When it comes to achieving fitness goals, knowledge can be the difference between obtaining results and failure. One of the most important things one has to consider, whether their goal is to lose or gain weight, or even have adequete energy to overcome daily challenges, is the bodies energy requirement. Now there are many online tools that will give a rough estimate of a persons Basal Metabolic Rate (BMR) based on height and weight, however these are very generalized, and often do not consider ones daily activities or exercise.
In this article, I will share with you the formula for obtaining both BMR and Estimated Energy Requirements(EER), and also provide a real life example. Please note that you will need to have a person's Lean Body Mass (total weight minus body fat weight).
The formula is as follows:
Basal Metabolic Rate (BMR) = (21.56 x Lean Body Mass) + 370
Activity Calories (AC) = 0.1 to 0.9, with 0.1 being completely sedentary, and 0.9 being someone who is performing 2 or more hours of vigerous activity per day. Some examples of occupations with various scores: Teacher 0.3, Construction worker 0.6, College athlete 0.9. This number is then multiplied by the BMR to show calories burned by daily activity.
Thermic Effect of Food (TEF) = 0.1
Estimated Energy Requirement = BMR + AC + TEF
Exercise Adjusted EER = EER+calories burned during exercise.
Now, allo me to demonstrate how all of this works with a brief case study:
You have a client named Johnny. He wants to lose weight, but needs to know his calorie requirement to plan for his future weight loss. He weighs 104.5kg and has 25% body fat. Approximately 26kg of his body weight is fat (104.5kg x 25%= 26.125kg of fat). His occupation is a mechanic, whic gives him an activity score of about 0.4.
Step 1- Find Johnny's Lean Body Mass (LBM): 104.5kg - 26.125 = 78.375kg
Step 2 - Find his Basal Metabolic Rate (BMR): (21.56 x 78.375) + 370 = 2060
Step 3 - Activity Calories (AC): 0.4 x 2060 = 824
Step 4 - Add BMR + AC for TEF calculation in th next step: 2060 + 824 = 2884
Step 5 - Thermic Effect of Food (TEF): 0.1 x 2884 = 288.4
Step 6 - Find the Estimated Energy Requirement (BMR + AC + TEF): 2060 + 824 + 288.4 = 3172.4 KCal
Now we know how much Johnny has to consume in calories (KCal) to maintain his current weight based on his body composition and daily activities.
One additional factor to consider after the EER has been determined is exercise, because it is not accounted for in the above calculation. This is actually rather simple to figure out since we already have all the pertinent information that we need for his regular calorie requirements. If Johnny exercises for about an hour every day and during each session burns 600 calories, we would simply add these caloies to his EER number. Therefore, if Johnny has a caloric need of 3172, add in the 600 calories and you will get 3772 exercise adjusted energy requirement.
Because this number is what he is required to eat in order to maintain his current weight, we can now modify these numbers to decrease or increase weight depending on his goal. In this case, he would like to lose weight, so we would advise him to eat less than 3772 KCalories. He may be able to safely reduce his weight by 0.45kg per week if he reduces his calorie intake by 500 and only eats 3272 KCals per day, for example.