Calories:
How Many Do We Need?
Many people,
particularly those who are trying to lose weight, view calories as enemy and tend to
forget that we all need them to survive. Calorie is merely a way of measuring the
potential heat in the food we eat. Specifically, it is the amount of energy expended in
raising the temperature of one gram of water one degree Celsius. The unit for a calorie is
more accurately expressed as kilocalorie or kcal. Different people need different amounts
of calories to function efficiently. We will teach you how to determine that number in
this article and doing it may help you stay within the amount that's right for you.
The three areas that determine your calorie needs are:
- Basal Metabolic Rate or BMR
- Energy we use in physical activity
- Thermic Effect of Food - the calories needed for
digestion and absorption
Basal Metabolic Rate (BMR)
This is the energy it
takes to keep your involuntary body processes going. About 60 percent of the calories you
consume are used for such things as breathing, maintaining body temperature, manufacturing
hormones and keeping your heart pumping. The more total body surface area you have, the higher
your BMR is. Examples:
Other factors that
affect BMR:
Exercise. Depending on the length and intensity
of your exercise, you can boost your BMR for several hours afterward, up to 20 times that
which it is at rest. However this is only part of the story. Research has shown that an
individual's metabolic rate remains significantly increased for many hours even after the
exercise has ceased
Diet. Severe dieting can reduce your BMR as your
body attempts to conserve calories. This is our body's natural response to survive and not
a good idea for a healthy lifestyle.
Body Composition. Muscle burns more calories than
fat. The greater your ratio of lean to fat, the more calories you will burn.
Age. For every decade beyond the growth years
(about age 20), your caloric needs drop about 2%.
Energy
we use in physical activity
About 30 % of your
calories would be used for any physical activity you do, from tying your shoelace to
running a marathon. Of course, the marathon will take significantly more than an
additional 30%. In addition, people who do the same activity at the same pace for the same
amount of time can use up vastly different numbers of calories, depending on their size.
For example, if a family of three jogs side-by-side for 30 minutes, the 80kg father will
burn about 400 kcal, the 60kg mother will burn about 300 kcal and the 30kg child will burn
only about 180 kcal.
Thermic Effect of Food
That's
right, we are burning calories even while we are eating. Thermic effect of food can be
described as metabolic cost of ingesting, digesting and storing of food. This constitutes
about 10% of the total daily energy expenditure.
To
estimate how many calories you need daily, follow these steps:
Calculate your BMR energy needs:
Minus the age factor from the above:
2% for age 30-40
4% for age 40-50
6% for age 50-60
8% for age 60 and
above
Add the following
activity level factors to step 1's result
20% for sedentary
(mainly sitting all day)
30% for light activity
(such as walking to and from the bus stop, cooking dinner, etc.)
40% for moderate
activity (very little sitting, heavy housework and gardening)
50% for very active
(construction work, and active and prolonged physical sports)
Add that by another
10% (thermic effects of foods) to step 2's result to get your total daily energy needs.
Weight
management is about the manipulating of calories. One pound of fat is about 500 calories.
To lose weight,
you
need to consume 3,500 calories less for each pound (0.45 kg) you want to lose, or
increase
physical activity while maintaining your current level of eating, or
a
little of both - this is a preferred and more effective method than the two methods above
To gain weight, simply do the same in reverse.
