This information was taken directly from an online article by Regina Schumann. The full article, well worth
the read, can be found here. Please take the time to read the entire article as it is quite informative.
I use this portion merely to define BMR...
----------------------------------------------------------------------------------------------------------------------
The human body works with energy to function.
This energy comes from foods eaten and the calories it provides. The very minimum the body needs are calories required for
the energy needed to meet the needs for basic function - blood flow, respiration, heartbeat, brain function, regulation of
body temperature, nerve impulses, etc. - called the "Basal Metabolism". The energy required by the body averages 70% of calories
required each day!
When calorie intake is restricted to levels below the Basal Metabolism, the body restricts its requirement
for calories by conserving energy expenditure - it slows the body's base requirement to survive in order to conserve it's
energy stores for an emergency (fight or flight responses). This is often referred to as "starvation mode" because the body
is convinced it is starving and enters into a metabolic state that will conserve energy to allow survival for extended periods
without sufficient calorie intake.
Entering into "starvation mode" does not happen overnight, but takes an extended
period of time - typically one week to one month, depending on how severely restricted calories are. The more calories are
restricted, the faster the body will seek survival and enter into metabolic conservation of energy.
On calorie restricted
diets, this is often the state one finds himself in after a couple of weeks or months following a low-calorie diet. Weight-loss
slows to a crawl or stalls completely and hunger pangs are more frequent as the body screams for the calories it needs. The
same effect can be seen with those following a carbohydrate-restricting plan when they do not eat enough calories each day.
A
person's Basal Metabolism is completely individual. It is based on a number of factors that include age, gender, height, and
weight. A 35 year-old female, standing 5'5" tall and weighing 200 pounds will have a higher Basal Metabolism than a 35 year-old
female standing 5'5" tall and weighing only 150 pounds. While they both are the same height, gender and age, their weight
differences create a disparity in their basal metabolic needs, with the person who is heavier requiring more calories each
day to support basic function. It is for this reason there is no standard guideline to use for everyone - Basal Metabolism
must be calculated for the individual, not an age group, gender group or height group alone.
----------------------------------------------------------------------------------------------------------------------
