Basal Metabolic Rate (BMR)

When we go travelling we automatically do something very naturally. To access where we want to go we always start from where we are and then think about our best ways to get to our destinations and how much effort and time it requires. This applies to weight loss efforts as well but seldom most of us follow. For us to lose weight we need to know and understand situation of our body, what is its current energy requirement and then we can choose the correct attainable destination (read ideal weight) and also the best way to get there. The starting point in understanding situation of our body is to know your Basal Metabolic Rate (BMR).

What is Basal Metabolic Rate (BMR)?

Basal Metabolic Rate (BMR) is the minimum amount of energy you need for normal functioning of your body, if you did nothing all day. Basal Metabolic Rate is usually measured and expressed in KCal popularly known as Calories. This is the energy needed for functioning of vital organs like heart, lungs, kidneys, nervous systems and other key organs and does not consider any energy requirement in addition to it. All extra activities you do will require additional energy which is on top of this metabolic basal rate commonly known as Active Metabolic Rate (AMR). BMI is closely related to Resting Metabolic Rate (RMR) which is the minimum energy needed for the body in resting condition (Metabolic Basal Rate is calculated under more stringent, restrictive conditions). Though Metabolic Basal Rate is more popular Resting Metabolic Rate is more relevant for our need.

Though both BMR and RMR can only be calculated with lot of equipments under lab conditions, they can also be approximately arrived using some of the key aspects of our body. Our total daily energy need is further calculated by considering energy needed for all other activities (AMR) we will be doing on a 24 hour day period and adding BMR/RMR value to it.

What does Metabolic Basal Rate depend on?

Metabolic Basal Rate contributes 70-75% of total calories used by the body. However this number is dependent on various other factors. Hence this is the major factor which will help determine the amount of calories needed for you to maintain, loose or gain weight. The key parameters which influence are as below.

  • Gender – Men due to their physique tend to require more energy. This is due to higher percentage of muscle in men as compared to women.
  • Age – BMR reduces (in very small percetages) as the age increases.
  • Weight – BMR is proportional to weight of the person. This extra need for energy is due to that added effort for each organ to do the same task.
  • Body – The person's physique is also a contributor for BMR. The bigger the body more energy is needed for an organ to do the same task.
  • Body Fat – The fat content of the body negetively influence BMR. This means that more the fat lesser the BMR. This is because the muscles tend to consume more calories than fat and hence hight the fat (i.e lower the muscle) lesser the BMR.
  • Others – Temperatures (both internal and external), Thyroxin produced by thyroid glands, genetics of the person influence BMR, at times greatly.

 

How to calculate Metabolic Basal Rate?

For the purpose of weight loss we need to get an idea of our BMR and there are few methods using which you can calculate it. Some methods are simple and easy but gives only an approximate idea where as others are more detailed and more accurate but require more inputs. For accurate calculations Lean Body Mass (LBM) of your body has to be taken into consideration as it gives very accurate picture of calories needed. So all the methods mentioned below which don't consider LBM into account will only give an approximate value but it is good enough for most people (except if you are an athlete). The below section gives some selected web resources where you can calculate your own BMR.

In the simplest (and the crudest) method of all, BMR is calculated as a direct multiplication of person's weight (pounds) with approximate energy needed for each pound of weight. Typically we need 10-15 calories per pound of our weight. So BMR of a person weighing 150 pounds will be 1500 Calories (150 * 10). Main drawback of this method is that it doesn’t take into account of activity levels of the person and hence might miscalculate the BMR value (which could be way off target for very active people or athletes). However there are few simple methods which do take into account of activity levels. Below is a list of simple BMR calculators (in the order of their complexities, first being the simplest).

  • Discovery.com – Very simple and easy BMR calculator which takes into account of your age, height, weight and gender.
  • About.com – This calculator takes into account of person's lifestyle (i.e. activity levels) along with above basic factors.
  • PreventDisease.com – This calculator not only calculates the BMR but also gives you option to enter amount of time you spend on each different activity we typical do on daily basis. This give you a better idea of how much total calories you need on daily basis.

(The last link appears to be most accurate as it considers all different activities of your day)

 

More about Metabolic Basal Rate Calculations

The above consolidated material is good enough for any average person who wants to know about Metabolic Basal Rate before kick starting his/her weight loss/gain program. However if you are still keen to know more about what is the science behind the calculations and other in-depth knowledge please visit be ShapeFit.com.

Closing Note

Metabolic Basal Rate is the correct starting point for your weight loss (or gain) journey. It is easy to get tempted by crowd pulling headline articles like "Loose 10 pounds in 10 days" or "Loose 5 Pounds now" and start following them without checking if such a bold claim can be applicable to your case or not. In most cases it leads to disappointment as all these claims are generic claims and don’t apply to everyone. If you have still not calculated your BMR then go ahead and calculate using the above links. Once that is done the next step is to find out your Body Mass Index (BMI) to know in if you are overweight (if yes, what is the danger level) or not and so on. Once you know these two numbers you can sit and choose your weight loss targets and time periods to achieve them.

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