Italian parsley

2 tablespoons sliced green onions

1 tablespoon finely grated Parmesan

1 teaspoon salt or to taste

For the Lemon Vinaigrette (makes 1/2 cup):

2 tablespoons fresh squeezed lemon juice

6 tablespoons extra-virgin olive oil

Directions

1. Rinse quinoa under running water in a strainer.

2. Add quinoa, water and thyme together in a pan, bring to a boil; then reduce heat to a simmer and cook for approximately 20 minutes. When cooked, remove from pan and spread on a pan to cool in refrigerator.

3. Coat chopped walnuts in olive oil and either toast until golden brown in a saute pan on the stove or brown in the oven.

4. Combine cooked quinoa with all of the remaining ingredients. Mix with enough lemon vinaigrette to lightly coat ingredients.

(Recipe courtesy of California Walnuts)