What is a calorie?
We hear it all over the place: “That cheeseburger has, like, a billion calories!” People who are trying to lose weight are often talking about how many calories something has, and how they’re counting them. But when even is a calorie, anyway?
If we want to be technical about it, a calorie is defined as “the amount of heat energy required to raise the temperature of 1g of water by 1ºC. Ummm, that’s not helpful. Let’s redefine it so it makes any sense at all.
A calorie is a measure of energy. The stuff in food creates a chemical reaction within our cells, and that reaction releases energy. We use that energy to do every day things – moving, breathing, digesting, even while sleeping. Most of us use somewhere around 2,000 calories worth of energy a day – hence, “A 2,000 calorie diet” is used on food labels, in commercials, you name it!
Calories are just a way to measure your energy intake and output. Want to calculate your own needs? I’ll show you how in this article: How to Calculate Your Calorie Needs
What calories are actually doing in your body
When we eat food, we can think of it as eating energy. Food = fuel! If we are moving around and using up a lot of energy, we find a balance between the energy we have eaten and the energy we have burned. If we eat more energy than we burn, our bodies will store some away. If we burn more than we eat, we use up our stores.
Let’s translate that:
We eat to consume calories. We need to find a balance between calories eaten and calories burned (through exercise and daily living). If you eat as many calories as you burn, your weight will stay the same. If you eat more calories than you burn, your body will store the extra calories as fat. If you burn more calories than you eat, your body will use up your fat (and muscle) stores for extra energy.
I feel like I sound like a broken record here. It makes sense, though, doesn’t it? Use it or store it!
Where do calories come from?
We know that calories come from food, but why are some foods low calorie, while others are calorie bombs?
Here I go again sounding silly: Food is made up of nutrients. There are six major nutrients – Carbohydrates, Protein, Fat, Vitamins, Minerals, and Water. Three of these are energy-yielding nutrients, meaning they provide calories. Carbs, protein, and fat yield energy, or contain calories. Vitamins, minerals, and water are free! Although they help with metabolic reactions in our cells to extract the energy, they don’t actually provide any themselves.
1 g carbohydrates = 4 calories
1 g protein = 4 calories
1 g fat = 9 calories
One gram of carbohydrate and protein are equal to four calories, whereas one gram of fat is equal to nine calories. On a food label, you will see how many grams of each of these macronutrients the item contains. From there, you can do the math to calculate how many calories there are!
BUT IT GETS EASIER!!! If there’s a food label, they’ve already calculated the calories for you! Sure, they may have rounded a bit (food labels allow up to 20% error on grams of nutrients and calories…but I digress), but it’s close enough to where you need to be, especially if you’re just starting out.
Related Reading: How to Read a Nutrition Facts Label
If a food doesn’t come with a label – like a piece of fruit or a vegetable – all you need to do is type “how many calories in an apple” into google and you’ll have your answer. There’s still some guesswork there, though, unless you know your portion size. This is where a kitchen scale comes in handy! A 100g apple is going to have fewer calories than a 180g apple. There are a ton of databases out there, but I prefer to use Nutritiondata.self.com to calculate how many calories are in a food!
Which foods are low calorie? High calorie?
Fat, as a nutrient, carries the most calories. A high fat food, like fatty cuts of meat, butter, whole milk, cheeses, avocado, coconut, olives, and baked goods are going to be higher in calories because they contain fat.
Carbs and protein contribute to caloric content, too. When we think protein, we think meat and beans. Carbs? Breads, grains, rice, cereals, fruits, and even milk!
“So, what does that leave? No food is safe from calories!”
That’s okay! You need calories – they aren’t evil like everyone makes them out to be. We just need to find balance.
That being said, fruits and vegetables are primarily water and lots of vitamins and minerals, with some carbs. They’re going to be your lowest calorie food, and packed with other great nutrients! Leaner cuts of meat (like choosing chicken breast over steak) will be a lower calorie choice, too.
Personalize it! Calculate Your Own Calorie Needs
Check out my article, How to Calculate Your Calorie Needs, to learn more about how many calories you burn in a day (just by existing!), how many you need to eat to maintain, gain, or lose weight, and how many calories are in a pound of fat!