If you’re looking for a way to lose weight that is guaranteed to work and that relies on simple science, then there is really only one method worth considering: calculate your AMR and BMR and then restrict your calories.
Many people reading that will already be outraged but before you storm off, hear me out. While it is certainly true that losing weight is a little more complicated than simply restricting your calories and while you need to think about your health as well as purely burning fat, it’s also the case that this is the only method you can use to actually guarantee weight will come off.
All will be explained though so don’t worry. First, let’s take a look at what your AMR actually is and why it’s such an important variable in the weight loss equation.
AMR stands for ‘Active Metabolic Rate’ and is closely related to your BMR, known as the ‘Basal Metabolic Rate’. The reason this is so important is that it tells you precisely how much energy you use throughout the day. This in turn means that you can ensure that the amount of energy you consume – in calories – is lower. As a result, you will lose weight.
Every single function in the human body requires calories. When you walk, run, jump, climb, breathe, sleep, blink or digest food your body uses something called ATP (adenosine triphosphate) which it largely gets from glucose in our food. If you have more glucose in your blood than you use for energy, some of that will get stored around the body as fat so that you can use it later. But if burn more energy than you consume, then your body will have to use existing fat stores as a source of energy.
Your BMR tells you how many calories it would require for you simply to remain alive. These are the calories used for breathing, blinking, beating your heart, breathing etc. Your AMR meanwhile tells you how many calories you burn in a typical day, adding on all your activity. This includes everything from walking to the kitchen to make tea, to doing intensive workouts.
There’s a lot more to your diet than just AMR and BMR. Your food is not just for energy and fuel but is also crucial for providing the building blocks to create tissue, hormones, enzymes and more. It’s crucial that you eat a diet that is filled with nutrients in order to maximize your health and your longevity and to reduce the likelihood of illness.
At the same time, simply counting calories doesn’t tell you the whole story. What is often forgotten is that different foods get absorbed more quickly into the bloodstream or have different effects on your metabolism. This can impact on the amount of calories that actually get stored as fat, as well as on your energy levels and appetite.
These are all variables to consider and that’s why it’s highly important to carefully consider all the implications of your diet. BUT with that said, keeping your caloric intake lower than your AMR is still the only guaranteed way to burn fat. If you burn more calories than you consume, then you will have to burn fat. And if you consume fewer calories than your AMR, then the absolute maximum that can reach your blood is still going to be lower than the amount you use during the day.
How to Calculate Your AMR and BMR
So with all that said, how do you go about working out your BMR and AMR? There is actually quite a simple equation that allows you to do this quickly and easily:
BMR = 66 + (6.23 x weight in pounds) + (12.7 x height in inches) – (6.8 x age in years)
BMR = 655 + (4.35 x weight in pounds) + (4.7 x height in inches) – (4.7 x age in years)
From here, you then simply need to increase that amount based on the amount of activity you do in a typical day. We are multiplying rather than adding because the exercise you are doing is simply going to ‘ramp up’ your existing metabolism to burn exponentially more as you become more active.
So take the score for your BMR and multiply it by:
1.2 if you’re sedentary (little or no exercise)
1.375 if you’re lightly active (you exercise 1-3 times a week)
1.55 if you’re moderately active (you exercise or work about average)
1.725 if you’re very active (you train hard for 6-7 days a week)
1.9 if you’re highly active (you’re a physical laborer or a professional athlete)
Once you have calculated this number, you can now calculate the amount of calories you consume on average in a day and start thinking of ways to bring that number down so as to maintain a consistent ‘deficit’.
Or you can use an online calculator such as the one here.
Is This Number Accurate?
The big question then is just how accurate the AMR and BMR are. Unfortunately, these are always going to be rough guides rather than exact numbers for a number of reasons.
Firstly, our activity levels change constantly from day to day.
Meanwhile, even things like mental activity or stress can impact on how many calories you’re burning in a given day.
Another issue to consider is the individual differences that come from things like your hormones and your metabolism. Many things can impact on how many calories you burn at any given time. If you have higher levels of testosterone for example then you’ll find that this causes you to burn more fat and build more muscle. Likewise, you’ll burn more fat if you have more muscle rather than more fat contributing to your overall weight.
Then there’s the possibility that you might have a condition affecting your hormone balance or metabolism. Women on oral contraceptives may notice this for example, as might those suffering with something like polycystic ovaries or even hypothyroidism.
For these reasons, your mileage may vary and so it’s important to monitor the impact of your diet changes and to alter your consumption accordingly. These numbers are most likely to be accurate for a mesomorph rather than an extreme ectomorph or endomorph, so take this into account!
Another way to look at your AMR is to look at an activity tracker which will be able to more accurately measure things like the number of calories you are burning during sleep and the impact of your heart rate. Note that this still isn’t a perfect figure however – apart from anything else, your heart rate is not the sole indicator of the calories you burn during a workout!
Don’t treat these numbers as verbatim then but rather see them as one more useful tool in the fight to lose weight fast!