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.
