Originally posted by Hoss on fitness.com, posting here for your information:
The first step is establish how many calories you need to maintain your weight while resting. This is called your BMR. The following equations can be used to figure out your BMR:
“English BMR Formula”Women: BMR = 655 + ( 4.35 x weight in pounds ) + ( 4.7 x height in inches ) - ( 4.7 x age in years )
Men: BMR = 66 + ( 6.23 x weight in pounds ) + ( 12.7 x height in inches ) - ( 6.8 x age in year )
“Metric BMR Formula”Women: BMR = 655 + ( 9.6 x weight in kilos ) + ( 1.8 x height in cm ) - ( 4.7 x age in years )
Men: BMR = 66 + ( 13.7 x weight in kilos ) + ( 5 x height in cm ) - ( 6.8 x age in years )
This is just a general estimation, some may be above or below this, but this is a good place to start.
Multiply this number by your activity level factor:
1.0 - Sedentary (doing nothing all day)
1.2 - Very light activity (Working a desk job or on a computer and not performing any type of physical activity during your day.)
1.4 - Light activity (having a non-physical job (desk, computer, etc.) but performing some sort of physical activity during the day (e.g. above average walking) but no hard training.)
1.6 - Moderate activity (having a non-physical job, performing some sort of physical activity during the day, and including a daily workout session in your routine. This is where most of you are at.)
1.8 - High activity (either training plus a physical job or non-physical job and twice-a-day training sessions)
2.0 - Extreme activity (a very physical job and daily hard training.)
Now you have your daily maintenance calories.
Now that you know how many calories it takes to maintain your weight - how many should you eat to achieve your goals?
Well, the general rule of thumb is +/- 500. Plus 500 to gain, minus 500 to lose. However, it can be a better idea to go by percentages, +/- 20% of your maintenance. Remember, if you’re trying to bulk and eat too much - you will gain fat instead of muscle. If you’re trying to lose fat and eat too little, your body will hold on to the fat you have for dear life. Moderation, dear readers, moderation.