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This question originally appeared on Quora. Answer by Wilfred Paul, 6 years of personal training, weight loss coaching with over 200 clients.

In order to be able to lose weight effectively it is vital to understand the importance of calories and how to calculate the amount of calories required for your body to lose weight. In weight loss, your diet plays 80 percent responsible for achieving the desired results.

Most people are engaged in different weight loss programs with the hope of losing weight. But, have you ever stopped to ask yourself what is it that helps people to lose weight in the first place? The simple answer is: "calories you take in versus the calories you expend." For you to be able to calculate and effectively burn the calories to lose weight, you need to understand what calories are.

What are calories?

In nutrition, calories are defined as the unit of energy that is obtained from foods and drinks. Your body cells need the calories to function normally and that is why you need to ensure that you meet your daily calorie intake. What you need to understand is that any food item that contains calories has the potential to increase your energy intake. Now, people who don’t understand the importance of calories in the body end up gaining or losing more weight than they intended.

To be able to understand the dynamics of weight loss and weight gain, you need to understand what the calories are and what their role is in their body. Calories, as mentioned above, are units of energy. They are the ones that provide the body with energy for its normal functions. However, the calorie intake is directly linked to the energy expenditure. This means that for you to be able to lose weight, the energy expenditure needs to be higher than the calorie intake. To gain weight, you need to maintain a higher energy intake than the energy expenditure (i.e. eat at a caloric surplus.) The opposite is true if you want to lose weight wherein you must burn more than you take in.

How calories are distributed?

As you know, there are three major macronutrients of food: carbohydrates, proteins and fats. For you to be able to effectively calculate your daily caloric intake, you need to focus on understanding the caloric make up of each of these macro nutrients. However, not all calories are created equally. Below is the number of calories per gram of each macronutrient.

Calories per 1 gram

Protein - 4

Carbohydrate - 4

Fat - 9

Alcohol -7

How many calories should I eat to lose weight?

Now we get down to the business end. This is where most people lose their way as they don’t have the sufficient knowledge regarding their recommended caloric intake to navigate toward their weight loss goals. There are three main steps to determine your caloric needs for weight loss.

  • Step 1 | Calculate your Basal Metabolic Rate (BMR)

When you are calculating your recommended caloric intake for weight loss, you need to factor in your age, physical activity, height, and weight. All these variables will impact your BMR. As mentioned in my previous post on The 5 Most Effective Ways to Boost Metabolism and Burn Fat, Basal Metabolic Rate (BMR) refers to the amount of energy that your body needs to run its normal functions. You can calculate your BMR by clicking on the link and accessing the calculator here.

  • Step 2 | Determine Activity Factor

Once you have figured out your BMR, the next step is to multiply it with the number that corresponds with your activity level per day to determine your maintenance calories.

Activity Level

Sedentary: Doing nothing strenuous all day. No exercise. 1.2

Lightly Active: Desk job. Works out one to three times a week. 1.375

Moderate: Desk job. Works out three to five times a week. 1.55

Active: Desk job. Works out six to seven times a week. 1.725

Very Active: Physical job (e.g. labour). Works out six to seven times a week. 1.9

Let take my numbers as an example:

BMR: 1895 calories (based on age 25, 182 centimeters, 80 kilograms, male)

Activity Level: 1.725

Daily Caloric intake to maintain weight at current level of activity is: 1895 x 1.725 = 3268 calories

Once we have figured out our maintenance caloric intake per day, we simply need to subtract the necessary calories from our diet to achieve our weight loss target.

  • Step 3 | How many calories to subtract?

To burn off 1 pound of fat = 3500 calories. Therefore, by deducting 500 calories from our calorie intake per day, we can burn of 1 pound of fat in one week (500 x 7 = 3500). This method is equally effective if we want to gain muscle too. We need to add 500 calories to our diet to create a surplus, which enables us to build muscle.

In this way, adding and deducting calories from our maintenance calories can help us gain muscle or lose weight more effectively.

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