Calories: Do They Count?

I hope you all had a wonderful Thanksgiving holiday. No doubt, you enjoyed some familiar favorites: turkey, stuffing, gravy, potatoes…perhaps a slice of pie. And you probably thought, at least a little bit, about how much you were eating (certainly important if you have diabetes), and you may even have wondered about how many calories you consumed. According to an article that I read on The New York Times Web site, the average Thanksgiving Day calorie intake is 4500, which is equal to eating seven Burger King Whoppers. Wow!

What are calories?
I think most of us would agree that 4500 calories is a lot. Consider that a moderately active man needs, on average, about 2400–2800 calories per day to maintain his weight, while a moderately active woman needs about 2000–2200 calories a day. Of course, calorie needs vary from person to person, depending on a number of factors.


What are calories, anyway? Calories are a unit of measurement indicating how much energy we get from food. Only three nutrients in food contain calories: carbohydrate, protein, and fat (vitamins and minerals have no calories). Alcohol contains calories too, but it’s not a nutrient. Carbs and protein have 4 calories per gram, fat has 9 calories per gram, and alcohol has 7 calories per gram.

We all need calories. Calories indicate how much fuel the body has to do things, like walking, raking leaves, and even sleeping. But keeping calories in check requires a balancing act between knowing how much to consume (meaning, how much food to eat) and how much to burn off. If you’re trying to lose weight, it makes sense that you would need to either take in fewer calories or burn off more calories, or ideally, do both.

How many calories do you really need?
As part of my training to become a dietitian, I learned about various ways to calculate a person’s calorie, or energy, needs. There are a lot of formulas and calculators out there that can help figure this all out. So, I learned about total energy expenditure, resting metabolic rate, and activity factors. There are scientific ways to determine a person’s calorie needs, which involve using a calorimeter (in which a person is placed inside a structure that measures how much heat he produces), a metabolic cart, or a newer device called the MedGem, which measures airflow and oxygen consumption.

Fortunately, there are simpler and less technical ways to figure out calorie needs. Some of the formulas that dietitians use include the Harris-Benedict equation, which was developed in 1919, and takes into account age, gender, weight, and height, and more recently, the Mifflin-St. Jeor equation (which takes into account the same factors but is believed to be more accurate than Harris-Benedict). These equations also account for activity levels, which makes sense. If you’re very active, you’ll need more calories than a sedentary person to maintain your weight. You can then determine how many calories you’d need if you wanted to lose weight. If you’re interested, Google either of these equations to find online calculators to help you do this.

However, if you’re not a dietitian and just want to know of a quick and easy way to figure out your calorie needs, my suggestion is to check out the calorie table from the 2010 Dietary Guidelines for Americans. Or, if you don’t mind a little bit of math, you can use the formula of 25 to 30 calories per kilogram of body weight for weight maintenance. To convert pounds into kilograms, divide the pounds by 2.2. For example, a woman who weighs 130 pounds is 59 kilograms (130 divided by 2.2). If you want to know how many calories you need to lose weight, use 20 to 25 per kilogram of body weight. To gain weight, use 30 to 35 calories per kilogram.

Is calorie counting the way to go?
It’s fine (and maybe even a little fun) to figure out how many calories you need to lose, gain, or maintain your weight. But frankly, most people don’t count calories all that much. After a while, it can get a little tedious. In theory, calorie counting is easy. You figure out how many calories you need, and then you read labels, look at a calorie chart, or use a smart phone app to see how many calories is in that Starbucks latte or Burger King Whopper.

But it’s not that easy. Most Americans have no idea how many calories they need, and if they do, they don’t count calories all that accurately. That’s because an accurate calorie count involves tracking every morsel of food you eat and every sip of beverage that you take. If you’ve ever tried to keep a food record, you know how challenging it is to be thorough. Also, the bigger the meal you eat, the less accurate you’ll be at counting calories. And think of how hard it is to figure out the calories in a plate of lasagna or Chinese food, for example. By the way, dietitians aren’t even all that great at counting calories. In one study, when 200 dietitians were asked to figure out the calories in five different restaurant meals, most of them underestimated the calorie content by a lot!

We’ll look more at the fascinating world of calories next week. In the meantime, your assignment for this week is twofold: Use one of the calorie estimation methods that I mentioned to figure out your calorie needs, and then keep track of your calorie intake for a couple of days. Report on how you did and what was helpful or not. There are no right or wrong answers here, by the way. Experiment a little and see what you find out.

More next week!

Learn more about the health and medical experts who who provide you with the cutting-edge resources, tools, news, and more on Diabetes Self-Management.
About Our Experts >>