How accurate are weight loss calculators?

weight loss calculators genetix weight loss

Weight Loss Calculators

In the world of weight loss, many people seem to finally be making a good effort in taking care of it the right way—with proper, balanced nutrition, and exercise.  With that being said,  many of these same people don’t know exactly where to start when it comes to how many calories in fat, protein, and carbs they should be getting, how high their heart rate should be when exercising aerobically, what their proper BMI goal should be, etc.  So, technology has—via the world wide web, and smart phone apps—made it convenient for a regular Joe to download a calculator to give them answers to those questions.  My question to you is, do you think that these calculators are accurate?

The short answer to this is “No.”  However, the slightly longer answer is “Yes, but…”

Let’s get into the latter.  A person has to keep in mind that these calculators are tools based on AVERAGES.  This is a good starting point because most people tend to fall into that category, but, of course, every BODY is unique.  Calculators don’t take into effect body COMPOSITION (and you absolutely can NOT get accurate body composition with any calculator, trust me).

BMI Calculator

Let’s talk about one of the most common weight loss calculators people use: The BMI calculator.  The formula for BMI is weight (in pounds) divided by height squared (in inches) times 703, or weight (kg) over height squared (m).  So, a woman who is 5’7″ (67 inches) and weighs 145 lbs has a calculated BMI of 22.7, which, according to BMI charts, is actually smack in the middle of the normal weight range.

However, what the formula doesn’t take into account is muscle mass vs. fat mass, which might actually move that BMI number up or down, depending on how much of either mass a person has.  It’s good to get a body composition test done (this can be done by a doctor or even a properly trained fitness professional) in order to obtain more accurate results.

Another common calculator people use is the one fixed right into their treadmill, which calculates how many calories are burned during their workout. Again, this calculator works based on averages, but doesn’t take into account an individual’s fitness level, their muscle mass (which can burn even more calories), or the calories that are naturally burned before and after exercise.

Target Heart Rate (THR)

Another common calculation is the THR (Target Heart Rate) formula, which estimates roughly how many beats per minute your heart should be going during a workout at a chosen percentage of your maximum heart rate (say that 5 times fast!)  This is an important number to know, as it will determine at what rate you should work to get the best possible results from (typically) an aerobic workout.

The standard formula to find your maximum heart rate is 220 minus your age, and then you get your THR by multiplying that number by the percent you should be working.  For example, I’m 32, so my max heart rate is then 188, and when I train on a treadmill, I do intervals that go 65%-85%, so my heart rate should alter between 122 and 159, not going below, and not going above.  Sounds good, right?  Except, again, some people are not in the shape of the average person their age, whether that be for the better or worse, and therefore should take into consideration.

A Better Way: The Karvonen Method

A much better method to use would be the Karvonen method, as this takes into account your RESTING heart rate, which gives a better indication of your fitness level.

There are many other calculators people use to help them reach their target weight and fitness level, and one day, science and technology MAY be good enough for these to be accurate and effective for every individual.  But for now, whenever you use any kind of calculator, whether it be for how many calories you should consume daily, or how much body fat you might have, just take into account that while they can be a decent enough guideline, they are not the rule.  You should always consult your doctor, health coach, fitness professional, or dietitian before making drastic changes to your diet or routine, so that they can help you better identify, based on YOUR individual lifestyle and body type, how to attain your best results.

What kind of weight loss calculator do you use? Is it a smart phone app? Does your scale at home calculate your BMI? How accurate do you find these to be?

Genetix Program’s team of doctors, certified coaches/trainers and nutritionists can help you make healthier lifestyle choices through daily phone coaching to achieve lasting weight loss. You can do it and we can help!

Author: Rachel Eisner

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