What’s in a Calorie?

We hear a lot about calories these days, talk of empty calories and high-calorie foods. But what do we really know about them? We know we don’t want them piling up on our waists, but what else? Since we take in calories every day through our food and drink, it is high time we educate ourselves a bit on the subject. Learning a little more about nutrition can be a big step in living a healthier life.

For those of us who are not scientifically inclined, let’s start off with the basics. Did you know that a calorie is not specifically related to food? It’s true! A calorie is actually a measure of heat or energy. Specifically, the amount of energy, or heat, it takes to raise the temperature of 1 gram of water 1 degree Celsius (1.8 degrees Fahrenheit).[1] Basically, in the nutrition world, a calorie is energy from food.

But the calories in our diet are a little different. That’s because when speaking about nutrition and diet, the term ‘calorie’ is actually used to mean ‘kilocalorie’.[2] Technically speaking, a kilocalorie is 1000 calories, just like a kilogram is 1000 grams. This means an apple, which nutritionally contains around 70 calories, actually contains 70,000. However, for the remainder of this article, we will stick with the common, nutritional usage of the word ‘calorie’.

What makes a calorie?

The three main sources of calories are carbohydrates, protein, and fat. One gram of carbohydrates or protein contains 4 calories, while one gram of fat is much more calorically dense and contains 9 calories.[3] Perhaps it goes without saying, but this is the reason fatty foods tend to cause weight-gain. In a healthy diet, we want to have a good balance of these three nutrients. Carbohydrates should make up around half to two-thirds of your calorie intake.[4] The rest is a mix of fats and proteins. Make sure to focus on getting healthy fats and proteins.

There are many resources available to check the calories present in the foods you eat. Calorie content is generally given for different serving sizes, as well as different cooking methods. Knowing how many calories are in your different food items will help you make smarter choices in your diet. caloriecount.about.com gives some easy to use nutritional information, as well as giving foods a grade nutritionally. Another good resource is calorie-charts.net; besides providing the average calories a food contains, it provides a breakdown of the calories coming from fat, carbohydrates, and protein.

Calorically dense?

When speaking of calories, it is important to recognize the quality of the source. Many of us consume far too many ‘empty calories’, which tend to come from fat and sugar. The reason they are called ‘empty’ is that they contain a lot of energy (calories) with very little nutrition. A short list of foods chock-full of empty calories reads like a “Who’s Who” list of the junk food world. Cakes, cookies, sweets, pastries, chips, French fries, cheese, butter, cream, lard, many meats, white flour, sodas, and alcohol all have the distinction of providing a lot of energy while being ‘empty’ nutritionally.

So what foods should we eat to get good, nutritious calories? Well, besides avoiding junk food, there are several simple changes we can make to improve the quality of our calories. First, it’s important to drink water. Just cutting sugary beverages from your diet will make a big difference in your caloric intake. Switch from white to brown rice, whole grain bread and whole grain pasta and make sure you eat lots of legumes (beans and peas), fruits, vegetables and some nuts daily. These foods contain lots of fiber, which is important for good health. As a bonus, fiber will make you feel fuller, which will keep you from overeating.

Counting calories?

So how many calories do you need in a day? The amount of calories a person needs can differ substantially from the standard 2,000 calorie diet listed on nutrition labels. Some people burn more and some people burn less. Many factors affect this process including height, weight, age, gender, and physical activity level. To approximate how many calories your body needs, you’ll need to calculate your basal metabolic rate (BMR) and then calculate your daily activity. Fortunately, there are many calculators online which make this easy to do, like this one.

For those watching their weight, There are a few things to be aware of. First, one pound of fat is about equal to 3,500 calories. Basically this means you need to burn 3,500 calories to lose a pound. So if you decided to cut 500 calories out of your diet a day, you would theoretically lose a pound a week. However, the actual weight-loss may be a bit less, because water and lean tissue are usually lost along with the fat.[5]

Basically, weight-loss is a combination of healthier diet choices and physical activity. We need to take a two-fold approach. First, we limit the number calories we take in, by eating healthier foods, avoiding fats, and limiting our portions. Second, we can burn more calories by increasing our physical activity. Walking, working out, or even doing chores around the house are good ways of doing this. It’s a simple, effective, and sustainable weight loss solution.[6]

So calories are actually pretty simple. They are not something that should stress us out if we stick to a healthy, balanced diet, full of fruits and vegetables. Train yourself to make better choices in regards to calories and it will soon become second nature.

[1] “Calorie (unit of Measurement) — Britannica Online Encyclopedia.” Encyclopedia Britannica.

[2] Ibid.

[3] “Macronutrients: The Importance of Carbohydrate, Protein, and Fat.” McKinley Health Center, March 26, 2008.

[4] Ibid.

[5] “Counting Calories: Get Back to Weight-loss Basics.” Mayo Clinic.

[6] Ibid

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Jon Ewald, MD

Jon Ewald grew up in Minnesota and has a love for the outdoors. He obtained his medical degree at Loma Linda University, graduating in 2020. He is currently completing his residency in Radiology at University of Pittsburgh.

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