If your goal is to burn more calories than you take in, you need to determine how many calories your body needs on an average day. So get your pen and paper out and I will help you determine yours! There is a mathematical formula I use to make this estimate. I say an estimate because although this calculation can be helpful it does not take into account genetics, age and muscular makeup all of which play a factor in your calorie burn rate.
I will run through the numbers with a hypothetical 155 lb woman so that you can see how the calculations work.
Take your weight and multiply by ten. This is the number of calories your body needs just to keep breathing and digesting and all the other maintenance work. It’s called your Basal Metabolic Rate (BMR). 155lb x 10 – 1,550 calories (BMR)
Determine your activity level. An average activity level is .30 (desk job, no exercise); more active is .40; very active is .50 and extremely active is .60 (engages in vigorous planned sports 5 to 7 times a week).
Multiply your BMR by your activity level. Here we will assume a .30 activity level. 1,550 x .30 = 465 (activity factor)
Add your BMR and your activity factor to get your maintenance calories. You need about this many calories to make it through an average day. If you eat this amount of calories you will maintain your current weight. 1,550 +465 = 2,015 (maintenance calories). So, for our 155 lb woman to maintain weight she would need to eat 2,015 maintenance calories a day. If you want to lose weight you have to eat fewer calories than your maintenance calories. Eating 1,800 calories a day will result in weight loss: 2,105 – 1,800 = 215 weight loss calories.
In order to lose 1 lb of fat you need to accrue 3, 500 weight loss calories. In our example the 215 weight loss calories spent per day adds up to 78,475 weight loss calories per year. This yields a weight loss of 22 lbs a year. The greater the difference between your maintenance calories and your actual calories, the faster you will lose weight. As an important note, never go below 1,200 calories per day. Your metabolism will slow and you will be more likely to binge due to starvation.
Remember, if you increase your maintenance calories by upping your activity level you’ll also speed up weight loss. It is really best to do a combination of both: reducing calories and upping activity level. You will always see better weight loss results by bumping up your activity level rather than just reducing calories; it gives your metabolism a real boost! Also remember that as you lose weight or increase your activity level you will need to perform these calculations again based on your new numbers.