So it’s often said that calories in < calories out and you’ll lose weight. That’s pretty easy right? Well guess what, it’s not exactly that simple all the time. There are some things you should calculate to figure out exactly how many calories you should be shooting for – I think this is something that programs like Weight Watchers simplify with their points system and your point goals that you set.
So, what is basal metabolic rate? Well here is what Wikipedia defines it as:
Basal Metabolic Rate (BMR), and the closely related resting metabolic rate (RMR), is the amount of daily energy expended by animals at rest. Rest is defined as existing in a neutrally temperate environment while in the post-absorptive state. In plants, different considerations apply.
The release of energy in this state is sufficient only for the functioning of the vital organs, the heart, lungs, nervous system, kidneys, liver, intestine, sex organs, muscles, and skin.
http://en.wikipedia.org/wiki/Basal_metabolic_rate
The Wikipedia article also has some fairly in depth equations for calculating this. To save some time I’ve put together an Excel spread sheet. Click here to view it.
So a simple walk through of the spread sheet, you need to enter in your weight, height, and age. The sheet calculates the rest for you. The “Calculated BMR” that shows up in fields A4 and A5 is calculated for your “at rest” body functions. As you add activity your daily calories need increase. For simplicity sake, I defined the activity levels as follows:
Sedentary – desk job, you walk less than say 8,000 steps per day
Light Activity – desk job, walk less than 12,000 steps per day, light exercise (heart rate not over 120 bpm for 30 min per day)
Moderate Activity – walk less than 15,000 steps per day, light/moderate exercise (heart rate between 120-140 bpm for 30-45 min per day)
Very Activy – Moderate/heavy exercise (heart rate between 130-150 bpm for 30-60 min per day)
Training – you’re a pro (and I’m jealous)
As an example, at the start of my lifestyle change I was approximately 225 pounds so my BMR looked like this:
| 225 |
Weight (lbs) |
| 70 |
Height (Inches) |
| 30 |
Age (yrs) |
| 2182.5 |
Calculated BMR (Male) |
| 1810.5 |
Calculated BMR (Female) |
I considered my life at the very sedentary and the sheet showed me at 2619 calories/day to sustain my weight. In order to lose weight I had to drop approximately 1000 calories (500 calories to drop 1 lb/wk and 1000 to drop 2.5 lbs/wk). I’ll need to find where I got the 500/1000 calorie rule of thumb as I don’t think that is good or valid advice for anyone with a BMR under 1,500 calories.
Here is my what my current BMR looks like:
| 150 |
Weight (lbs) |
| 70 |
Height (Inches) |
| 30 |
Age (yrs) |
| 1710 |
Calculated BMR (Male) |
| 1488 |
Calculated BMR (Female) |
I consider my activity level somewhere between sedentary and light so my intake needs to be between 2,052 and 2,223 calories per day to sustain this weight.
At any rate, I hope it’s easier to get an idea of what it means to say you need to eat less calories than you expend now. It doesn’t mean starve yourself, but it does mean that you’ll probably want to add exercise to your routine and cut some food out of your eating habits.