Every dieting plan is revolved around calorie intake and macronutrients. We adjust calorie intake based on our weight goal, but does weight loss rate depend on something else?

What are calories anyway and what do they represents?

One calorie is energy required for heating up 1 gram of water for 1°C. In everyday conversation calorie became synonym for kilocalorie kcal. You will often see nutritional value on the back of food packaging that is written in both kcal and kJ-kilojoule. 1 kcal = 4,2kJ

Calorie intake is individual and unique for every person. There are many ways of determining required calorie intake and they are based on calculations of basal metabolic rate (BMR) and physical activities during the day. One of the most precise methods is the Harris–Benedict equation (also called the Harris-Benedict principle) 

What is the basal metabolic rate and how it impact weight loss rate?

Basal metabolic rate or BMR is energy we spend resting (breathing, sleeping, digesting, brain and heart function…). Men have around 7% bigger BMR than women with the same weight.

For calculating BMR you need: weight, height, age

MEN (metric)	BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5
WOMEN (metric)	BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161

MEN (imperial)	BMR= 66+(6.2 x weight in pounds) + (12.7 x height in inches) –(6.76 x age in years)
WOMEN (imperial)	BMR= 655.1 + (4.35 x weight in pounds) + (4.7 x height in inches) – (4.7 x age in years)

For precise determination of calorie requirement physical activities needed to be included into calculation.

AMOUNT OF PHYSICAL ACTIVITIES	DAILY KILOCALORIES NEEDED
Little to no exercise	BMR x 1.2
Light exercise (1-3 per week)	BMR x 1.375
Moderate exercise (3-5 days per week)	BMR x 1.55
Heavy exercise (6-7 days per week)	BMR x 1.725
Very heavy exercise (twice daily, extra heavy workouts)	BMR x 1.9

For example, 21 years old woman, 175cm 70 kg, who works out 3 times per week.

BMR= (10 x 70)  + (6.25 x175) – (5 x 21) -161 = 1527,75  ≈ 1528 kcal   (BMR=1528 kcal)

1528 x 1.55 =2368.4 ≈ 2369 kcal daily

According to this calculation, she will maintain her bodyweight by consuming 2369 kcal per day. If she wants to lose a few pounds, she should drop down her calorie intake. That means, if she will consume 500 calories less, it would provide her to lose a pound of fat per week. This is considered a healthy way of losing weight.

Extremely low calorie deficit

Any extremely low-calorie deficit, that is more than 20% less than your basal metabolic rate, is dangerous for your health and it can slow down your metabolism.

Another way to lose 500 calories per day is to eat 250 kcal less and burn another 250 kcal through workout. That doesn’t include moderate activity that is included in your daily calorie needs as it is shown in the example, so you will have to burn 250 additional kcal through exercise (running, walking, swimming, biking etc.)