Calorie Calculators
Author: Tom Venuto
Date: Mar 01, 2000
Publisher: Fitness Renaissance
The first step in designing a personal nutrition
plan for yourself is to calculate how many calories
you burn in a day; your total daily energy expenditure
(TDEE). TDEE is the total number of calories that your
body expends in 24 hours, including all activities.
TDEE is also known as your "maintenance level".
Knowing your maintenance level will give you a
starting reference point from which to begin your
diet.
According to exercise physiologists William McArdle
and Frank Katch, the average maintenance level for
women in the United States is 2000-2100 calories per
day and the average for men is 2700-2900 per day.
These are only averages; caloric expenditure can vary
widely and is much higher for athletes or extremely
active individuals. Some triathletes and
ultra-endurance athletes may require as many as 6000
calories per day or more just to maintain their
weight! Calorie requirements may also vary among
otherwise identical individuals due to differences in
inherited metabolic rates.
Methods of determining caloric needs
There are many different formulas you can use to
determine your caloric maintenance level by taking
into account the factors of age, sex, height, weight,
lean body mass, and activity level. Any formula that
takes into account your lean body mass (LBM) will give
you the most accurate determination of your energy
expenditure, but even without LBM you can still get a
reasonably close estimate.
The "quick" method (based on total bodyweight)
A fast and easy method to determine calorie needs
is to use total current body weight times a
multiplier.
Fat loss = 12 - 13 calories per lb. of bodyweight
Maintenance (TDEE) = 15 - 16 calories per lb. of
bodyweight
Weight gain: = 18 - 19 calories per lb. of
bodyweight
This is a very easy way to estimate caloric needs,
but there are obvious drawbacks to this method because
it doesn't take into account activity levels or body
composition. Extremely active individuals may require
far more calories than this formula indicates. In
addition, the more lean body mass one has, the higher
the TDEE will be. Because body fatness is not
accounted for, this formula may greatly overestimate
the caloric needs if someone is extremely overfat. For
example, a lightly active 50 year old woman who weighs
235 lbs. and has 34% body fat will not lose weight on
3000 calories per day (255 X 13 as per the "quick"
formula for fat loss).
Equations based on BMR.
A much more accurate method for calculating TDEE is
to determine basal metabolic rate (BMR) using multiple
factors, including height, weight, age and sex, then
multiply the BMR by an activity factor to determine
TDEE. BMR is the total number of calories your body
requires for normal bodily functions (excluding
activity factors). This includes keeping your heart
beating, inhaling and exhaling air, digesting food,
making new blood cells, maintaining your body
temperature and every other metabolic process in your
body. In other words, your BMR is all the energy used
for the basic processes of life itself. BMR usually
accounts for about two-thirds of total daily energy
expenditure. BMR may vary dramatically from person to
person depending on genetic factors.
If you know someone who claims they can eat
anything they want and never gain an ounce of fat,
they have inherited a naturally high BMR. BMR is at
it's lowest when you are sleeping undisturbed and you
are not digesting anything. It is very important to
note that the higher your lean body mass is, the
higher your BMR will be. This is very significant if
you want to lose body fat because it means that the
more muscle you have, the more calories you will burn.
Muscle is metabolically active tissue, and it requires
a great deal of energy just to sustain it. It is
obvious then that one way to increase your BMR is to
engage in weight training in order to increase and/or
maintain lean body mass. In this manner it could be
said that weight training helps you lose body fat,
albeit indirectly.
The Harris-Benedict formula (BMR based on total
body weight)
The Harris Benedict equation is a calorie formula
using the factors of height, weight, age, and sex to
determine basal metabolic rate (BMR). This makes it
more accurate than determining calorie needs based on
total bodyweight alone. The only variable it does not
take into consideration is lean body mass. Therefore,
this equation will be very accurate in all but the
extremely muscular (will underestimate caloric needs)
and the extremely overfat (will overestimate caloric
needs).
Men: BMR = 66 + (13.7 X wt in kg) + (5 X ht in cm)
- (6.8 X age in years)
Women: BMR = 655 + (9.6 X wt in kg) + (1.8 X ht in
cm) - (4.7 X age in years)
Note: 1 inch = 2.54 cm.
1 kilogram = 2.2 lbs.
Example:
You are female
You are 30 yrs old
You are 5' 6 " tall (167.6 cm)
You weigh 120 lbs. (54.5 kilos)
Your BMR = 655 + 523 + 302 - 141 = 1339
calories/day
Now that you know your BMR, you can calculate TDEE
by multiplying your BMR by your activity multiplier
from the chart below:
Activity Multiplier
Sedentary = BMR X 1.2 (little or no exercise, desk
job)
Lightly active = BMR X 1.375 (light exercise/sports
1-3 days/wk)
Mod. active = BMR X 1.55 (moderate exercise/sports
3-5 days/wk)
Very active = BMR X 1.725 (hard exercise/sports 6-7
days/wk)
Extr. active = BMR X 1.9 (hard daily
exercise/sports & physical job or 2X day training, i.e
marathon, contest etc.)
Example:
Your BMR is 1339 calories per day
Your activity level is moderately active (work out
3-4 times per week)
Your activity factor is 1.55
Your TDEE = 1.55 X 1339 = 2075 calories/day
Katch-McArdle formula (BMR based on lean body
weight)
If you have had your body composition tested and
you know your lean body mass, then you can get the
most accurate BMR estimate of all. This formula from
Katch & McArdle takes into account lean mass and
therefore is more accurate than a formula based on
total body weight. The Harris Benedict equation has
separate formulas for men and women because men
generally have a higher LBM and this is factored into
the men's formula. Since the Katch-McArdle formula
accounts for LBM, this single formula applies equally
to both men and women.
BMR (men and women) = 370 + (21.6 X lean mass in
kg)
Example:
You are female
You weigh 120 lbs. (54.5 kilos)
Your body fat percentage is 20% (24 lbs. fat, 96
lbs. lean)
Your lean mass is 96 lbs. (43.6 kilos)
Your BMR = 370 + (21.6 X 43.6) = 1312 calories
To determine TDEE from BMR, you simply multiply BMR
by the activity multiplier:
Example:
Your BMR is 1312
Your activity level is moderately active (work out
3-4 times per week)
Your activity factor is 1.55
Your TDEE = 1.55 X 1312 = 2033 calories
As you can see, the difference in the TDEE as
determined by both formulas is statistically
insignificant (2075 calories vs. 2033 calories)
because the person we used as an example is average in
body size and body composition. The primary benefit of
factoring lean body mass into the equation is
increased accuracy when your body composition leans to
either end of the spectrum (very muscular or very
obese).
Adjust your caloric intake according to your goal
Once you know your TDEE (maintenance level), the
next step is to adjust your calories according to your
primary goal. The mathematics of calorie balance are
simple: To keep your weight at its current level, you
should remain at your daily caloric maintenance level.
To lose weight, you need to create a calorie deficit
by reducing your calories slightly below your
maintenance level (or keeping your calories the same
and increasing your activity above your current
level). To gain weight you need to increase your
calories above your maintenance level. The only
difference between weight gain programs and weight
loss programs is the total number of calories
required.
Negative calorie balance is essential to lose body
fat.
Calories not only count, they are the bottom line
when it comes to fat loss. If you are eating more
calories than you expend, you simply will not lose
fat, no matter what type of foods or food combinations
you eat. Some foods do get stored as fat more easily
than others, but always bear in mind that too much of
anything, even "healthy food," will get stored as fat.
You cannot override the laws of thermodynamics and
energy balance. You must be in a calorie deficit to
burn fat. This will force your body to use stored body
fat to make up for the energy deficit. There are 3500
calories in a pound of stored body fat. If you create
a 3500-calorie deficit in a week through diet,
exercise or a combination of both, you will lose one
pound. If you create a 7000 calories deficit in a week
you will lose two pounds. The calorie deficit can be
created through diet, exercise or preferably, with a
combination of both. Because we already factored in
the exercise deficit by using an activity multiplier,
the deficit we are concerned with here is the dietary
deficit.
Calorie deficit thresholds: How low is too low?
It is well known that cutting calories too much
slows down the metabolic rate, decreases thyroid
output and causes loss of lean mass, so the question
is how much of a deficit do you need? There definitely
seems to be a specific cutoff or threshold where
further reductions in calories will have detrimental
effects. The most common guideline for calorie
deficits for fat loss is to reduce your calories by at
least 500, but not more than 1000 below your
maintenance level. For some, especially lighter
people, 1000 calories may be too much of a deficit.
The American College of Sports Medicine (ACSM)
recommends that calorie levels never drop below 1200
calories per day for women or 1800 per day for men.
Even these calorie levels are extremely low. A more
individualized way to determine the safe calorie
deficit would be to account for one's bodyweight or
TDEE. Reducing calories by 15-20% below TDEE is a good
place to start. A larger deficit may be necessary in
some cases, but the best approach would be to keep the
calorie deficit through diet small while increasing
activity level.
Example 1:
Your weight is 120 lbs.
Your TDEE is 2033 calories
Your calorie deficit to lose weight is 500 calories
Your optimal caloric intake for weight loss is 2033
- 500 = 1533 calories
Example 2: Your calorie deficit to lose weight is
20% of TDEE (.20% X 2033 = 406 calories)
Your optimal caloric intake for weight loss = 1627
calories
Positive calorie balance is essential to gain lean
bodyweight
If you want to gain lean bodyweight and become more
muscular, you must consume more calories than you burn
up in a day. Provided that you are participating in a
weight-training program of a sufficient intensity,
frequency and volume, the caloric surplus will be used
to create new muscle tissue. Once you've determined
your TDEE, the next step is to increase your calories
high enough above your TDEE that you can gain weight.
It is a basic law of energy balance that you must be
on a positive calorie balance diet to gain muscular
bodyweight. A general guideline for a starting point
for gaining weight is to add approximately 300-500
calories per day onto your TDEE. An alternate method
is to add an additional 15 - 20% onto your TDEE.
Example:
Your weight is 120 lbs.
Your TDEE is 2033 calories
Your additional calorie requirement for weight gain
is + 15 - 20% = 305 - 406 calories
Your optimal caloric intake for weight gain is 2033
+ 305 - 406 = 2338 - 2439 calories
Adjust your caloric intake gradually
It is not advisable to make any drastic changes to
your diet all at once. After calculating your own
total daily energy expenditure and adjusting it
according to your goal, if the amount is substantially
higher or lower than your current intake, then you may
need to adjust your calories gradually. For example,
if your determine that your optimal caloric intake is
1900 calories per day, but you have only been eating
900 calories per day, your metabolism may be sluggish.
An immediate jump to 1900 calories per day might
actually cause a fat gain because your body has
adapted to a lower caloric intake and the sudden jump
up would create a surplus. The best approach would be
to gradually increase your calories from 900 to 1900
over a period of a few weeks to allow your metabolism
to speed up and acclimatize.
Measure your results and adjust calories
accordingly
These calculations for finding your correct caloric
intake are quite simplistic and are just estimates to
give you a starting point. You will have to monitor
your progress closely to make sure that this is the
proper level for you. You will know if you’re at the
correct level of calories by keeping track of your
caloric intake, your bodyweight, and your body fat
percentage. You need to observe your bodyweight and
body fat percentage to see how you respond. If you
don't see the results you expect, then you can adjust
your caloric intake and exercise levels accordingly.
The bottom line is that it’s not effective to reduce
calories to very low levels in order to
lose belly fat. In
fact, the more calories you consume the better, as
long as a deficit is created through diet and
exercise. The best approach is to reduce calories only
slightly and raise your daily calorie expenditure by
increasing your frequency, duration and or intensity
of exercise.
References:
1. Katch, Frank, Katch, Victor, McArdle, William.
Exercise Physiology: Energy, Nutrition, and Human
Performance, 4th edition. Williams & Wilkins, 1996.
2. Whitney, Eleanor, Rolfes, Sharon. Understanding
Nutrition, 8th Edition, Wadsworth Publishing, 1999.
3. American College of Sports Medicine. Position
Statement on proper and improper weight loss programs.
Medicine and Science in Sports and Exercise 15: ix -
xiii, 1983.
4. McDonald, Lyle. The Ketogenic Diet. Morris
Publishing. 1998
This article was provided courtesy of Tom Venuto
and
Burn the Fat. Tom is a lifetime
natural bodybuilder, personal trainer, gym owner,
freelance writer, and author of Burn The Fat Feed
the Muscle: Fat Burning Secrets of the World's Best
Bodybuilders and Fitness Models.
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