## Wednesday, February 20, 2013

### The Skinny on Calories

Hey Kids! Rachel here and today, I want to talk to you about the real deal with calories.  We all know that weight loss or weight gain comes down to how many calories we eat and how many calories we burn.  You must burn more than you eat to lose weight, right?  But how many calories do you need to burn to lose weight? How many calories can you eat?

First thing is first: we need to come up with your basal metabolic rate.  What does this mean? Basically, your BMR is how many calories your body would burn if you were to do nothing but lie in bed all day.  Your body needs calories for your heart to pump and your blood to circulate, for your lungs to fill and empty, your GI tract to digest, your lymph to flow, your brain to work... twenty-four hours a day.  It is important that we never eat below our BMR also, or certain hormones can kick into play that can actually stall fat loss.

So, how do you calculate your BMR? Outside of a clinical laboratory, the easiest and most accurate way to do it yourself is to use something called the Harris Benedict formula.

The Harris Benedict Formula:
Women: BMR = 655 + ( 4.35 x weight in pounds ) + ( 4.7 x height in inches ) - ( 4.7 x age in years )
Men: BMR = 66 + ( 6.23 x weight in pounds ) + ( 12.7 x height in inches ) - ( 6.8 x age in year )

Or, you can plug your digits into this calculator on this website here: bmi-calculator.net/bmr-calculator/

Now that we know what our BMR is, we need to take activity level into account.  Whether we're sitting on the couch all day and taking sporadic bathroom breaks or on our feet all day long, we must take our activities into account.

1. If you are sedentary (little or no exercise) : Calorie-Calculation = BMR x 1.2
2. If you are lightly active (light exercise/sports 1-3 days/week) : Calorie-Calculation = BMR x 1.375
3. If you are moderatetely active (moderate exercise/sports 3-5 days/week) : Calorie-Calculation = BMR x 1.55
4. If you are very active (hard exercise/sports 6-7 days a week) : Calorie-Calculation = BMR x 1.725
5. If you are extra active (very hard exercise/sports & physical job or 2x training) : Calorie-Calculation = BMR x 1.9

There.  Now we have the number of calories that you would need to eat to maintain your weight.  But, we what if we want to lose weight?

Well, first let's remember that 1 lb, whether fat or muscle, is equal to 3,500 calories.  That means, to lose 1 lb a week, we would need to subtract 3,500 calories from your total calories that you consume for the week.  The easiest way to do this is to divide 7 (7 days of the week) into 3,500 and we get 500.  So we take your calorie total and subtract 500 to lose 1 lb a week.

Now why can't we lose more than that?  You can but we want the rest of the weight loss to be burned not starved.  That means, you need to bring it in your workouts to burn the second lb.

Here's the thing: your body does not want to let go of more than 1-2 lb of fat a week at the most.  The reason for this is your hormones.  We have hormones that tell us we're tired, that tell us we're happy, that tell our bodies to store food as fat, that tell our bodies that we're safe and that we're stressed.  When we have too much of a calorie deficit, those stress hormones fire (ever hear of cortisol?) and our brain decides that we're starving and our lives are in danger - we must hold on to our fat for survival.  Fat will keep you alive, but you don't need muscle if you're starving so your body would rather break down protein from your muscles back into amino acids to keep you alive than burn fat.  It is only when we are providing our bodies with enough fuel that our bodies decide that they can burn fat safely.

To make sure you are eating within your ideal calorie range, it is important to log the calories you eat. It is too easy to lose track of what you eat if you aren't logging each meal.  Using a program like Livestrong.com/Myplate which also has a cell phone app for ease of use, can make doing this a lot easier.  This is a habit that is important to form and once you get into that habit of logging your calories, you won't even think about it anymore.  It takes about 3 weeks to make something into a habit and if you stick with a healthy diet and workout routine for 3 weeks consistently, you'll be well on your way to changing your body!