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Understanding Calories In vs Calories out.

By Coach Alysha Mears

Have you heard the term Calories in vs Calories out?

Did you know that the amount of energy you expend each day vs the amount that you consume is the main determining factor of weight gain, loss or maintenance?

Calories = energy

We use calories when resting, sleeping, eating, exercising, working….ALL THE TIME.

The amount of calories you spend each day accounts for your Base metabolic rate (BMR) & activity expenditure.

Your BMR is the energy that is required for you to simply exist & function as you are.

To calculate this, We can take into account your age, weight, height, and lean body mass. To work out how much you require in total, after BMR is calculated we then account for how active you are to get the sum of your total daily energy expenditure.

There are different equations you can use to calculate your expenditure, however you can refer to the below Mifflin st Jeor equation below:

Males (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5.

Females (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161.

Not fantastic at Math? simply head to a calorie calculator online, although nothing will beat the value of chatting with a professional about your requirements first.

Once this equation gives you your BMR, you need to multiple by your activity level for your TDEE:

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SO...why do you gain fat if you consume more calories than you expend?

In human history, we have never had food as accessible as it is today (in Western culture). On top of this, we have never been as sedentary as we are today - with the majority of the population now working in office jobs or from home.

From an evolutionary standpoint, we have evolved to save energy more efficiently as a mechanism to avoid starvation (which up until maybe a 100 years ago was a genuine risk and our biggest threat other than disease or a virus).

Therefore, our bodies are built to conserve energy to last days without food BUT we do not live with the impending risk of starvation anymore, back to my previous point, food is more accessible than ever. Our bodies still only know to store our excess calories as fat in case it ever needs it!

How do you use your understanding of calories in vs calories out to lose fat?

In order to lose fat, you need to be in a caloric deficit (Eating less than maintenance caloric intake) - or in other words, Below your TDEE! (The equation we calculated above!)

You want your body to stop storing energy & instead, draw from the energy you have previously stored away.

Think of your daily caloric intake like a financial budget, you can pick and choose where you would like to spend your money.

You can make poor decisions with your money, like buying an expensive car that takes up a large chunk of your weekly pay. Technically you can afford it, but you have nothing left & you’ll live off two minute noodles and black instant coffee.

Calories are very much similar - technically, you can fit a donut or burger or some alcohol in your budget but it doesn’t leave a lot left.

So when it comes to fat loss the key is to come under budget for your calories which is much easier to do if you are eating whole foods, home cooked meals.

Diets such as keto, atkins, paleo, and intermittent fasting are not magical diets that make you burn fat - they are just restricted enough to put someone in a caloric deficit.

However, you don’t have to do any of these diets to lose weight. If you FEEL better on these diets and it’s sustainable… go ahead, but, you can be flexible & still enjoy the foods you love without restriction.

Personally, we take a flexible dieting approach and teach this to our clients because you already have a diet, you already have your favourite foods. For longevity & consistency it is best you learn how to fit these in.

What other factors should you consider?

Once you work out your TDEE, put yourself in a deficit (for fat loss), Baseline (maintenance) or surplus (gaining), the next step is allocate your macros. Calories are most important for weight loss, then Protein is second for maintaining muscle.

Carbs & fats can be eaten interchangeably but have individual benefits - so ensure you do get the minimum amount you require!

We will write a following blog on calculating your macronutrient targets, benefits of the three different macronutrients, flexible dieting & the common mistakes of caloric consumption!

Until then, if you need assistance? Or you’re not sure how flexible dieting can work for you?

Email us at and we will more than happily assist!

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