Daily Calorie Requirement

To calculate the number of calories you need to consume each day, you need to calculate your normal energy needs (which depends on your age and weight), adjust for your metabolic rate (which depends on how active you are) and add the calories you burn exercising (which depends on what exercise you do).[i]

This is easier than it sounds at first, and the calculation is set out below.  But simplest of all, you can feed your personal information into this calculator.

The first step is to estimate your resting calorie requirement.  Simply enter your weight (in kilograms) into one of the formulas in Table 6.6 below.

Table 6.6 Resting metabolic requirement[ii]

Age Men Women
10 – 18 years 17.5 x W + 651 12.2 x W + 746
19 – 30 years 15.3 x W + 679 14.7 x W + 496
31 – 60 years 11.6 x W + 879 8.7 x W + 829

Example: Fred weighs 74kg, and he is a 35 year old male, so Fred’s resting metabolic requirement is:
(15.3 x 74) + 679 = 1811 calories per day.

The second step is to multiply this by your activity level:

Table 6.7 Activity level and metabolic rates

Activity level Multiplier
Sedentary 1.4
Moderately active
(e.g. regularly walking during the day)
1.7
Very active 2.0

Example: Fred is moderately active: he has a sedentary job as a civil servant, but he exercises every day, including cycling to work and running.  So Fred multiplies by 1.7:
1.7 x 1811 = 3078 calories per day.

Finally, the third step is add the number of calories you expend on average each day exercising.  If you run, you can estimate this as 100 calories for every mile you run.  Table 6.8 below shows approximate figures for other activities.

Example: Because Fred runs about 40-45 miles a week, which is an average of about 6 miles a day, Fred adds 600 calories:
3078 + 600 = 3678 calories a day.

This means that Fred’s equilibrium energy intake should be around 3678 calories a day.  (This means that Fred can eat pretty much anything he wants!)

In reality, there is considerable variation from person to person.  Some people are born with a higher metabolic rate than others.  If you have a large amount of lean muscle tissue you will tend to burn more energy than someone who does not.  So you cannot use this calculation as a hard-and-fast rule.  Instead, use it as a rule of thumb to get an idea of the sort of calorie intake you are likely to need, and then see what works for you in practice.

Table 6.8 Calories expended in typical exercises [iii]

Activity Kcal / hour
Aerobics (high intensity) 520
Aerobics (low intensity) 400
Cycling (16km / hour) 385
Cycling (9 km / hour) 250
Running (6 min / mile) 1000
Running (10 min / mile) 600
Squash 615
Swimming (vigorous) 630
Weight training 270 – 450
Note: This table assumes a person weighing 65kg.
Calorie consumption would be higher for heavier people.

[i] This section owes much to Anita Bean The Complete Guide to Sports Nutrition, 2000. (A&C Black).

[ii] Williams, M.H. Nutrition for Health, Fitness and Sport (1999). McGraw-Hill.

[iii] Anita Bean The Complete Guide to Sports Nutrition, 2000; page 113.

One Response to Daily Calorie Requirement

  • Rokas:

    why Fred uses formula of a 25 yo?

    Example: Fred weighs 74kg, and he is a 35 year old male, so Fred’s resting metabolic requirement is:
    (15.3 x 74) + 679 = 1811 calories per day.

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