What is BMR?
When following any fat-burning diet, it’s really critical that you’re familiar with your BMR. BMR stands for Basal Metabolic Rate. Basal metabolic rate is the amount of energy or calories you consume at rest. Another more common title for basal metabolic rate is metabolism. Your metabolism incorporates functions of your body such as respiration, digestion of food, and circulation. Each person’s metabolism is unique to their own physical makeup and their own physical practice.
Research conducted in 1992 and 1997 indicated that your aerobic fitness level has no interconnection with your BMR level. Anaerobic exercise, like lifting weights, causes your body to build more muscle mass that doesn’t contain fat and uses more energy. You can build your metabolism through weight training and building additional lean body mass.
Why is it essential to know your BMR?
By knowing your BMR, you know how many calories your body burns while at rest. While following any fat-burning diet, you should never reduce your daily calorie intake too far below what your body needs to go on, otherwise the starvation reaction will kick in and you will no longer be burning fat, but muscle. Knowing your BMR allows you to modify your daily calorie intake so that you have a fat loss default and will burn fat, but it allows you to avoid going too low and you will end up starting the starvation reaction in your body. If you have achieved your weight loss goals, knowing your BMR allows you to design a nutritional plan according to the number of calories your body needs to stay alive and thus be able to take care of your current weight.
The volume of calories your body burns each day is called TDEE (Total Daily Energy Expenditure). Your TDEE is your BMR then multiplied by an activity factor that adds an allowance for the amount of physical activity you get. TDEE is also known as your “maintenance level.” Being familiar with your maintenance level will give you an opening reference point from which to launch your fat-burning diet. Calorie intake can vary widely and is much higher for athletes or highly active people
How is your BMR calculated?
There are some formulas that can be used to calculate BMR.
I will detail 2 formulas here:
The Harris-Benedict formula (based on total body weight)
This formula uses height, weight, age, and gender to calculate your Basal Metabolic Rate (BMR). The only thing this formula doesn’t take into account is lean body mass so it may be inaccurate in the very muscular or very fat.
Men: BMR = 66 + (13.7 X weight in kg) + (5 X height in cm) – (6.8 X age in years)
Women: BMR = 655 + (9.6 X weight in kg) + (1.8 X height in cm) – (4.7 X age in years)
Example
I am a 33 year old female who weighs 57 kg and is 168 cm tall.
BMR = 655 + (9.6 x 57) + (1.8 x 168) – (4.7 x 33) = 655 + 547.2 + 302.4 – 155.1 = 1,349 calories per day
To find your TDEE, multiply your BMR by an activity factor that works for you from the table below:
Sedentary = BMR X 1.2 (little or no exercise, desk job)
Mildly active = BMR X 1.375 (light exercise/sports 1-3 days/week)
Moderately active = BMR X 1.55 (moderate exercise/sports 3-5 days/week)
Very Active = BMR X 1.725 (intense exercise/sports 6-7 days/week)
Extra Active = BMR X 1.9 (intense daily exercise/sports and physical work or 2X day training ie marathon, contest, etc.)
So if I am slightly active from the above, my TDEE would be 1349 x 1375 = 1854 calories per day.
Katch-McArdle Formula (BMR based on lean body weight)
If you know your body fat percentage, and therefore your lean body mass, you can use the more defined BMR formula. This formula takes lean mass into account and is therefore more conclusive. 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 represents LBM, this unique formula applies to both men and women.
BMR = 370 + (21.6 X lean mass in kg)
Example:
weights 57 kg
Your body fat percentage is 27%
Your lean mass is 41.61 kg.
Your BMR = 370 + (21.6 X 41.61) = 1268 calories
To determine TDEE of BMR, simply multiply BMR by the activity multiplier:
Example:
Your BMR is 1268 calories
Your activity level is moderately active (exercise 3-4 times a week)
Your activity factor is 1.55
Your TDEE = 1.55 X 1268 = 1965 calories