BASAL METABOLISME RATE

BASAL METABOLISME RATE

Basal energy expenditure (BEE) or basal metabolic rate (BMR) as it is sometimes called, is the energy requirement to maintain life. It is measured at rest, but not asleep in a thermo-neutral environment in the post-absorptive state. It can be measured directly or indirectly, or it can be estimated as we are doing here. We are using the equations of Harris & Benedict (1919).The Harris-Benedict Equation for estimating one's BEE accounts for gender, age, height and weight. As the abstract below indicates, the BEE derived using this equation for obese people are somewhat overestimated. That is, the equation appears to be reasonably accurate for normal people with normal body fat (see research abstract below). Given that there were far fewer obese people around back in the early 1900s than there are today, you should be aware of this weakness.

To partially offset this inherent weakness, the calorie charts below are based on one's lean body weight (LBW means fat-free weight). The simple logic for doing this is that for any given body weight, the person with the lowest percentage of body fat is going to burn more calories. Bigger muscles burn more calories than do little ones. Thus, the assumption is made that for any given LBW in the tables below, the BEE is based on an average person with an average percentage of body fat. Since the Harris-Benedict equation uses total body weight, we are assuming that (for example) a woman with 100 pounds of lean body weight, and is 20% body fat, actually weighs 125 pounds. And a man with 170 pounds of lean body weight, and is 15% body fat, actually weighs 200 pounds.

For men, the B.E.E. = 66.5 + (13.75 x W) + (5.003 x H) - (6.775 x A)

For women, the B.E.E. = 655.1 + (9.563 x W) + (1.850 x H) - (4.676 x A)

Where:W = actual weight in kilograms (1 kg = 2.2046 pounds) H = height in centimeters (2.54 cm per inch) A = age in years

Reproduced with Permission:

Journal of the American Dietetic Association -- April 1998 Abstract -- The Harris-Benedict studies of human basal metabolism: History and limitationsDavid C. Frankenfield, MS, RD, Eric R. Muth, MS, and William A. Rowe, MD

ABSTRACTIn the early part of the 20th century, numerous studies of human basal metabolism were conducted at the Nutrition Laboratory of the Carnegie Institution of Washington in Boston, Mass, under the direction of Francis G. Benedict. Prediction equations for basal energy expenditure (BEE) were developed from these studies. The expressed purpose of these equations was to establish normal standards to serve as a benchmark for comparison with BEE of persons with various disease states such as diabetes, thyroid, and other febrile diseases. The Harris-Benedict equations remain the most common method for calculating BEE for clinical and research purposes. The widespread use of the equations and the relative inaccessibility of the original work highlights the importance of reviewing the data from which the standards were developed. A review of the data reveals that the methods and conclusions of Harris and Benedict appear valid and reasonable, albeit not error free. All of the variables used in the equations have sound physiologic basis for use in predicting BEE. Supplemental data from the Nutrition Laboratory indicates that the original equations can be applied over a wide range of age and body types. The commonly held assumption that the Harris-Benedict equations overestimate BEE in obese persons may not be true for persons who are moderately obese.

(J Am Diet Assoc. 1998;98:439-445.)

Based on data contain in: Harris J, Benedict F. A biometric study of basal metabolism in man. Washington D.C. Carnegie Institute of Washington. 1919.

Obviously, there is more to life than just resting in that temperature-neutral environment. You must also have energy from your diet to support your activities above basal. Once you have determined your BMR, you must estimate your actual metabolic rate. You do this by computing how many minutes you spend in your various activities each day, and adding the total caloric cost of these activities to your BMR.

To simplify this task, we have divided calorie burning activities into five levels from very light to very heavy. The results you derive are only an estimate, but should nonetheless give you an idea of your daily caloric needs.PRIVATEPhysical Activity And Its Caloric Cost

PRIVATEAverage Couch PotatoAverage Fitness BuffAverage Hard Training Athlete

Very LightLightModerateHeavyVery Heavy*

1.2 - 1.3 X BEE1.4-1.5 X BEE1.6-1.7 X BEE1.8-1.9 X BEE2.0+ X BEE

Reading Sitting Driving EatingWalking Sweeping Playing Piano Bicycling (easy).Fast walk Dancing Ping-Pong SkatingLight weight training. Swimming Running Bicycle Race BasketballBoxing Rowing Mountain climbingIntense weight training

* The caloric cost of highly intense activities such as Nordic skiing or marathon running may be more than double your BMR.

The higher your body fat percentage, the fewer calories you'll burn (lower activity level, and less muscle to burn calories). The lower your body fat percentage, the more calories you'll burn (bigger muscles burn more calories than little ones). Thus, it becomes much easier to get rid of fat permanently by increasing your metabolic rate. You do this by increasing both your muscle mass and your activity level. You can (and SHOULD) gain muscle mass and lose fat at the same time. Never sacrifice muscle tissue during the fat loss process. Instead, build more muscle to burn more calories. You'll lose more fat faster, and you'll be more likely to keep it off. The KEY is to control your calories!Average Daily Activity Level

To estimate your average activity level for a 24 hour period, read the INSTRUCTIONS below. You will easily be able to approximate the percentage that most closely describes your lifestyle. This percentage is used in the daily caloric expenditure charts below.InstructionsFor each of the 24 hours in one of your "average" days, determine your energy expenditure by reading the descriptions below. Then, multiply your hourly BEE (BEE divided by 24) times your energy expenditure. For example, if your hourly BEE equals 85 calories, and your activity level during that hour was light (1.3), then you simply multiply 85 times 1.3. Your hourly caloric expenditure equals 110.5 calories.

Do this for each hour of the day, add all of them together, and that is your daily caloric requirement (your metabolic rate). Be SURE to apportion your daily calories over at least five meals, with each meal reflective of your UPCOMING caloric needs. For example, if you expect to train, eat more; if you expect to take a nap, eat less.PRIVATEENERGY EXPENDITURE GUIDE

Multiply this number by BEEActivity Description

.8Sleeping

1.0Lying down totally relaxed but not sleeping (this is your "basal metabolic rate" or "basal energy expenditure)

1.2Very Light: Sitting, studying, talking, little walking or other activities.

1.3Light: Typing, teaching, lab/shop work, some walking.

1.4 -1.6Moderate: Walking, jogging, gardening type job.

1.7 -1.8Heavy: Heavy manual labor such as digging, tree felling, climbing.

1.9 - 2.0Exceptionally Heavy: Fitness-oriented cycling or similar vigorous activities, weight training, aerobic dance.

2.1 - 2.2Sports: Vigorous sports competition such as football, racquetball, tennis or other extended-play sports activities.

2.3 - 2.4All-Out Training: Extremely high intensity weight training with little rest between sets or exercises.

2.5Extended Maximum Effort: Extremely high intensity and high duration sports competition such as triathlon, cross country skiing or marathon.

The caloric expenditures listed in the table below are for people with about a 20 percent body fat level. The smaller your muscles are, the fewer calories you'll burn; the bigger your muscles are, the more calories you'll burn. That means that the higher your proportion of fat is to your total body weight, the fewer calories you'll burn. On the flip side of the coin, the greater your proportion of muscle to your total body weight, the more calories you'll burn. Remember that strenuous exercises with weights (including, but not limited to, dumbbells and barbells, Nautilus-type machines, your own body weight, and other forms of resistance exercises) is the best way to increase your muscle size, thereby increasing your metabolic rate. This will result in far more calories being burned all day long -- even at night while you're sleeping. This, in turn, makes it easier to keep your body fat level in check. PRIVATEActivities And Their Approximate Hourly Caloric Cost For Different Body Weights

If You Weigh...100125150175200225250275300

Light AerobicsWalking 2.5 Mph GardeningGolfLawn MowingLight CalisthenicsLight Weight TrainingHouse CleaningWalking 3.75 MphSwimming 2.5 MphMedium AerobicsBadmintonWood ChoppingMedium Weight TrainingSlow JoggingHeavy CalisthenicsHeavy AerobicsHeavy Weight TrainingMedium JoggingCycling 13 MphFast Jogging104104118145145172

172172199199240247294

342376444444

512512560580154154168195195222

222222249249290297344

392426494494

562562610630204204218245245272

272272299299340347394

442476544544

612612660680254254268295295322

322322349349390397444

492526594594

662662710730304304318345345372

372372399399440447494

542576644644

712712760780354354368395395422

422422449449490497544

592626694694

762762810830404404418445445472

472472499499540547594

642676744744

812812860880454454468505505522

522522549549590597644

692726794794

862862910910504504518545545572

572572599599640647694

742776844844

912912960960

Basal metabolic rate in children with a solid tumour.

OBJECTIVE: To study the level of and changes in basal metabolic rate (BMR) in children with a solid tumour at diagnosis and during treatment in order to provide a more accurate estimate of energy requirements for nutritional support. DESIGN: An observational study. SETTING: Tertiary care at the Centre for Paediatric Oncology, University Hospital Nijmegen. SUBJECTS: Thirteen patients were recruited from a population of patients visiting the University Hospital Nijmegen for treatment. All patients asked to participate took part in and completed the study. INTERVENTION: BMR was measured by indirect calorimetry, under stringent, standardised conditions, for 20 min and on three different occasions in all patients. Continuous breath gas analysis using a mouthpiece was performed. Weight, height and skinfold measurements were performed before each measurement. MAIN OUTCOME MEASURES: BMR was expressed as percentage of the estimated reference value, according to the Schofield formulas based on age, weight and sex, and in kJ (kcal) per kg of fat-free mass. RESULTS: At diagnosis, the BMR was higher than the estimated reference BMR in all patients and 44% of the patients were considered hypermetabolic. Mean BMR (as percentage of reference) was significantly increased (11.6% (s.d. 6.7%); P=0.001), but decreased during treatment in 12 of the 13 patients (mean decrease 12.7% (s.d. 3.9%); P