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2007/03/30, 12:27 PM
One of the most important aspects of fat loss or gaining weight (if you have a high metabolism rate) is knowing what your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE) is so you know how you need to adjust your diet for ultimate effect in reaching your goals.
WARNING: The following is pretty length but contains a lot of information and calculators to determine BMR and TDEE. Knowing these can help bring you that much closer to attaining the weight you want.
Enjoy!!!
For accuracy and continual monitoring of your diet, you should calculate how many calories you burn in a day; this is called your Total Daily Energy Expenditure (TDEE). The nutrition plan developed by FT.com should help you with this as well. Yet, as an educational tool, you will learn how to calculate this yourself for continual monitoring as your physical condition changes over time.
TDEE is the total number of calories that your body expends in 24 hours, including all activities. TDEE is also known as your "maintenance level". Knowing your maintenance level will give you a starting reference point from which to begin your diet. According to popular exercise physiologists, the average maintenance level for women in the U.S. is 2000-2100 calories per day and the average for men is 2700-2900 per day.
These are only averages; caloric expenditure can vary widely and is much higher for athletes or extremely active individuals. Some triathletes and ultra-endurance athletes may require as many as 6000 calories per day or more just to maintain their weight! Calorie requirements may also vary among otherwise identical individuals due to differences in inherited metabolic rates.
METHODS OF DETERMINING CALORIC NEEDS
There are many different formulas you can use to determine your caloric maintenance level by taking into account the factors of age, sex, height, weight, lean body mass, and activity level. Any formula that takes into account your Lean Body Mass (LBM) will give you the most accurate determination of your energy expenditure, but even without LBM you can still get a reasonably close estimate.
The ?quick? method (based on total bodyweight):
A fast and easy method to determine calories needs is to use total current body weight times a multiplier.
Fat Loss = 12-13 calories per lb. of bodyweight
Maintenance (TDEE) = 15-16 calories per lb. of bodyweight
Weight Gain = 18-19 calories per lb. of bodyweight
This is a very easy way to estimate caloric needs, but there are obvious drawbacks to this method because it doesn?t take into account activity levels or body composition. Extremely active individuals may require for more calories than this formula indicates. In addition, the more lean body mass one has, the higher the TDEE will be. Because body fatness is not accounted for, this formula may greatly overestimate the caloric needs if someone is extremely over fat. For example, a lightly active 50-year old woman who weighs 235 lbs. and has 34% body fat will not lose weight on 3000 calories per day (235 X 13 as per the ?quick? formula for fat loss).
EQUATIONS BASED ON BMR.
A much more accurate method for calculating TDEE is to determine Basal Metabolic Rate (BMR) using multiple factors, including height, weight, age and sex, then multiply the BMR by an activity factor to determine TDEE. BMR is the total number of calories your body requires for normal bodily functions (excluding activity factors). This includes keeping your heart beating, inhaling and exhaling air, digesting food, making new blood cells, maintaining your body temperature and every other metabolic process in your body. In other words, your BMR is all the energy used for the basic processes of life itself.
BMR usually accounts for about 2/3 of total daily energy expenditure. BMR may vary dramatically from person to person depending on genetic factors. If you know someone who claims they can eat anything they want and never gain an ounce of fat, they have inherited a naturally high BMR. BMR is at its lowest when you are sleeping undisturbed and you are not digesting anything. It is very important to note that the higher your lean body mass is, the higher your BMR will be. This is very significant if you want to lose body fat because it means that the more muscle you have, the more calories you will burn.
Muscle is metabolically active tissue, and it requires a great deal of energy just to sustain it. It is obvious then that one way to increase your BMR is to engage in weight training in order to increase and/or maintain lean body mass. In this manner it could be said that weight training helps you lose body fat, albeit indirectly.
THE HARRIS-BENEDICT FORMULA (BMR BASED ON TOTAL BODY WEIGHT)
The Harris Benedict equation is a calories formula using the factors of height, weight, age, and sex to determine basal metabolic rate (BMR). This makes it more accurate than determining calorie needs based on total bodyweight alone. The only variable it does not take into consideration is lean body mass. Therefore, this equation will be very accurate in all but extremely muscular (will underestimate caloric needs) and the extremely over fat (will overestimate caloric needs).
Men: BMR = 66 + (13.7 X wt in kg) + (5 X ht in cm) ? (6.8 X age in years)
Women: BMR = 655 + (9.6 X wt in kg) + (1.8 X ht in cm) ? (4.7 X age in years)
Note: 1 inch = 2.54 cm.
1 kg = 2.2 lbs.
Example:
You are female
You are 30 years old
You are 5?6? tall (167.6 cm)
You weight 120 lbs (54.5 kilos)
Your BMR = 655 + 523 + 302 ? 141 = 1339 calories/day
Now that you know your BMR, you can calculate TDEE by multiplying your BMR by your activity multiplier from the chart below:
ACTIVITY MULTIPLIER
Sedentary = BMR X 1.2 (little or no exercise, desk job)
Lightly Active = BMR X 1.375 (light exercise/sports 1-3 days/wk)
Moderately Active = BMR X 1.55 (moderate exercise/sports 3-5 days/wk)
Very Active = BMR X 1.725 (hard exercise/sports 6-7 days/wk)
Extremely Active = BMR X 1.9 (hard daily exercise/sports & physical job or 2X day training, i.e.
marathon, contest, etc.)
Example:
Your BMR is 1339 calories per day
Your activity level is moderately active (work out 3-4 times per week)
Your activity factor is 1.55
Your TDEE = 1.55 X 1339 = 2075 calories/day
KATCH-MCARDLE FORMULA (BMR BASED ON LEAN BODY WEIGHT)
If you have had your body composition tested and you know your lean body mass, then you can get the most accurate BMR estimate of all. This formula from Katch & McArdle takes into account lean mass and therefore is more accurate than a formula based on total body weight. The Harris Benedict equation has separate formulas for men and women because men generally have a higher LBM and this is factored into the men?s formula. Since the Katch-McArdle formula accounts for LBM, this single formula applies equally to both men and women.
BMR (men and women) = 370 + (21.6 X lean mass in kg)
Example:
You are female
You weight 120 lbs. (54.5 kilos)
Your body fat percentage is 20% (24 lbs. fat, 96 lbs. lean)
Your lean mass is 96 lbs. (43.6 kilos)
Your BMR = 370 + (21.6 X 43.6) = 1312 calories
To determine TDEE from BMR, you simply multiply BMR by the activity multiplier:
Example:
Your BMR is 1312
Your activity level is moderately active (workout 3-4 times per week)
Your activity factor is 1.55
Your TDEE = 1.55 X 1312 = 2033 calories
As you can see, the difference in the TDEE as determined by both formulas is statistically insignificant (2075 calories vs. 2033 calories) because the person we used as an example is average in body size and body composition. The primary benefit of factoring lean body mass into the equation is increased accuracy when your body composition leans to either end of the spectrum (very muscular or very obese).
ADJUST YOUR CALORIC INTAKE ACCORDING TO YOUR GOAL
Once you know your TDEE (maintenance level), the next step is to adjust your calories according to your primary goal. The mathematics of calorie balance is simple: To keep your weight at its current level, you should remain at your daily caloric maintenance level.
To lose weight, you need to create a calorie deficit by reducing your calories slightly below your maintenance level (or keeping your calories the same and increasing your activity above your current level). To gain weight you need to increase your calories above your maintenance level. The only difference between weight gain programs and weight loss programs is the total number of calories required.
NEGATIVE CALORIE BALANCE IS ESSENTIAL TO LOSE BODY FAT.
Calories not only count, they are the bottom line when it comes to fat loss. If you are eating more calories than you expend, you simply will not lose fat, no matter what type of foods or food combinations you eat. Some foods do get stored as fat more easily than others, but always bear in mind that too much of anything, even ?healthy food,? will get stored as fat.
You cannot override the laws of thermodynamics and energy balance. You must be in a calorie deficit to burn fat. This will force your body to use stored body fat to make up for the energy deficit. There are 3500 calories in a pound of stored body fat. If you create a 3500-calorie deficit in a week through diet, exercise or a combination of both, you will lose one pound.
If you create a 7000-calorie deficit in a week, though not recommended, you will lose two pounds. The calorie deficit can be created through diet, exercise or preferably, with a combination of both. Because we already factored in the exercise deficit by using an activity multiplier, the deficit we are concerned with here is the dietary deficit.
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HARDWORK SPOTLIGHTS THE CHARACTER OF PEOPLE: SOME TURN UP THEIR SLEEVES; SOME TURN UP THEIR NOSES; AND SOME DON\'T TURN UP AT ALL.
GOD GAVE US TWO EARS AND ONE MOUTH; FOR THE SAKE OF HELPING OTHERS, USE THEM IN THAT PROPORTION.
Be good to your body, it is the only place you HAVE TO LIVE! STAY THE COURSE!!
Andrew Williamson,
Lieutenant Commander
U.S. Coast Guard
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