HOW MANY CALORIES SHOULD YOU CONSUME?
The
number of calories you need to eat each day depends on several factors,
including your age, size, height, sex, lifestyle, and overall general health. A
physically active 6ft 2in male, aged 22 years, requires considerably more
calories than a 5ft 2ins sedentary woman in her 70s.
It has been discovered that
even factors such as how you eat your food can influence how many calories get
into your system. The longer you chew your food,
the more calories the body retains, a team from Purdue
University found.
If you would like to learn more
about calories - what they are and what they are important for - you might want
to take a look at our Knowledge Center article all about calories.
The rest of this article will discuss how your body uses calories and how many
your body might need to achieve optimum energy levels.
How many calories do I need to eat per day?
The Harris-Benedict
equation, also known as the Harris-Benedict principle, is used to estimate what
a person's BMR (basal metabolic rate) and daily requirements are. The person's
BMR total is multiplied by another number which represents their level of
physical activity. The resulting number is that person's recommended daily
calorie intake in order to keep theirbody weight where it is.
This equation has limitations. It does not
take into account varying levels of muscle mass to fat mass ratios - a very
muscular person needs more calories, even when resting.
How
to calculate your BMR
§ Male adults
66.5 + (13.75 x kg body weight) + (5.003 x height in cm) - (6.755 x age) = BMR
66 + ( 6.23 x pounds body weight) + ( 12.7 x height in inches ) - ( 6.76 x age) = BMR
66.5 + (13.75 x kg body weight) + (5.003 x height in cm) - (6.755 x age) = BMR
66 + ( 6.23 x pounds body weight) + ( 12.7 x height in inches ) - ( 6.76 x age) = BMR
§ Female adults
55.1 + (9.563 x kg body weight) + (1.850 x height in cm) - (4.676 x age) = BMR
655 + (4.35 x kg body weight) + (4.7 x height in inches) - (4.7 x age) = BMR
55.1 + (9.563 x kg body weight) + (1.850 x height in cm) - (4.676 x age) = BMR
655 + (4.35 x kg body weight) + (4.7 x height in inches) - (4.7 x age) = BMR
BMR calculators
You can use our BMR calculators below to work
out your BMR. One uses metric measurements and the other uses imperial
measurements - the choice is yours.
1) Metric BMR Calculator
Please note that both of these calculators
require JavaScript to be enabled in your browser settings. Results will appear
in the box underneath these calculators.
Gender:
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Age:
(years) |
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Height:
(in cm, e.g: 183) |
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Weight:
(in kg, e.g: 63) |
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BMR Calculator Result
Your BMR value is 1822. This means that your body will burn 1822
calories each day if you engage in no activity for the entire day.
Working out your daily
calorie requirement
To work out a figure for your calorie
requirement per day, we apply levels of physical activity to the equation as
per the guide below:
§ Sedentary lifestyle - if you do very little or
no exercise at all
Your daily calorie requirement is BMR x 1.2
Your daily calorie requirement is BMR x 1.2
§ Slightly active lifestyle - light exercise
between once and three times per week
Your daily calorie requirement is BMR x 1.375
Your daily calorie requirement is BMR x 1.375
§ Moderately active lifestyle - if you do
moderate exercise three to five days per week
Your daily calorie requirement is BMR x 1.55
Your daily calorie requirement is BMR x 1.55
§ Active lifestyle - if you do intensive/heavy
exercise six to seven times per week
Your daily calorie requirement is BMR x 1.725
Your daily calorie requirement is BMR x 1.725
§ Very active lifestyle - if you do very
heavy/intensive exercise twice a day (extra heavy workouts
Your daily calorie requirement is BMR x 1.9
Your daily calorie requirement is BMR x 1.9
The human body and energy usage
For the human body to remain alive, it requires energy. Approximately 20% of the energy we use is for brain metabolism. The majority of the rest of the body's energy requirements are taken up for the basal metabolic requirements - the energy we need when in a resting state, for functions such as the circulation of the blood and breathing.
If our environment is cold, our metabolism increases to produce more heat to maintain a constant body temperature. When we are in a warm environment, we require less energy.
We also require mechanical energy for our skeletal muscles for posture and moving around.
Respiration, or specifically cellular respiration refers to the metabolic process by which an organism gets energy by reacting oxygen with glucose to produce carbon dioxide, water and ATP energy. How efficiently energy from respiration converts into physical (mechanical) power depends on the type of food eaten, as well as what type of physical energy is used - whether muscles are used aerobically or anaerobically.
Put simply - we need calories to stay alive, even if we are not moving, and need calories to keep our posture and to move about.
How much should I weigh?
As with how many
calories you should consume, your ideal body weight depends on several factors. These include your age, sex, bone
density, muscle-fat ratio, and height.
§ BMI (Body Mass Index) - some say BMI is a good way of working out what you should
weigh. However, BMI does not take into account muscle mass. A 100-metre Olympic
champion weighing 200 pounds (about 91 kilograms), who is 6 feet (about 1mt
83cm) tall, who has the same BMI as a couch potato of the same height, is not
overweight, while the couch potato is overweight.
§ Waist-hip ratio - this measurement is said to be more accurate
at determining what your ideal weight should be, compared to BMI. However,
waist-hip ratio does not properly measure an individual's total body fat
percentage (muscle-to-fat ratio), and is also limited.
Waist-to-height ratio - this
new way of determining ideal body weight is probably the most accurate one
available today. It was presented by Dr. Margaret Ashwell, ex-science director
of the British Nutrition Foundation, and team at the 19th Congress on Obesity in Lyon, France, on
12th May, 2012. It is also a very simple calculation; easy for lay people to
work out. Put simply, to achieve and/or maintain your ideal body weight,
"Keep your waist circumference to less than half your height."
If you are a 6ft (183cm) tall
adult male, your waist should not exceed 36 inches (91 cm).
If you are a 5ft 4 inches (163
cm) tall adult female, your waist should not exceed 32 inches (81 cm)
How do I measure my waist? - according to the World Health Organization (WHO), you should place the tape-measure half-way between the lower rib and the iliac crest (the the pelvic bone at the hip).
Fast facts on daily calorie intake
Here are some key
points about daily calorie intake. More detail and supporting information is in
the main article.
§ Recommended calorie intake depends on factors
such as age, size, height, sex, lifestyle and overall general health.
§ The longer you chew your food, the more
calories your body retains.
§ Recommended daily calorie intakes in the US are
2,700 for men and 2,200 for women.
§ Eating a big breakfast could help with weight
reduction and maintenance.
§ When food is eaten may matter as much as what
and how many calories are eaten.
§ Average calorie consumption in industrialized
nations and a growing number of emerging economies is higher than it used to
be.
§ Approximately 20% of the energy used in the
human body is for brain metabolism.
§ Ideal body weight depends on several factors including age, bone density and
muscle-fat ratio.
§ The types of food that calories are acquired
from are highly important in terms ofnutrition.
§ A 500-calorie meal consisting of fruits and
vegetables is much better for your health and will keep you from being hungry
for longer than a 500-calorie snack of popcorn.
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