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Math Lesson: Counting Calories August 3, 2009

Filed under: food,hEaLtH — dragonfly180 @ 9:02 pm
Tags: , , , ,

I’ve stressed the importance of knowing how many calories to take in each day in a previous blog. You may be asking why and how do you figure this out? Let me answer both of those questions.
Why?
You can do all the walking and crunches and swimming you want, but if you’re eating too many calories, you just will not lose weight. For the first entire year I ran, I had this problem. I was running so much each week, but the scale barely moved. I just could not figure it out. I finally read about calories and understood why. I was taking in too many calories daily. My running was burning enough calories that I wasn’t gaining any weight, but I couldn’t lose because I had not created a deficit.

How?
Let’s go back to the Basal Metabolic Rate. This is the minimum that you body needs to survive and run bodily processes throughout the day while maintaining your weight as it is. To find out your BMR, use a BMR calculator: http://www.bmi-calculator.net/bmr-calculator/
Or you can use the BMR formula if you just like to do equations!
English BMR 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 )

Now, we have to do a little more math. My BMR is 1402.4 according to the BMR calculator.

Harris Benedict Formula

To determine your total daily calorie needs, multiply your BMR by the appropriate activity factor, as follows:

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 moderately 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

Using the Harris Benedict Formula above, I am probably “very active” according to these guidelines, so I need to multiply my BMR (1402.4) by 1.725, which equals 2419. This is the amount of calories I need to sustain the amount of activity I’m doing if I want to maintain my weight. But I have to create a deficit if I want to lose weight.

There are 3500 calories in a lb of fat. So to lose 1 lb per week, I have to get rid of 3500 calories for the week through food, exercise, or preferably both. I need 2419 per day for maintenance at my activity level, which comes to 16,933 for the week (2419 x 7). Now, 16933-3500=13433. If you divide that over the seven days of the week, that’s 1919 per day. So I need to consume around 1900 calories per day to lose 1 lb. If I want to lose 2 lbs, I create a deficit of 7000 calories (or 3500 x 2). 16933-7000=9333/7=1419. Therefore, if I hope to lose 1 to 2 lbs, I need to consume between 1419 and 1919 per day. If I stop working out and become sedentary, I’d need far fewer calories per day in order to lose weight. So the more you workout, the more you are able to eat! :o) Never go below 1200 calories per day, though, even if the math comes out to less. This can be detrimental to your health and can also make you stop losing weight, because your body will go into starvation mode and your metabolism will slow down. You can make up for the extra calories by exercising.
For instance, suppose you are a sedentary person with a BMR of 1402.
1402.4 x 1.2 (for sedentary in the Harris Benedict formula above)= 1683 (your maintenance calories)
1683 x 7= 11781 (weekly calories for maintenance)
11781-3500= 8281/7= 1183(amount of calories needed per day to lose 1 lb. for the week)

Since this number is low and can possibly hurt your health, you could supplement it with exercise. For instance, walking for 30 minutes at my weight burns 156 calories. If I did that for four days each week, that would create a deficit of 624 calories that I could add back into my calories for the week, therefore enabling me to eat more calories per day while still losing the 1 lb. This is how the math would look:
11781 (weekly calories for maintenance) + 624 (your bonus calories from your exercise calorie deficit) = 12405 calories
12405-3500=8905/7=1272 calories per day (to lose 1 lb)
So by walking, you’ve gained yourself a few more calories per day to consume while still being able to lose the 1 lb. Imagine if you walked for an hour 5 days a week! But that’s enough math for me today.  ;o) If you want to see how many calories certain activities burn, check out this website:
http://www.healthstatus.com/calculate/cbc

One to two lbs per week is the suggested rate for losing weight. If you try to create a deficit for more than that, research shows that your chances of keeping it off in the long run are slim. Slow but steady weight loss should be your goal. That will also give you time to adapt to your new lifestyle.

Hope all that math wasn’t too discouraging. I just wanted to provide good examples. If you can figure out your calorie range and then start sticking to it, losing weight is pretty easy. Here are a few websites that will make it very easy to find calories for the foods that may not have labels you can peruse, such as fresh produce or a meal at a restaurant:

http://www.calorieking.com/
http://www.nutritiondata.com/
http://www.thedailyplate.com/

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One Response to “Math Lesson: Counting Calories”

  1. Jordan Says:

    This is so good to know. Now, I completely understand why I haven’t been able to loose weight. It takes waaay less calories to maintain my weight than what online calculators estimated for me. (D’oh!). Also, I didn’t know that 3,500 = 1lb of fat. That’s also good to know. Thanks for all this info! :)


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