First, you need to know what BMR stands for!  BMR stands for Basal Metabolic Rate.  This is the amount of energy (calories) that your body needs to function on a daily basis.  In other words, this is the number of calories you can consume and maintain your current weight.  

It might seem obvious why this is important since it gives you the number of calories you can consume and not gain weight.  While it may seem logical to just consume fewer calories in order to lose weight, the important part is to know by HOW many calories you should reduce your daily intake.

Enter in the Harris-Benedict Principle.  This formula is a fairly simple calculation that helps you determine your ‘maintenance calories’.

Step 1

Women:
655 + (4.3 x weight in pounds) + (4.7 x height in inches) – (4.7 x age in years)

Men:
66 + (6.3 x weight in pounds) + (12.9 x height in inches) – (6.8 x age in years)

*NOTE: These formulas are only for adults

Step 2

Incorporate your level of activity by using these multipliers:

• If you are sedentary (little to no exercise) : BMR x 20 percent (multiply by 1.2)
• If you are lightly active: BMR x 30 percent (multiply by 1.3)
• If you are moderately active (You exercise most days a week.): BMR x 40 percent (multiply by 1.4)
• If you are very active (You exercise intensely on a daily basis or for prolonged periods.): BMR x 50 percent (multiply by 1.5)
• If you are extra active (You do hard labor or are in athletic training.): BMR x 60 percent (multiply by 1.6)

As an example, I will use my starting weight from 3 years ago (approx. 300 pounds):

66 + (6.3 x 300 lbs) + (12.9 x 71.5 inches) – (6.8 x 36 yo) = 2633 kcal (calories)
Sedentary Multiplier:  2633 kcal * 1.2 = 3159 kcal maintenance

That’s a lot of calories!  Now that I have my BMR, I need to determine my target calories for fat loss.  Please notice that I said ‘fat loss’.  When you hear people talking about going on a ‘diet’ they commonly refer to it as losing ‘weight’.  You don’t want to just lose weight.  You want to minimize muscle loss/deterioration.  Losing muscle will actually cause your metabolism to slow which will cause your BMR to drop.  If your BMR drops, fat loss will slow and you won’t see the results you are expecting.  See how that works?

In the scenario above, what should my target calories be? If I had someone with the above BMR come to me and ask my opinion, I would recommend a 500 calorie deficit and become at least moderately active.  A 500 calorie deficit alone would be about a pound per week.  If you couple that with burning 500 calories (2100 calories plan) while exercising most days of the week, you are actually decreasing your calories by 1000.  A 1000 calorie deficit should yield a 3 1/2 pound decrease each week.  If you lose much faster than that, then you WILL begin to lose muscle and you WILL slow your metabolism. 

This would be a good starting point.  Obviously, everyone’s metabolism is different and, in the above circumstance, it may not yield the desired results.  If so, then adjust as needed until you find the ’sweet spot’.  I shouldn’t have to tell you that you need to be honest with your weight when you do this.  Any number fudging can have negative consequences.

While it is great to decrease your caloric intake, it is equally important to eat the right foods.  In upcoming blogs, I will  cover exactly what that means.  For now, I would recommend getting aquainted with any of the free calorie counters out there.  Here are some:

• http://www.fitday.com
• http://www.dailyburn.com
• http://www.calorieking.com