The Low-Down on Calories

The other day while the studio was buzzing with clients getting their sweat on, a conversation took place about calories. It quickly occurred to me that most people know they need to eat less and burn more calories, but they have no idea what a calorie actually is, where they come from, or how our bodies use them. So I dedicate this newsletter to all those unknown calories out there – it’s time for a little exposure!

What is a calorie?
This one’s pretty simple – a calorie is a unit of measurement. It describes the amount of energy that our bodies get from food. To determine calorie counts, a bunch of smart people get paid to burn food in a water-enclosed chamber called a bomb calorimeter (I swear there’s no quiz afterward). The number of degrees by which the burning food raises the water’s temperature equals the number of calories in the food. Have you learned something new yet?

How do we use calories?
To create the energy it needs, your body burns calories in a process called metabolism. Then it expends this energy in several ways. The amount used for basic functions (breathing, blood circulation) is known as the basal metabolic rate (BMR). Even if you sat on the couch all day, your cells would still draw on energy to function and it would account for 65 to 75 percent of your total calorie needs (no, this does not give you permission to sit on the couch all day). It might intrigue you to know that certain organs take more energy than others to function. Any physical activity, from walking around the house to attending boot camp sessions, consumes the remaining 15 to 25 percent.

Does it matter where calories come from?
It depends. Nutritionally speaking, the answer is YES! Food provides not just calories but nutrients like vitamins, minerals, and omega-3s. Also, the energy from the calories that fuel your body can mean the difference between gaining and losing pounds. Here’s how:

You’ve heard of carbohydrates, protein, and fat (macronutrients). For quick energy carbs are the way to go (hence marathon runners eating loads of ‘em). Your body breaks carbs down and converts them to glucose, it’s most prized energy source. It can break carbs down much easier than protein or fat, and your brain and nervous system run only on glucose, so you can see why it’s never a good idea to follow a no-carb diet 100 percent of the time. Fat, on the other hand, contributes energy for sustained activity, but some of the fat you eat goes into storage to be used later when, and if, it’s needed. Lastly, protein can provide energy, but it takes the most effort to convert (a good thing). Your body prefers to use it to build and repair tissue like muscle.

Now...as far as losing weight goes, protein generally makes you feel full longer and you’ll burn more calories metabolizing protein; high-fiber carbs make you feel full longer, too; and fats may possess a yummy texture and make foods taste delicious but they aren’t necessarily satiating. With that said, nobody – not even scientists – have agreed on whether emphasizing one of these over the other two helps people lose weight. The only thing anyone knows for sure is that you need nutrients from all kinds of food and the only diet you’ll lose weight on is the one you’ll actually stick to. Sorry, no weight-loss secrets here!

How do we burn calories?
Our bodies don’t like to waste calories, so it stores any unused energy as fat (helloooo, beer belly!). To lose fat, you need to expend more calories than you take in – 3,500 for each pound you want to lose. So if you have a deficit of 500 calories each day for seven days, you’ll lose one pound of fat. You can create that deficit by eating less, exercising more, or, my choice, doing both.

So...how many calories do you need?
Each day, your body requires enough calories to fuel basic functions plus all your activities. To calculate your needs, look for an online calculator that accounts for your height, weight, sex, age, and activity level. Try mayoclinic.com/health/calorie-calculator/NU00598. This will tell you how many calories you can eat each day to maintain your current weight. If you’re looking to lose weight, however, you need to burn 3,500 calories for each pound you want to lose (see above).

Now that you understand calories and how your body uses them – think about that 16 oz gingerbread latte the next time you go to order it, and remember how many times you’d have to run around a track to burn it off and reach your weight loss goal in time for the holidays!