How Exactly Do Calories Work?

by Fit Body Team in Recipes + Nutrition

Chances are you’ve heard of calories. But what are they exactly?

Basically, you can think of calories as a unit of energy. Everything you eat contains calories, which in turn provides the fuel to power your body. 

How Many Calories Do You Actually Need?

Everyone has a unique daily caloric need. The amount of calories you need is determined by four main factors: basal metabolic rate (BMR), thermic effect of food (TEF), non-exercise activity thermogenesis (NEAT) and exercise activity thermogenesis (EAT). 

BMR accounts for the majority of calories burned and it can help determine how many calories you actually need. Requirements will vary per person depending on factors such as height, weight, age, and gender, but strength training is one way you can impact your BMR. The more muscles you have the higher your BMR will be because muscles burn calories even when they are at rest.

The second most important component that determines how many calories you need is NEAT. NEAT encompasses pretty much everything you do throughout the day that isn’t sleeping, eating or actively working out. For example, that means anything from fidgeting or taking the stairs to walking the dog or doing yard work.

Is There a Formula to Figure Out What You Need?

There are a few formulas that take the above factors into account to help determine how much you actually need to eat in a day, says Kylie Morse, Fit Body’s in-house Registered Dietitian. 

The gold standard for determining energy needs is through indirect calorimetry, which measures someone’s energy expenditure through gas exchange (our breath). This method is typically administered at doctors’ offices and select gyms. 

The next best measure is through a body composition test such as a DEXA scan (dual energy x-ray absorptiometry), which calculates estimated energy expenditure based on an individual’s true body composition.

There are more easily available methods online such as the Harris-Benedict Equation (which is the formula we use in the Fit Body app macro calculator) or the Mifflin St. Jeor Formula. And while the calculations are backed by research, they will never take into account the differences between individuals, according to Morse — and are therefore just estimations of your caloric needs.


What is a Caloric Deficit?

First, we need to talk about caloric maintenance. A caloric maintenance is the amount of calories you need to eat in order to maintain your current body weight. A caloric surplus is eating more than your maintenance and is how you gain weight. A caloric deficit is eating less than your maintenance, and is how you lose weight. A standard caloric deficit is 500 calories less than your maintenance. So for example, if your maintenance is 2,300 calories, your deficit is eating 1,800 calories a day. More than a 500 caloric deficit is not recommended since this is where it can become not only unsustainable, but unhealthy and can impact your hormones, metabolism, and even your menstrual cycle. 

Do I Need To Be in a Caloric Deficit for Weight Loss?

Why would you want to be in a caloric deficit? Well, if your goal is to lose weight, you’d want to burn more calories than you’re consuming. 

But not all calories are created equal. The distribution of macronutrients and the quality of food you eat plays a role in your overall health and physical goals, according to Morse. 

“For example, if you are eating in a calorie deficit but not getting enough protein, you will see weight loss but you won’t be able to maintain your hard-earned muscle mass which gives someone a strong, lean physique,” Morse states.

How Can I Cut Back on Calories Without Sacrificing the Foods I Love?

It’s important to find a way to slowly cut down on calories in a way that still serves your needs and doesn’t leave you feeling deprived. Rapid weight loss is unsustainable and can actually lead you to gain more weight back in the long run. A better idea is to figure out small, realistic steps to make healthy swaps that trade empty calories for nutrient dense foods that fulfill your macro needs. 

Here are some easy ways you can cut back on calories without cutting back on food:

• Love soda? Try slowly cutting down and opt instead for sparkling or spring water. Add some fresh sliced berries, mint or citrus to your water for a fresh twist.
• Establish healthier BBQ habits like putting mustard or sriracha on your burger instead of ketchup which has almost 4 grams of sugar per tablespoon.
• If you’re a sugar fiend when it comes to your morning coffee, consider a sugar alternative like Stevia or Monkfruit for the same taste without the excess sugar and calories.

While the amount you exercise will change your calorie needs, we don’t recommend relying on workouts solely to lose weight. Why? Because it’s tough to create a significant calorie deficit through exercise. And you may end up ravenous afterwards! Instead, rely on workouts to build muscle and get strong.

And of course, once you’ve lost weight, use Fit Body’s macro calculator to determine your new maintenance calorie and macro needs.

So, Where Do You Go From Here?

It’s best to avoid any programs or persons that advocate for a one size fits all approach. As previously mentioned, there are so many different factors that contribute to someone’s daily calorie needs. Any program that shares one broad caloric target will likely set you up for failure.

A program like Fit Body determines your calorie and macro needs by pairing your goals and personal statistics with a customized and sustainable plan for weight loss, maintenance or weight gain. In fact, the meal plans in the app are even tailored to your personal calorie needs!

But it’s important to note that not everyone can or should track calories, especially those with a past or present ED, and that’s totally ok!

Ultimately, focus on nutrients, not just calories. Yes, being in a caloric deficit is what will determine fat loss but the quality of those calories and balancing them with foods you enjoy is the key to losing weight in a healthy, sustainable way.

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