How to Calculate Your Calories for Weight Loss

It seems like every week a new diet book comes out promising effortless weight loss. We’re told that we just need to jump on the low carb bandwagon or follow a Paleo diet to get in shape. But when it comes to weight loss, every diet works the same way—by creating a caloric deficit.

Research has found that the difference in weight loss between popular low-fat or low-carb diets is insignificant. This means that you can find a diet that works best for you. You just need to understand the basics of energy balance and how to reduce your calories to lose weight. Let’s look at how you can do this.

  Image source:  Myolean Fitness

Image source: Myolean Fitness

What Is Energy Balance?

Energy balance is the relationship between the energy (calories) we get from food and the amount used for our daily needs:

  • Positive balance: when you use fewer calories than you take in. A positive balance causes weight gain.
  • Negative balance: when you use more calories than you take in. A negative balance causes weight loss.
  • Neutral balance: when the calories you take in equal the amount used. A neutral balance allows you to maintain your weight.
  Image source: Pearson Education

Image source: Pearson Education

The energy balance equation is an oversimplification of weight loss. It doesn’t account for metabolic slowdown, hormonal changes, or mood. These are just a few of the factors that make weight loss challenging.

With that said, understanding the amount of food you are eating and how to make adjustments can go a long way towards helping you lose weight. Before we dive into this, here’s a quick recap of how your energy is used.

How Is Energy Used?

There are three main components that make up our daily energy expenditure:

  1. Resting metabolic rate: around 60-80% of energy is used for basic functions like breathing, contraction of the heart, and repair while at rest.
  2. Thermic effect of food: around 10% is used for digesting food.
  3. Physical activity: around 10-30% is used for moving around and structured exercise.

When we add the energy used for resting metabolic rate, thermic effect of food, and physical activity, we get our total daily energy expenditure:

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Once you know your total daily energy expenditure you can reduce the number of calories you’re eating to lose weight.

How to Calculate Your Total Daily Energy Expenditure

There’s a range of expensive options such as lab tests and body composition scans, but for our purposes, an online calculator works. Here are the steps to calculate your daily calorie needs:

  1. Add your details to this calculator to get your resting metabolic rate. This is the number of calories you need to maintain basic functions like breathing. The number does not include your activity levels.
  2. To factor in activity, multiply your resting metabolic rate from step 1 by the appropriate Harris Benedict Equation found here.

The number you get from step 2 is an estimation of the number of calories you need a day to maintain your current weight—your total daily energy expenditure.

How to Adjust Calories to Lose Weight

Now that you know your maintenance calories, you can reduce your intake to create a caloric deficit to lose weight.

To do this, cut your calories by 10-20%. Dropping your calories by more than 20% for a long time can cause metabolic slowdown and other issues. The 10-20% range is a safe and sustainable reduction.

Let’s look at an example of how this would work.

Weight Loss Example  

John is a 40-year-old male. He’s 6 foot and weighs 210 pounds. John’s resting metabolic rate is calculated as 2,016 calories per day using the above calculator.

Now, remember that the resting metabolic rate we calculated for John (2,016 calories) is the amount required for basic functions. We now use the Harris Benedict Equation to account for activity levels.  

John’s resting metabolic rate was 2,016 and he is moderately active, so the equation becomes 2,016 x 1.55 = 3,124 calories per day. This is the approximate amount of calories John will need to eat every day to maintain his current weight.

The final step is to reduce John’s maintenance calories by 10-20%, depending on the weight loss goal.

John wants to lose 20 lb quickly, so he decides to reduce his calories by 20%. This means he’ll be eating 2,500 (3,124 – [3,124 x 20%]) calories a day.

A safe and maintainable weight loss rate is around 1-2 pounds per week. There are approximately 3,500 calories in a pound of fat. So, if we create a daily calorie deficit of 624, John would lose around one pound per week. This does not factor in additional calories burned from exercise or account for metabolic slowdown.

How to Track Your Calories

Once you’ve reduced your calories, you’ll need a way to track what you’re eating. You can easily do this using free online apps like MyFitnessPal or FatSecret.

Even if you only do this for a week or two, it’s a valuable exercise. It’ll give you an idea of how much you’re eating and the calorie content of foods.

There are a few tips and tricks to help you track your food accurately, which I’ve covered in a follow-up post. For now, just make sure that the nutritional data is correct when you log food into the online apps. You can do this by cross-checking it against a site like this.

There’s More to Weight Loss Than Calorie Counting

Learning about your daily caloric needs is a good starting point, but it’s important to understand that our bodies are dynamic systems. Looking at weight loss solely from the perspective of ‘calories in, calories out’ misses many other important factors. Here are some resources that will help you lose weight and learn about optimising your health.

Do Something—Anything!

Don’t just consume information. If you’ve read this far, I’m assuming you find this post useful. You’ve now got two choices: 1) close the screen and think ‘that’s nice’ and move on with your day. Or 2) spend 10-minutes calculating your caloric deficit. Commit to a two-week trial of tracking your food, then you can try to make small changes to reduce your intake. As Nike says, just do it! Decision creates action. Action creates results.

I Need Your Help

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You can also share some love by adding a comment below. Let me know if you have any questions about setting up your calories for weight loss.

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