How to Calculate Your Calorie Needs (And Reach Your Ideal Weight Faster)

Weight Loss

When it comes to healthy eating or weight loss, many of us think about one thing: counting calories. While using an average estimate for caloric intake can certainly be a good ballpark to work with for starters, if you really want to have an effective weight maintenance or weight loss program, you’re going to need to make something more individualized.

In this case, that means calculating how many calories you should be consuming on a daily basis to meet your goals. But it shouldn’t only be about stepping on the scale, should it? It’s also important that you feel good while doing it. Otherwise, the chances of continuing it for the long-term are pretty low. Let’s look at the best ways to calculate your calorie needs, and how to reach your ideal weight quickly.

Why is Calculating My Calorie Needs Important?

While a “one size fits all” kind of recommendation is neat and easy, it does not take into account the fact that everyone’s body and lifestyle is completely different. Everyone knows that some people seem to be able to eat whatever and however much they want without gaining an ounce, while others diet and exercise and don’t seem to ever lose the weight they want to lose. This is because of those differences in our bodies. For that reason, it’s important to calculate our calorie needs individually.

Woman cutting up parsley on a cutting board on her kitchen counter filled with fresh fruits and vegetables

Imagine if all pants were just in the “average” size rather than being sized individually. While the term “average” implies that it should be good for most people, the truth is that very few individuals actually fit into that particular size and shape. It just wouldn’t work for everyone. The same applies to a calorie needs average.

You may have already heard that the average female should take in 2000 calories per day, while the average man should take in 2500 calories per day. This is if they would like to maintain their current weight. For losing weight, an average woman should theoretically take in 1500 calories, while an average man should take in 2000 calories – so 500 calories less per day. In terms of math and science, this should help a person lose one pound per week (since 3500 calories technically are equivalent to one pound of fat, and 500 calories x 7 days = 3500).

That said, how many people do you think this actually works for? There’s a reason so many people struggle to find a diet or nutrition plan that is right for them. That’s because the “one size fits all” diet plan simply doesn’t come close to fitting all people – it needs to be individualized. That’s where the calorie needs calculation comes in handy.

Think of all the differences in our bodies. The differences include how active we are, what our current age is, how tall a person is, what your current weight is, what your metabolic health looks like, what your medical history is, and so on. All of these affect your calorie needs as well.

Better yet, calculating calorie needs has a lot to do with your personal goals and preferences. Someone who simply wants to see what their benchmark is for maintaining their weight will find one number. On the other hand, someone who is determined to lose weight in a healthy way is going to find another kind of number. In addition to that, your calorie needs are actually going to change as you lose weight. That means that you need to continually recalculate the calorie needs as your weight drops, making the ability to calculate it individually all the more important.

What’s Up With “Calories” Anyway?

It may seem like an odd question since we’ve been hearing about calories since what feels like forever. But what are these calories all about? Have you ever wondered what calories actually are?

Simply put, a calorie is a unit of measurement, much like a pound, an inch, or a mile. In this case, however, calories measure energy in foods and drinks. There’s a reason everyone is so obsessed with calories – the key fact about calories is it more or less determines how much weight a person gains or loses. If you consume fewer calories than your body burns in a day, for example, you’ll start losing weight. If it’s the opposite, you’ll start gaining weight.

Male and female running partners on the beach holding measuring tapes around their waist

Of course, we already know that it is so much more complicated than just lowering the number of calories. The types of foods your eating is extremely important – even more important than the number of calories you eat, in fact.

This is why looking at weight loss and nutrition plans from a holistic standpoint is so important. Just cutting calories may not be doable for the long term unless you’re eating more nutritious foods to make up the remaining calories. This would just make a person feel hungry all the time, and that’s not what a healthy diet should be like.

Likewise, just eating nutritious foods isn’t going to help you lose weight if you’re not reducing the number of calories you’re taking in. There are a number of ways to alter your nutrition plan so that you can lose weight in a healthy way, including:

  • Increasing your protein intake
  • Stop drinking soda and fruit juices (or sugary drinks in general)
  • Increasing the amount of water you drink every day
  • Increase the amount of exercise you do
  • Lower the amount of carbs and sugars you’re taking in[1]

How Does Calorie Calculation Work?

There are a number of free calorie calculators that you can find online. Generally speaking, you fill in your relevant information (often with the option of adding more detailed information for a more specific calculation), and then it shows you what your daily caloric intake should be if you want to maintain your weight, lose weight, or lose extreme weight (not recommended).

Close-up of a slim woman's torso with a measuring tap held around it

Of course, it’s not quite that simple. Oftentimes it gives you a few more options, such as which formula you would like it to use. There are three formulas most commonly used: the Mifflin-St. Jeor Formula, the Katch-McArdle Formula, and the Harris-Benedict Formula.

Each of these formulas is actually designed to figure out the Basal Metabolic Rate, or the BMR. Essentially, the BMR is the number of calories (also known as the amount of energy) that your body uses up just by existing every day. It’s the same number as you would burn simply lying around throughout the day. You may have heard of this number before, but perhaps with a different name. It has also been called the Resting Energy Expenditure, or REE, or the Resting Metabolic Rate, or RMR.[2] Basically, this just means that the number you get with these formulas is only the starting point, rather than the end of the calculation. Nonetheless, let’s learn a little bit more about these formulas below.

Mifflin-St. Jeor Formula

This formula is largely considered to be the most accurate of the three formulas.[3] It applies best to an average adult. This uses the following calculations for men and women:

  • MEN: 10 x weight (kg) + 6.25 x height (cm) – 5 x age (years) + 5
  • WOMEN: 10 x weight (kg) + 6.25 x height (cm) – 5 x age (years) – 161

Katch-McArdle Formula

The Katch-McArdle Formula takes the above formula and includes fat-free mass, also known as lean mass. This applies best to someone who has lower body fat or is leaner. If you know your body fat percentage, this may be the best formula for you. You cannot do the formula without knowing that first. This uses the following calculations for both men and women:

  • 6 x Fat-Free Mass + 270

To calculate your Fat-Free Mass, do the following calculation:

  • Weight – (Body Fat Percentage x Weight)

Harris-Benedict Formula

The third and final formula commonly used to calculate your optimal daily caloric intake is the Harris-Benedict Formula. It is an older formula, going back nearly 100 years, and therefore usually comes up with a caloric intake that is roughly 5% higher than what is ideal for people today. This is simply due to the fact that we are, on the whole, more sedentary in our lifestyle than our ancestors were.

The following calculations are used for men and women:

  • MEN:5 + (13.75 x weight in kg) + (5.003 x height in cm) – (6.775 x age in years)
  • WOMEN:1 + (9.563 x weight in kg) + (1.85 x height in cm) – (4.676 x age in years)

Fun Fact: According to one study, the Harris-Benedict Formula is imperfect because it does not take your weight history or ethnicity into account.

The Next Step in Calculating Your Calorie Needs

It’s important to remember that, in the end, this is just a formula made by someone who has never met you and doesn’t know your particular circumstances. For example, the caloric needs of someone who exercises will be quite different from someone who doesn’t. Did you notice that none of the above formulas factor in your level of weekly exercise?

For that reason, someone calculating their own calorie needs should add an additional step after they use one of the above formulas. Assuming you don’t simply lie in bed day after day, you probably do more than only burn the Basal Metabolic Rate. Theoretically, if you did live a 100% sedentary lifestyle, this would be the number you should consume to simply maintain your current weight.

So, the number calculated above should actually be multiplied from 1.2 to 1.9, which completely depends on how physically active you are. The calculator factors this in automatically when you select your rate of weekly activity or exercise.

How Do I Calculate My Calories Needs for Losing Weight?

Young woman holding a green apple and smiling in her house

Now that you know how to calculate the calorie needs for maintaining your weight, how do you go about calculating it for losing weight in a healthy way? Once you have calculated the BMR and have multiplied it according to your daily or weekly activity levels, it’s time to figure out the right number for you to lose weight.

You can simply subtract 20% of that number to find the number of calories you can take in to lose weight. This keeps it at a good, moderate number that will ensure that you are losing weight without making your body go into shock, or make you feel hungry all the time.

Please note that, while the 20% is a good quantity to start with, you should never exceed reducing your calorie intake by more than 500 calories per day. So, if taking away 20% ends up taking away more than 500 calories, it is recommended that you only reduce it by 500 calories maximum, or else to get to that number on a gradual, daily or weekly reduction basis.

Fun Fact: Don’t forget about other factors for some people, such as if you’re pregnant. Pregnant women have an entirely different calculator they should use, since their caloric needs are completely different. Some weight gain is normal and healthy, but should be monitored closely.

What Could Go Wrong?

It’s important to remember that you absolutely need enough calories to fuel your body. Without them, you’ll feel terrible, you’ll lose too much weight too fast (which won’t stay off anyway if you start eating right again), and your body will start going into crisis.

If you are cutting down on calories too much, you will start losing muscle mass first and foremost. This occurs because your body looks for sources of calories, and quite a bit is stored in your muscles. After just a few days, your metabolism will slow down in order to compensate for the lack of calories and the muscle mass loss. You will start having nutrient deficiencies, you will feel tired all the time, and you may even become irritable and cranky on a consistent basis. None of this will be helpful in establishing a new, sustainable nutrition plan to lose weight. In other words: make sure you’re eating enough!

Summary: What Should You Do Now?

If you take anything away from this article, take away the fact that everyone’s body is different. What works for your friend or spouse may not work at all for you – and that’s okay! This is why the calorie calculations and other such individualized tools are so important. It may not sound as easy as a “one size fits all” kind of solution, but it’s far more effective and is therefore worth the extra effort.

So now that you have a better understanding how to calculate your calorie needs, it’s time to put this theory into action. Start by calculating your recommended calorie intake. You can do it with an online calculator or with the numbers and formulas written above – or maybe do both to ensure accuracy. Then, pick some nutritious foods that will make up the bulk of your caloric intake.

Calculate Your Calorie Needs (And Reach Your Ideal Weight Faster)

Action Steps: Tips for Reaching Your Weight Goals with the Calorie Calculation

  1. Calculate your recommended calorie intake with one of the above formulas.
  2. If your goal is to lose weight, subtract 20% from that number. This is how many calories you should consume per day.
  3. To lose extra weight, increase your amount of exercise – but be sure to recalibrate your calorie calculation once you start, so you get enough fuel for the extra activity.
  4. Swap sugary drinks, added sugars, and carbohydrates for proteins and fresh fruits and vegetables. Create a nutrition plan that is packed with nutrients rather than only “empty” calories.

A calorie calculation is a great way to start your healthy weight loss program off right. Be sure to pay attention to your body. If after a few weeks you start feeling fatigued or irritable, up your caloric intake. Your new nutrition plan should be sustainable, and that means you should feel good while doing it.


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