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Calorie Calculation Basics

Calorie Calculation

Whether you're trying to lose weight or pack on muscle, you'll need to figure out how many calories to eat each day. You could just guess, make a few healthy eating choices, and probably get by with a moderate amount of progress, especially if you're a beginner. But in the long run, it's worth spending a few minutes calculating your caloric needs.

It's not a single-step process, but don't worry—we're going to walk you through every step.

Step 1: Choose an Equation

First, you need to decide how you want to calculate your calorie intake. There are several equations available, but here are some of the most well-known:

  • Harris-Benedict
  • Mifflin-St. Jeor
  • Sterling-Pasmore

For a good all-rounder that some research seems to support, we recommend Mifflin-St. Jeor, but it might be worth plugging the numbers into all of them and comparing the results. Here's the formula for Mifflin-St. Jeor:

  • Men: 10 x weight (kg) + 6.25 x height (cm) – 5 x age (y) + 5
  • Women: 10 x weight (kg) + 6.25 x height (cm) – 5 x age (y) – 161

Step 2: Calculate your BMR

BMR is short for Basal Metabolic Rate, the number of calories your body needs to function at rest. In other words, assuming you spend all day lounging on the couch, consuming this number of calories will allow you to break even.

Using the Mifflin-St. Jeor equation for a 75kg/180cm/30-year old man:

  • 1. Multiply your weight in kilograms by 10: 75 * 10 = 750
  • 2. Multiply your height in centimeters by 6.25: 180 * 6.25 = 1125
  • 3. Add those two numbers together: 750 + 1125 = 1875
  • 4. Multiply your age by 5 and subtract that number: 1875 - (30 * 5) = 1725
  • 5. Add 5: 1725 + 5 = 1730

Step 3: Adjust for your activity level

Calculating your BMR is a great start, but that number alone won't paint an accurate picture of your caloric needs. Assuming you're a normal person who does normal activities, you need to adjust for that extra work. Everything burns calories, even daily tasks that you don't even think about. Brushing your teeth? Calories. Carrying your laundry basket upstairs? More calories.

To adjust for activity level, multiply your BMR from the previous step by one of these numbers:

  • Sedentary: 1.2
  • Light activity: 1.375
  • Moderate activity: 1.55
  • High activity: 1.725
  • Very high activity: 1.9

If our man from the previous step was moderately active, his ideal calorie intake would be: 1730 * 1.55 = 2681.5.

Step 4: Adjust for your goals

At this point, some of you might be done. If your goal is to maintain your current weight, then you're good to go. However, if you're targeting a specific goal like weight loss or muscle gain, then there's one more step you need to take. -If you want to lose weight, subtract 300-500 calories. -If you want to build muscle, add 300-500 calories.

Wrap Up

Understand that this final number is a starting point. No equation is without flaws, and you can't perfectly match your activity level to a decimal value. Similarly, 300-500 calories in either direction might not be enough to make progress. You'll need to carefully monitor your progress and continue to adjust your calorie intake to fit your goals.