The simplest method is to base your intake on a standard 'calories per unit of weight (usually kilograms)'. Typically:
- 26 to 30 kcals/kg/day for normal, healthy individuals with sedentary lifestyles doing little physical activity [12.0-14 kcal/pound]
- 31 to 37 kcal/kg/day for those involved in light to moderate activity 3-5 x a week with moderately active lifestyles [14-16 kcal/ pound]
- 38 to 40 kcals/kg/day for those involved in vigorous activity and highly active jobs [16-18 kcal/ pound].
For those involved in HEAVY training (eg: athletes) - the demand is greater:
- 41 to 50 kcals/kg/day for those involved in moderate to heavy training (for example: 15-20 hrs/ week training) [18.5-22 kcal/ pound]
- 50 or above kcals/kg/day for those involved in heavy to extreme training [> 22 kcal/ pound]
There are then a number of other formula which calculate BMR. This means it calculates what you need should you be in a coma.
1/ Harris-Benedict formula: Very inaccurate. It was derived from studies on LEAN, YOUNG, ACTIVE males MANY YEARS AGO (1919). Notorious for OVERESTIMATING requirements, especially in the overweight. IF YOU CAN AVOID IT, DON'T USE IT!
MEN: BMR = 66 + [13.7 x weight (kg)] + [5 x height (cm)] - [6.76 x age (years)]
WOMEN: BMR = 655 + [9.6 x weight (kg)] + [1.8 x height (cm)] - [4.7 x age (years)]
2/Mifflin-St Jeor: Developed in the 1990s and more realistic in todays settings. It still doesn't take into consideration the differences as a consequence of high BF%. Thus, once again, it OVERESTIMATES NEEDS, ESPECIALLY IN THE OVERWEIGHT.
MEN: BMR = [9.99 x weight (kg)] + [6.25 x height (cm)] - [4.92 x age (years)] + 5
WOMEN: BMR = [9.99 x weight (kg)] + [6.25 x height (cm)] - [4.92 x age (years)] -161
3/Katch-McArdle:Considered the most accurate formula for those who are relatively lean. Use ONLY if you have a good estimate of your bodyfat %.
BMR = 370 + (21.6 x LBM)Where LBM = [total weight (kg) x (100 - bodyfat %)]/100
As these are only BMR calculations To convert BMR to a TOTAL requirement you need to multiply the result of your BMR by an 'activity variable' to give TEE.
The Activity Factor is the TOTAL cost of living, NOT JUST YOUR TRAINING. Think about it - if you train 1 hr a day - WHAT ARE YOU DOING THE OTHER 23 HRS?! So MORE important than training -- it includes work, life activities, training/sport & the TEF of ~15% (an average mixed diet).
Average activity variables are:
1.2 = Sedentary (Desk job, and Little Formal Exercise)
1.3-1.4 = Lightly Active (Light daily activity AND light exercise 1-3 days a week)
1.5-1.6 = Moderately Active (Moderately daily Activity & Moderate exercise 3-5 days a week)
1.7-1.8 = Very Active (Physically demanding lifestyle & Hard exercise 6-7 days a week)
1.9-2.2 = Extremely Active (Athlete in ENDURANCE training or VERY HARD physical job)
How Accurate are they?: They give rough ball-park figures and are still 'guesstimations'. So the aim is to use these as 'rough figures', monitor your weight/ measurements for 2-4 weeks, & IF your weight is stable/ measurements are stable, you have likely found maintenance.
Using the Above to Recalculate Based on Goals
You then need to DECREASE or INCREASE intake based on your goals (eg: lose or gain mass). It is not recommended to use a 'generic calorie amounts' (eg: 500 cals/ day). Instead this should be calculated on a % of your maintenance. Why? The effect of different calorie amounts is going to be markedly different based on someones size/ total calorie intake. For example - subtracting 500 cals/ day from a 1500 total intake is 1/3rd of the total cals, where 500 cals/ day from 3000 total intake is only 1/6th of the total. The results will therefore be markedly different on an individuals energy level & weight loss. Generally:
- To ADD weight: ADD 10-20% calories to the total above
- To LOSE weight: SUBTRACT 10-20% calories from the total above
Then monitor your results and adjust as required.
He who dwells in the shelter of the Most High will rest in the shadow of the Almighty. I will say of the LORD, "He is my refuge and my fortress, my God, in whom I trust." Psalm 91:1-2