A lesson on BMR, creating a calorie deficit, and what the heck “NET” calories means
Okay, so every single human being and animal has something called a BMR. This stands for basal metabolic rate (some may call it resting metabolic rate). Your BMR is the amount of energy your body expends daily, simply at rest. We all know calories are just a unit of energy, so to equate our BMR, we calculate it in terms of calories. Basically, if you were to be in a coma, your BMR is how many calories your body would burn just laying on the ventilator. You do not have to expend any extra energy to burn those calories.
So, what the heck is YOUR BMR and why do you have to eat that much? Well first, calculate your own BMR using this site. To help explain better, I will use my own BMR for an example. When using that site, I calculate my BMR out to be 1688.3 calories. This number is often lower than your true BMR, especially if you are a fairly active person. As you exercise more, your body burns calories (and provides you with energy) more effectively, so your metabolic rate increases. Now you want to multiply this number by how active you are. This will give you how many calories you should be eating every day to maintain your current weight. So if you’re just starting out on this journey and you have lived a fairly sedentary lifestyle until now (no exercise or sports, not working a job that requires being on your feet most of the day), then you will multiply your BMR by 1.2. If you are a lightly active person (you work a job that requires a lot of standing, you’re usually on your feet 1-3 days a week), then multiply your BMR by 1.375. If you are moderately active (you’ve been on this journey for awhile and tend to jog, bike, or use the elliptical 3-5 days a week) then you will multiply your BMR by 1.55. If you’re very active (you do hard exercise and/or sports 6-7 days a week consistently and have been doing so for awhile), you will multiply your BMR by 1.725. If you are an athlete (very hard exercise and/or sports every day as well as sports training; basically you never sit down and are working out 10+ hours a day), then you multiply your BMR by 1.9.
So, you can use the above equation to get your daily caloric needs, or some people, myself included, do not like to use that part of the equation because they use a tracker like myfitnesspal, which calculates the calories you burn in your workout every day for you. The most effective way to calculate your burn during your workout is to invest in a heart rate monitor. When your heart rate is elevated, you’re burning more calories. That’s how those machines at the gym determine how many calories you’re burning: they take the average person (155 pounds), and what their heart rate would be at the level, resistance, and speed you’re going at. So obviously, if you’re not 155 pounds, or if you’re going at a level that’s easier for you than someone who’s never worked out before, your heart rate is going to be different from the “average” that these machines provide. Take the number of calories burned according to the machine (or even according to myfitnesspal) as a close “guess-timation.”
So let’s go back to my example of my BMR, 1688.3. We’re going to round it to 1690 to make it easier. In my daily workout, I often burn (according to myfitnesspal) around 600 calories. So let’s say today I went to the gym and burned that 600. If I wanted to maintain my current weight, then today I would need to eat 1690 + 600 = 2,290. Sounds like a lot of calories? That’s how much energy I need to keep my body healthy and active. If I don’t eat enough, then my body is going to find other ways to provide me with energy, like breaking down all of my muscle, lowering my metabolism so I don’t burn through my food so quickly, and making me weak to signal to my brain that I need more food.
But I’m trying to lose weight! So what do I do if I want to lose weight? Healthy weight loss consists of losing 1-2 pounds per week. Slower, steady weight loss has been proven to show long-lasting results, less excess skin, and concrete, healthy habits. So how many calories do I need to burn to lose one pound of fat? 3500 calories is equal to one pound of fat. Here’s where it gets a bit tricky, so try to stay with me. Since there are 7 days in one week, we’re going to easily divide 3500 calories by 7. That gives us 500 calories. That means every day this week, I want to have an excess burn, or “deficit” of 500 calories. Let’s go back to my calorie consumption. I burned 600 calories today, so if I didn’t want to lose any weight, I would need to eat 2,290 calories. Since I’m trying to lose weight, I’m going to subtract 500 calories from my calorie goal of 2,290. That gives me a grand total of 1,790 calories. So for the entire day, my calorie consumption should equal out to 1,790 calories. To some, that may sound like a lot, but my body is working hard to provide me with energy, so I need to fuel it back up.
So what’s up with myfitnesspal only giving me 1200 calories? Myfitnesspal has to cater to thousands of people, so they set their baseline at a number that already creates the calorie deficit for you. Let me repeat that, if you did absolutely nothing the whole day and did not work out, the calories myfitnesspal gives you (1200) is what you NEED to eat just to sustain your body, AS WELL AS LOSE WEIGHT. For those of you who have a myfitnesspal account, click on the link labeled goals. It will take you to a page where it breaks down your calorie deficit for you. Here is a picture of mine:
According to myfitnesspal (again, guess-timations), my natural caloric burn every day is 2,180 calories. I set my baseline calorie consumption at 1300 calories. So even if I were to not work out and barely move the whole day, I would still create a 880 calorie deficit. If I eat exactly 1300 calories every day, without working out, it is projected that I will burn 6,160 calories in one week, which equals out to a 1.8 pound weight loss. This is why you need to eat back the calories you burn in exercise. BECAUSE FOR THE VAST MAJORITY, 1200 CALORIES IS THE BARE MINIMUM TO SUSTAIN YOUR BODY AND STILL LOSE WEIGHT AT THE SAME TIME. I encourage most of you to up your myfitnesspal calorie goal if you feel a NET calorie goal of 1200 is too low (to do so, go back to that Goals tab, and click the green “change goals” button. Then choose the custom button instead of guided, and it will let you input how many net calories you wish to consume).
What happens if I don’t eat 1200 net calories every day? Your body is smart, and it will recognize that it’s not getting the fuel it needs. It will go into something called starvation mode, where your body wants to protect itself from starving and dying. It will break down your muscle, slow your metabolism, weaken your body, and eventually shut down your organs. Think of your body as a car; you can’t expect your car to move without fuel in it.
I know this seems like a lot to handle, but weight loss can be achieved if you fuel your body properly. If you find you’re eating your BMR with the deficit and you’re still not losing weight, go ahead and lower your calorie consumption by 100-200 a day. Every body is different and like I said, these are all guess-timations. As long as you don’t drop below 1200 net calories, you don’t need to worry about not eating enough. Eat well, eat enough, and exercise daily and you will see success.