Calculating Your BMR: How Many Calories Do You Need?
After looking over one of my food and exercise logs, Donna B. wondered what BRM was. Well, it’s a typo. I meant to type BMR, which stands for basic metabolic rate. That’s the number of calories your body needs just to live and maintain minimum functions, assuming you didn’t move a muscle all day (e.g., you slept).
Although I’d answered Donna in the comments, she pointed out that this is useful information for those of us trying to diet rationally. So, at her suggestion, I’m sharing that here with you, too.
When it comes to dieting, your individual BMR is the single most important number to determining how many calories you should be getting (or not) per day. Many of us have a tendency to cut calories back too far in the hope of speeding up weight loss. But when you understand your BMR is what’s needed just to keep your lungs and heart working, well, you can see why your body’s metabolism will slow down if you aren’t eating enough calories for those functions along with your other activities.
Ultimately, calculating BMR is a complicated mathematical equation that’s well beyond me:
Yeah. Er, I just use a BMR calculator.
Once you know your BMR it’s easy to figure out how many calories you need to maintain your current weight at your current level of activity:
- Sedentary (little or no exercise) : Calorie-Calculation = BMR x 1.2
- Lightly active (light exercise/sports 1-3 days/week) : Calorie-Calculation = BMR x 1.375
- Moderately active (moderate exercise/sports 3-5 days/week) : Calorie-Calculation = BMR x 1.55
- Very active (hard exercise/sports 6-7 days a week) : Calorie-Calculation = BMR x 1.725
- Extremely active (rigorous hard exercise/sports & physical job or 2x training) : Calorie-Calculation = BMR x 1.9
So, if you’re trying to lose weight you take your BMR x (whatever your number is) and subtract 15-20% to get the number of calories you should eat in a day. Cut back beyond that and you’ll stall your metabolism, along with putting your health at risk. Eat too much more than that and, well, you just aren’t going to lose weight no matter how much you try to convince yourself otherwise.
Just keep in mind it’s not safe to go below 1200 calories per day for women, or 1800 calories per day for men. If that’s where your BMR x (whatever your number) – 15-20% takes you then it’s time to give serious thought to upping your activity level.
4 Responses to “Calculating Your BMR: How Many Calories Do You Need?”
Looking back, I think this BMR factor is what screwed up the results of my bariatric surgery. Sure, I lost weight and lost it fast. Getting only 500 or so calories a day will do that.
To a point. Then the slowed metabolism kicks in. And it’s really quite hard to get it back up when you can’t eat enough to handle increased activity.
Extreme dieting really is dangerous and is likely to make you fatter and less fit than before you started.
That could very well be the case, Donna. I’m so sorry the surgery didn’t work for you, because I imagine you’ve been beating yourself up for a while now thinking it’s your fault.
Honestly, I don’t think that it is. Now, at the risk of sounding like Glenn Beck, I should say here that I’m not a doctor but I am a thinker, and to me the whole idea behind bariatric is sound: lower the body’s ability to take calories in and it *should* turn to burning off stored energy (fat) to make up the difference.
But I can’t help wonder, doesn’t that notion ignore the reality most of us live with?
What I mean is that those of us who get overweight have already demonstrated that our bodies aren’t efficient at turning to their own fat deposits for fuel. Otherwise we’d see more rapid weight loss on fad diets (like the cabbage soup diet, for instance).
Oh, sure, we have an initial rapid loss but, as you probably know from experience (I sure do), that’s primarily water. Thing is, there’s very little water in body fat.
It stands to reason, then, that the bodies of some overweight women don’t react to a plunge in caloric intake by looking for energy in all the wrong places (cue an old song here), like our muscles, which have the highest water content but also metabolise the most calories.
All of which is to say that, yeah, dramatically lowering caloric intake — whether through bariatric surgery or stringent dieting — should in theory help with weight loss but in practice actually work against that very goal.
And as you no doubt noticed, post-surgery patients who can’t even consume enough calories to feel energetic *also* can’t engage in the exercise needed to preserve (much less build) muscle mass, the one thing that might work with them to get past that metabolic slow down.
Anyway, I’m not a doctor (I don’t even play one on TV), but I have to agree with you: extreme dieting paves the way for even greater weight loss and a far more difficult time ahead when you decide to work all that weight off.
Guess we’ll just have to keep each other motivated, eh?
I’ve been beyond being motivated to lose weight in the past several years and have really just concentrated on getting some strength back and not gaining back any more weight.
Part of that is my age, I simply don’t care as much how I look and I’ve never cared a great deal about fashion. I’m fond of the baglady look
I have a feeling celiac is going to motivate you mightily. You’ve got to change so many of your eating habits because of it, that I think you’ll be successful in changing caloric intake right along with it.
2280, hmm, guess I can live with 1825, since I’m not even doing that right now. Best wishes on your plans. Patience is the secret.