The complete guide to calculating caloric needs

Undoubtedly, a successful diet will require smart planning. This includes calculating the daily caloric requirements, which differ from one person to another. The following could be used as a guide to achieve a rough calculation of daily caloric needs.

Basic Terminology:

• BMR (Basal Metabolic Rate): The amount of calories you need to consume in order for your internal organs to function at rest.
• NEAT (Non-Exercise Associated Thermogenesis): The amount of calories expended on daily activities that are not exercise-related (For example: working, doing house chores, shopping, etc.).
• EAT (Exercise Associated Thermogenesis): The calorie requirements associated with planned exercise.
• TEF (Thermic effect of feeding): The calorie expenditure associated with eating. This is considered as a percentage of total calories consumed. The percentage varies according to macronutrient and fiber content.
• TEE (Total Energy Expenditure): The total calories required. It is determined by the sum of the above (BMR + NEAT + EAT + TEF = TEE). 

Factors affecting caloric requirements:

A number of factors (in no specific order) are considered to have an impact on daily caloric requirements:

• Diet (What kind of food are you ingesting?)
• Daily activity level (Do you have a job that requires a lot of moving around?)
• Exercise level (More exercise = more calories required)
• Age and gender (Generally, males require more calories than females)
• Hormones
• Physiological status (Illness, injury, pregnancy, etc.)
• Total weight and lean body mass (More lean body mass = more calories required) 

Estimating caloric requirements:
This involves various methods which are different in terms of accuracy. Many of these methods were scientifically developed to ensure close-to-perfect results. The simplest method is to base the caloric requirement on a set of developed standards for “calories per unit of weight”. As a general guideline:

• Individuals with sedentary lifestyles and minimal physical activity:
• 26-30 kcals/kg/day (12.0-14 kcal/pound)
• Individuals involved in light to moderate activity 3-5 times/week with moderately active lifestyles:
• 31-37 kcal/kg/day (14-16 kcal/pound)
• Individuals involved in vigorous activity and highly active lifestyles:
• 38-40 kcals/kg/day (16-18 kcal/pound)
• Individuals involved in moderate to heavy training (15-20 hours/week):
• 41 to 50 kcals/kg/day (18.5-22 kcal/pound)
• Individuals involved in heavy to extreme training (more than 20 hours/week):
• 50 or above kcals/kg/day (more than 22 kcal/pound) 

Another method to estimate caloric requirements is to calculate BMR (Basal Metabolic Rate), which is the amount of calories required at rest (i.e. for the internal organs to function). A number of formulae could be used for that purpose:

• Harris-Benedict formula: This is the most inaccurate formula as many noticed that overestimates the requirements, especially for overweight individuals. Avoid it if possible.
• MALES: BMR = 66 + [13.7 x weight (kg)] + [5 x height (cm)] - [6.76 x age (years)]
• FEMALES: BMR = 655 + [9.6 x weight (kg)] + [1.8 x height (cm)] - [4.7 x age (years)]
• Mifflin-St Jeor: A more realistic formula than the previous one. However, it still lacks accuracy as it overestimates needs, especially for overweight individuals.
• MALES: BMR = [9.99 x weight (kg)] + [6.25 x height (cm)] - [4.92 x age (years)] + 5
• FEMALES: BMR = [9.99 x weight (kg)] + [6.25 x height (cm)] - [4.92 x age (years)] -161
• Katch-McArdle: The most accurate formula. The only set back is that you need to have a good estimate of your body fat percentage (BF%) to obtain a good estimate of your lean body mass (LBM).
• BMR = 370 + (21.6 x LBM)
• Where LBM = [total weight (kg) x (100 - BF%)]/100 

Notice that the formulae above will only provide you with BMR values. The next step here is to convert your BMR into your total caloric requirement (TEE), or what some like to call “maintenance”. This conversion is simple; you multiply your calculated BMR value by an “Activity Variable” to obtain your total caloric requirement (BMR x Activity variable = Total caloric requirement)

Activity variable:

The “activity variable” is the total cost of living. This involves your training as well as work, life activities, etc. Basically, you have to consider your activity level for a 24-hour period. These activity variables have been averaged into a set of values as follows: 

• 1.2 = Sedentary active (desk job + minimal physical activity) 
• 1.3-1.4 = Lightly active (light daily activity + light physical activity 1-3 days/week) 
• 1.5-1.6 = Moderately active (moderately daily activity + moderate physical activity 3-5 days/week)
• 1.7-1.8 = Very active (Physically demanding daily activity + Heavy physical activity 6-7 days/week)
• 1.9-2.2 = Extremely active (very heavy daily activity + athlete in heavy endurance training)

“I have calculated my total caloric requirement, now what?”
That’s it, the only thing you need to do now is to decrease or increase your caloric intake according to your goals (i.e. lose or gain mass). The right way to apply this customization is to consider the decrease/increase as a percentage of you maintenance, or total caloric requirement. Typically:

• To lose weight: Subtract 10-20% worth of calories from your maintenance.
• To gain weight: Add 10-20% worth of calories to your maintenance. 

If you stick to your maintenance for three weeks and notice stability in weight/measurements, then you have most likely found you maintenance. After determining your maintenance, you will need to monitor your results and adjust as required. Please keep in mind that the values obtained are rough estimates and are by no means accurate. Therefore, it will require a good deal of experimentation to achieve your goals. Good luck :)

Posted in: Health, Nutrition