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How to calculate your BMR for weight loss

Posted Jan 07 2009 2:47pm

scale Your Basal Metabolic Rate (BMR) is how many calories your body requires just to function without losing weight. The idea behind figuring out your own BMR is so that you can calculate the amount of calories you need to burn in order to actually lose weight.

This is the formula for women:

BMR = 655 + (9.6 X wt in kg) + (1.8 X ht in cm) - (4.7 X age in years)
Note: 1 inch = 2.54 cm and 1 kilogram = 2.2 lbs)

So for me, as of today (250lbs. and 67.5 in. at 31 years of age) I’ll calculate my BMR as so:

655 + (1090.94) + (308.61) - (145.7) = 1908.85 (1909)

So in order to figure out how many calories your body requires at rest, versus how many it needs to get in accordance with exercise to lose weight, you have to do a little more math.

So my BMR is 1909. By looking at the Activity Levels Multiplier below, given that I currently have a sedentary lifestyle (desk job - I’m glued here most days), I’ll take that number and multiply it by 1.2 and get 2290.8 (2291). THAT is the number of calories I’d have to consume in order to just maintain my weight, without adding any additional exercise.

Let’s take a look at the Activity Levels Multiplier…

Sedentary = BMR X 1.2 (no exercise, desk job, inactive lifestyle)
Light = BMR X 1.375 (light exercise (slow walks, very light exertion) 1-3 days/wk)
Moderate = BMR X 1.55 (moderate exercise (a little sweating, light to medium exertion) 3-5 days/wk)
High = BMR X 1.725 (hard exercise (heavy sweating, long duration, heavy exertion) 6-7 days/wk)
Extreme = BMR X 1.9 (hard daily exercise AND physically demanding  job or twice daily training, i.e marathon, contest, am/pm workouts, etc.)

Let’s say that a month from now, I’m doing light, 20 minute walks, three times per week. In order for my body to MAINTAIN the current weight of 250, I’d have to consume 2625 calories per day. That’s about 130 more than if I were at sedentary activity levels.

Now, in order to lose weight, you must create a deficit either by reducing the amount of calories you consume (in relation to the number you get with your BMR and activity level multiplier for maintenance) and/or you have to burn more calories, by increasing your activity level.

Creating a deficit of 500 calories per day will equal a total deficit of 3500 calories per week, and oh how convenient! 3500 calories is equal to ONE POUND.

Okay, another scenario…

At my current weight, I decide that I’m going to do moderate activity. I’m going to sweat it out cardio style 4 days a week to the point where I’m sure I’m getting a moderate workout.

My BMR x 1.55 = 2959

Now this means that if I were working out but didn’t want to lose weight, I’d have to consume almost 3,000 calories a day! If I were to knock that down to just 1939 calories per day, I’d create a deficit of 7,000 calories per week, and would lose TWO pounds per week!

There are lots of ways to create deficits. You can cut your intake by 500 and ramp up the workouts to burn 500. (Or 250 and 250 if you want to go slower, and there’s nothing wrong with that.)

I don’t think it’s all that hard to consume 1939 calories per day, and work out moderately 4-5 days per week, do you? I can do this!!

So what do you think? Calculate your BMR with the formula above, multiply it based on your activity level, and see if you can come up with a way to either ramp up the workouts or consume less calories, so you too can lose weight!

(I’d recommend re-evaluating your BMR and activity levels once a month to maintain a steady weight loss, or get yourself to “maintenance” mode if you’re done losing and want to maintain your current weight.)

(Image: Tanita UM060 Scale with Body Fat Monitor, Body Water Percentage & Health Range Indicator )

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