Calories In Vs Calories Out Explained

After years of diet experts swearing by calorie counting to lose, maintain and gain weight, we saw a big backlash when nutrition professionals started questioning the accuracy of the method. New macro-based, intuitive-eating and intermittent fasting diets took centre stage and the simple art of calorie counting was pushed out of fashion. But it seems we’ve come full circle and the old school ‘calories in vs calories’ out theory is once again the on-trend method favoured by fitness enthusiasts, with calorie-counting apps like MyFitnessPal becoming ever more popular.

What does ‘calories in vs calories out' mean? 

Very simply: 'calories in’ refers to food we are ingesting and the energy that it gives us, and ‘calories out’ refers to the energy we are expending through numerous actions including: breathing, sleeping, digestion, every day movement and of course through exercise. 

If we’re ingesting more calories than we burn…we will gain weight.

If we’re ingesting less calories than we burn…we will lose weight.

Why were people questioning its accuracy in the first place?

Some experts believe that calorie counting is done poorly and can be up to 25% inaccurate. Calories are also very often described and marked on packaging incorrectly. We also all consume different amounts of calories from food dependent on our intestinal bacteria, how our food is prepared, cooked and even chopped. Another factor worth highlighting is that people are often eye-balling their portion sizes, as apposed to measuring or weighing, which leads to massive inconsistencies in portion sizes.

Why are fitness professionals back on board?

For all its possible inaccuracies, calorie counting is still probably the best way we have to measure consumed energy and expended energy. No one was arguing the formula but rather the way we measured the calories. With the growing interest from consumers to know what’s in their food and government efforts to fight cardiovascular diseases and obesity, calorie counting is back in vogue. In fact, Dubai Municipality has passed legislation that instructs all food outlets to display calories on their menus by January 2020.

How do I know how many calories I should consume?

The best option is to get a professional to work this out for you, such as a personal trainer, as part of your goals. However, find included the Revised Harris-Benedict Equation that uses your BMR (Basal Metabolic Rate) and then applies an activity factor to determine your total daily calorie needs. The equation takes into account your height, weight, age and gender to calculate your BMR.


BMR- 88.362 + ( 13.397 x weight in kg ) + ( 4.799 x height in cm ) – ( 5.677 x age in years )


BMR- 447.593 + ( 9.247 x weight in kg ) + ( 3.098 x height in cm ) – (4.330 x age in years )

  • If you are sedentary (little or no exercise) : Calorie-Calculation = BMR x 1.2

  • If you are lightly active (light exercise 1-3 days/week) : Calorie-Calculation = BMR x 1.375

  • If you are moderately active (moderate exercise 3-5 days/week) : Calorie-Calculation = BMR x 1.55

  • If you are very active (hard exercise 6-7 days a week) : Calorie-Calculation = BMR x 1.725

  • If you are extra active (very hard exercise & physical job or 2x training) : Calorie-Calculation = BMR x 1.9 

Yeah, it’s not straightforward!

Can calorie counting work whatever my goal?

Manipulating the ‘calories in vs calories out’ figures to hit your goal is the most simple and effective way to get results. There are many other factors that come in to play, macro and micronutrients are important factors depending on whether you have a specific goal, be it muscle gain, lowering cholesterol or trying to eradicate type II diabetes, but the above theory still stands. 

It’s important to remember, you can eat all of the healthiest foods in the world, but if you consume more calories than your body needs, you will gain weight, simple. If weight-loss is your goal then a diet high in protein (which will keep you full longer) and is lower in calories per gram is advised:

  • 1g of carbohydrates contains 4 calories 

  • 1g of protein contains 4 calories 

  • 1g of fat contains 9 calories

Read next: Nutrition and Mental Health

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Devinder Bains