A major part of the weight loss equation, Calories, requires some math.
Oh, stop whining. This is where all that Algebra you thought you'd never use will come in handy!
Basically, a pound of fat contains 3500 calories. For each pound of fat you want to lose, you must BURN 3500 calories, or create a 3500 calorie DEFICIT (deficit being the difference between what your body uses to function and how many calories you feed it in food and drink). If you want to lose a pound per week, that's 500 calories per day you must cut back. 2 pounds per week, 1000 calories per day you must cut back. See the picture?
More than 2 pounds per week isn't recommended because it's simply not sustainable. You get to the point where you're having to exercise 3, 4, 5 hours/day to get that kind of weight loss. That's why it'll work for the Biggest Loser, but not for you, unless you enroll yourself in a dramatic weight loss camp and live there fulltime and workout fulltime.
So, assuming you want to lose the max, 2 pounds per week, and you have to create a 1000 calorie per day deficit, how do you know how many calories you're consuming, how many calories you SHOULD be consuming, and how do you know how many calories you're burning?
If you're relying on that number readout on the elliptical and the treadmill, I have BAAAAAAD news for you. They are far too generic, they only give a ballpark, and they constantly overestimate calories anywhere from 10-30%! So what's a dieter to do?
I'll tell you what you're going to do. You're going to use the following formulas to DO THE MATH. You're going to find out how many calories you should be eating, to lose and to maintain your weight, and you're going to find out what your maximum heart rate is, and what your target heart rate is, and how many calories you burn during exercise, given your average heart rate throughout the workout. I apologize in advance for being pedantic, but in weight loss, precision is everything!
Are you ready? Sure you are. Here we go!
How Many Calories You Need
A lot of emphasis is placed on BMR (Basal Metabolic Rate). This is the number of calories your body will burn through in a day even if you're in a coma for 24 hours. The problem is, even the most sedentary among us are not, in fact, in a coma. This number is the bare minimum your body needs for survival. What we really need to figure out is your AMR (Active Metabolic Rate). However, to get to the AMR, we must first calculate your BMR.
Now comes the math. If you don't know your BMR, it's influenced by a number of factors, including age, weight, height, gender, etc. etc. Because of these varying factors, we can't calculate your BMR to the precise calorie, but we can get extremely close. Here are some formulas for figuring out your BMR. Get out your calculator and plug your numbers into whichever formula applies to you.
MALE: 66 + (6.3 × body weight in pounds) + (12.9 × height in inches) − (6.8 × age in years)
FEMALE: 655 + (4.3 × weight in pounds) + (4.7 × height in inches) − (4.7 × age in years)
For me, this formula looks like 655 + (4.3x137) + (4.7x65) - (4.7x31). That becomes (655 + 589.1 + 305.5) - 145.7 = 1402.1. So my BMR is 1402 calories per day. Save your BMR-you will need to recalculate it every time you lose or gain 10 pounds, by the way!!
Now we need our AMR. Our AMR is influenced by our activity level during the day. THIS DOES NOT INCLUDE THE EXERCISE YOU DO IN A DAY! I'm talking about what your day looks like, without any exercise added in. What do you do all day? Check out the examples below (courtesy of JillianMichaels.com) and select your activity level and the corresponding score.
a. Sedentary Physical Activity Level
Do you have a desk job or do some other kind of work that keeps you in your chair for most of the day? If the answer is yes, your score is 1.1.
b. Light Physical Activity Level
Are you on your feet and walking around for at least half the day? Stay-at-home moms, salespeople, and doctors fall into this category. If this is you, your score is 1.2.
c. Moderate Physical Activity Level
If you're on the move pretty much all day, with a few limited periods of being sedentary, this is the level for you. People in this category include gardeners, carpenters, and mail carriers. If you're in this category, your score is 1.3.
d. High Physical Activity Level
Does your job require being constantly on the move, and does it entail significant amounts of manual labor? Construction workers, farm workers, and movers are among those who land in this category. If you're in this group, your score is 1.4.
So, I'm in the A category (be honest, people, I am!). I sit almost all day long. Oh, sure, on my weekends I can be pretty busy cleaning the house, but overall, I'm pretty sedentary. So my score is 1.1.
So, we take our score, and we multiply our BMR times our score. So for me, 1402x1.1=1542. This is how many calories I actually use up in an average day, without working out at all. Again, every 10lbs of weight loss or weight gain, you MUST recalculate BMR and AMR! Remember that and revisit this blog for your numbers.
So now you know how many calories it takes to keep you going. Science tells us that lowering our caloric intake beneath 1200 calories per day is very unhealthy, and will cause our metabolism to shut down, stopping us from losing weight. So you can't eat less than 1200 calories per day. But, if like me, your AMR is only 1542, that means the most I can cut my calories back is by 342 calories per day, or 2394 calories per week. That's not even a POUND of weight loss per week! :(
Ahhh, but wait! This is where exercise comes in, right? So if I want to lose a pound of weight per week, that means I need to exercise enough to burn another 158 calories per day. If I want to lose two pounds of fat per week, I need to burn another 658 calories per day with exercise! So...how do I know how much I'm burning?
Max and Target Heart Rates
First, we need to figure out our Max and Target heart rates, MHR and THR. This is a much simpler equation. Your MHR is quite simply 220 minus your age. So 220-31 (for me) is 189. In theory, this is the highest my heart rate will climb without sending me into cardiac arrest. Now, don't freak yourselves out. In reality, I've had my heart rate up this high, AND a good deal higher, back when I was very fat and unfit and working out hard. It won't kill you, but if you're older and/or in really bad shape, this is NOT a number you want to hit! Ideally, you want to work out between 75% and 85% of your maximum heart rate. 85% is really the golden ticket! So, take your MHR and multiply it by .85. So for me, 189x.85=161 (rounded up, you can't have a fraction of a heartbeat per minute ;). So that means my Target Heart Rate (THR) is 161 beats per minute. I want to be working out hard enough that my heart is beating at 161 beats per minute for the duration of my workout! I will burn the optimum number of calories at this heart rate! It helps to know what the low end of my target is, too, so I'll also multiply my MHR by .75 (189x.75=142). So now I know that, for a range, I want my heart rate to never fall below 142bpm, but to optimally maintain around 161 bpm, and to never go over 189bpm. Ta-da! Now go get yourself an inexpensive $10.00 wristwatch-style heart rate monitor and start exercising, keeping an eye on your heart rate while you work out!
Calories Burned During Exercise
The final part of this weight loss equation is how many calories you burn every minute of exercise. This is very strictly a function of your heart rate during said exercise. While many factors influence your caloric burn, a large group of scientists got together and did some extensive testing and published their findings in the Journal of Sports Sciences. They've included the formulas they used to find the caloric burn (per minute) of exercise, and I'll repost them here and walk you through them. But first, part of the equation is your weight, and they use weight in Kilograms, not Pounds, so we need to convert your weight. A pound is equal to 0.45359237 kilograms. So take your weight and multiply it by 0.45359237. For me, that's (137x0.45359237=62.14215469 kilograms). Save this number. You will need to recalculate these equations for every 10lb weight change, too! I know, bummer :)
The equations for calories burned per minute are as follows:
Men: C/min = (-55.0969 + 0.6309 x HR + 0.1988 x weight + 0.2017 x age) / 4.184
Women: C/min = (-20.4022 + (0.4472 x HR) - (0.1263 x weight) + (0.074 x age)) / 4.184
So, again, using myself as an example: C/min = (-20.4022 + (0.4472x161) - (0.1263x62.14215469) + (0.074x31)/4.184
Simplified: C/min = (-20.4022 + 71.9992 - 7.848554137347 + 2.294)/4.184
Again: C/min = (36.5879)/4.184=11.00.
Eleven calories per minute is what I burn when I keep my heart rate at 161bpm (my THR). That means in an hour of working out at that rate, I can burn 660 calories!
Ok, now, if that calculation for energy expenditure killed you, and I know it kills me, there has been a very kind person who has created a webpage with the calculator online already for you! Go here: http://www.braydenwm.com/calburn.htm and punch in the information as requested, and voila! Instant calories burned for your workout!
Putting It All Together
Ok, so now we have the info we need to lose weight!!
We know we (I) burn 1542 calories in a day, and that I can eat as little as 1200 calories per day, leaving me with a caloric deficit of 342 calories/day or 2394 calories/week. If I want to lose one pound per week, I need to burn another 158 calories per day through exercise. We also know that if I work out at my THR, I can burn 11 calories per minute. That means I need to spend at least 15 minutes per day working out at my THR (this does NOT include the warmup and cooldown!) to burn 500 calories per day, or to lose 1 pound per week!
If you want to lose weight faster, work out more! If you want to eat more calories, work out more to make up the difference! You see how this works? Great!
Now, get out there and START BURNING UP THAT FAT! Sorry to make you think, people. But now...JUST GO! :)
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