Basal Metabolic Rate Calculator
Understand your typical estimated caloric burn rate based on your age, weight, height, gender, and the amount of exercise you get. This calculator returns your average calories burned per hour & per day.
Basal Metabolic Rate
BMR & RMR and What They Mean
The BMR (Basal Metabolic Rate) & RMR (Resting Metabolic Rate) are estimations of the number of calories an individual will burn when he or she does nothing but rest for an entire 24 hours.
The BMR & RMR represent the least amount of energy that is necessary to maintain body functions. Some of these functions include the continual beating of the heart, breathing and keeping the body’s temperature within the appropriate range.
BMR is the same as your BEE (Basal Energy Expenditure). Your BMR Measurement is generally taken immediately after wakening from an eight-hour sleep session in a dark room. The individual is required to fast for 12 hours to make sure that the digestive system is not active and the individual must rest in the reclining position.
RMR is identical to the REE (Resting Energy Expenditure) these measurements are usually taken with fewer restrictions than the BMR and the individual is not required to sleep in a test facility before the testing procedure.
The majority of people that search the internet for information about their metabolic rate will usually search for the term BMR because it is so frequently used. Actually, RMR is many times more suitable for an individual’s needs and is generally a more accurate estimate.
If an individual is trying to find information concerning the number of calories that they personally need to burn daily, it is best not to use his BMR or RMR. It is best to calculate the amount of activities that the individual performs in a 24-hour period as is described when calculating the necessary calorie needs per day.
There are several things that will decrease your RMR & BMR
- It decreases with weight loss.
- It will decrease with age.
- It also decreases as you become shorter with aging.
As an individual grows older, shorter and loses weight, his RMR & BMR will decrease and he will have to exercise more frequently or eat less to maintain his current weight.
The Calculations
Because the RMR & BMR merely represent an individual’s resting expenditure of energy, adjustments need to be made to reflect his level of activity. This is accomplished by multiplying his RMR or BMR by a factor of an activity.
The activity factors below also acknowledge the food’s thermic effect:
- If an individual performs non-strenuous exercise one to three days weekly, he is considered lightly active. His activity factor would be 1.375.
- A desk job with little or no exercise will have an activity factor of 1.2. This factor is considered sedentary.
- A moderately active individual exercises moderately three to five days weekly. His activity factor would be 1.55.
- An individual is considered extremely active if he performs strenuous exercises daily and has a physically demanding job. His activity factor would be 1.9.
- A very active individual is someone who performs hard exercise six to seven days weekly. His activity factor would be 1.725.
Using these activity factors will produce a rough estimate. There is a multitude of various opinions concerning these activity factors. Therefore, it is suggested that the actual activities performed should be used for calculating the amount of calories that were actually burned during the period being calculated.
Consequently, when someone calculates the number of calories that need to be burned in a day, the BMR or RMR are not added into that equation.
RMR & BMR Equations
There have been equations developed for estimating the RMR & BMR when testing is impractical. The Harris-Benedict equation is used for the BMR and for the RMR, the Mifflin equation is used.
The Harris-Benedict Equation is Somewhat Inaccurate
The Harris-Benedict equation is the standard and has been used for decades. It is still used most often for the estimation of BMR. However, some studies suggest that it is somewhat inaccurate for several reasons:
- According to the test standards set today, the Harris-Benedict equation actually estimates RMR, not BMR. The main reason this has been suggested is that the individuals tested did not stay the night at a test facility.
- The Harris-Benedict equation was developed using individuals that did not offer an ample representation of people who are considered obese. Older and younger individuals were not adequately represented either. The misrepresentation of these individuals is becoming more and more significant as our populations continue to become heavier and older. While all of the equations that predict energy expenditure are only estimates, this equation generally overestimates by at least five percent.
The Mifflin Equation is Considered the Most Accurate
In 1919, the Harris-Benedict equation was published and several studies have tried to improve it. The most accurate results produced are from the Mifflin equation that is used in the calculation of RMR.
The Harris-Benedict Equation to Obtain BMR:
For women: (9.56 x w) + (1.85 c h) - (4.68 x a) + 655
For men: (13.75 x w) + (5 x h) - (6.76 x a) + 66
The Mifflin Equation to Obtain RMR:
For women: (10 x w) + (6.25 x h) - (5 x a) - 161
For men: (10 x w) + (6.25 x h) - (5 x a) + 5
(w) Equals your weight in kilograms
(h) Equals your height in centimeters
(a) Equals your age
To determine your weight in kilograms divide your weight in pounds by 2.2.
To determine your height in centimeters multiply your height in inches by 2.54.
To determine your daily calorie needs you need to multiply your RMR by your ‘activity factor.’
Sedentary = 1.2
Slightly Active = 1.375
Moderately Active = 1.55
Very Active = 1.725
Extra Active = 1.9
Body Composition
The measure of the fat and muscle percentages (body composition) is not taken into account in these equations. This means that the equation is less accurate if you do not have a typical amount of muscle. The reason for the inaccuracy is that muscle will burn calories, while fat will not.
A person that has above average muscle mass will have an RMR or BMR that is higher than calculated, whereas a person that has muscle mass that is less than average will have an RMR or BMR that is less than calculated.
Slow Metabolism and Weight Gain
Women have a tendency to blame the inability to lose their added weight on a slow metabolism. Researcher James Hill, Ph.D., who is the director at the Center for Human Nutrition at the University of Colorado Health Services Center in Denver, states that the belief that a slow metabolic rate is usually the culprit when excess weight will not come off is one of the misconceptions concerning metabolism. He states that even if your metabolism is slower than what is considered typical you are not destined to be obese or overweight.
The subject of metabolism is somewhat confusing. There are some common myths that suggest certain things can increase your RMR and drop the extra weight.
What determines how high or low your metabolism is?
The composition of your body is the main factor used to determine your RMR. Hill states that an individual’s resting metabolic rate (RMR) is controlled by the amount of fat-free mass he has. This fat-free mass includes bones, lean muscles and organs, etc. The more fat-free mass he has the higher his RMR will be. That is why an average man’s metabolism will be ten to twenty percent higher than an average woman's will.
A plus-sized woman’s RMR could be as much as fifty percent higher than the RMR of a woman that is thin. This is because the plus-size woman has a total body mass that is significantly greater than the thin woman’s is. In fact, hormones and heredity are some of the other factors that help to dictate an individual’s metabolism. Some of these factors include:
- Thyroid problems, such as hypothyroidism, will affect your metabolism.
- Insulin resistance is when the body has difficulty processing glucose. This causes high levels of glucose to be in your system, which in turn, causes your body to store fat.
- Dropping your caloric intake too quickly can cause your body to enter into a ‘starvation’ mode causing it to store fat.
- Medications can sometimes cause insulin resistance, which then causes your body to store fat.
- Stress can raise your cortisol levels, which will cause your body to store fat.
All these factors affect your metabolism because they increase the fat in your body. High fat mass means your RMR is lower.
Studies have shown that our baseline metabolism is actually determined when we are born. However, having a naturally slow metabolism does not mean that weight gain is inevitable. Even though losing those extra pounds will be harder for those with a naturally slow metabolism, it is usually possible, according to weight-loss expert Pamela Peeke, MD., M.P.H. She states that with a slow metabolism, it will be more difficult to burn calories rapidly, but by building lean muscle and exercising, you do have the ability to raise your RMR, somewhat.
Weight Gain with Aging
Many people could eat anything they wanted in their younger years, and now find themselves having to watch their diet more closely. This is because; once a woman turns 30 years old, her RMR begins decreasing by two to three percent every ten years. Generally, this decrease is due to the lack of exercise causing muscle loss. Hill states that some of that loss can be reversed or even prevented with an active lifestyle and regular exercise.
Yo-Yo Diets
Many people believe that ‘yo-yo’ dieting will do permanent damage to their metabolism. Hill states that there will be a temporary drop in your RMR, five to ten percent, whenever your calories are significantly reduced to drop excess weight. However, there is no definite evidence showing this kind of dieting causes permanent damage to your metabolism.
Workouts to Raise Your Metabolism
The experts agree weight training is more effective in building and preserving lean muscle than other exercise methods. Even so, the majority of them also feel that lean muscle influence on metabolism is very slight. Researcher Gary Foster, Ph.D., who is an associate professor at the University of Pennsylvania School of Medicine, has stated that every pound of lean muscle can actually raise the RMR as much as 15 calories daily.
When it comes to cardio, a workout that is high in intensity and really raises the heart rate will provide you with the highest short-term boost to your metabolism and burn the most calories. This happens because the workout raises your metabolism from 20% to 30%, depending on the workout’s intensity level. However, it will not affect your RMR permanently. Once you have completed your workout, over the next few hours your metabolism returns to its level when resting. You will continue to burn extra calories over those few hours though, prior to returning to your RMR.
Nutrients & Your Metabolism
The majority of the data collected shows that your food choices have no significant impact on your RMR. Fats, carbohydrates and proteins seem to have similar affects on metabolism. There is a temporary increase in metabolism from protein, but it is rather insignificant.
What does make a difference is the amount you eat. Your metabolism will decrease if you lower your caloric intake below what is necessary to maintain your basic functions, this is how your body conserves energy when food is unavailable or in short supply.
The more you cut your calories, the lower your RMR will fall. For instance, a very low-calorie diet with less than 800 calories daily, may cause your rate to fall more than ten percent. This slower metabolism will probably occur within 48 hours of the start of your diet. To keep your metabolism from dropping excessively, you should reduce your calories in a moderate and healthy way. For a safe, lasting loss of weight, an average woman should not eat less than 1,200 calories daily.
Spicy Foods and Your Metabolism
Spicy foods can boost your metabolism, but not to affect your weight loss. In fact, anything that raises the temperature of your body will raise the rate of your metabolism temporarily. However, the increase with consumption of spicy food is minute and short-lived so it does not have any impact on weight loss.
Metabolism Rates & Weight Loss
Your RMR will actually slow down as you lose your excess weight because there is less body mass to be supported. Your body will then need fewer calories to maintain your vital functions. Consequently, you will not need to consume as much to feel content and fuel your exercise. If you do not modify your exercise and eating habits, you will ultimately reach a plateau in your weight loss. To move past this plateau and continue to lose your excess weight, you will need to consume fewer calories, remember not to drop too low or you can just increase the duration or intensity of your workouts.
Products Promising to Elevate Your Metabolism
At this time, there is no patch, potion or pill that can magically increase your metabolism enough to assist you in losing weight. If you are looking for a quick boost in your metabolism, you should go for a brisk walk or head to the gym for a good workout.
Certain Medications can Slow Your Metabolism
There are medications that will lower your metabolism. Some of the common drugs that cause this problem are the medications used to treat bipolar disorder and depression. If you are prescribed a medication that will cause you to gain weight, ask your physician if he knows of an alternative medication that is not likely to cause weight gain.
How to Lose One Pound of Body Fat a Week
In order to lose one pound of body fat weekly, you would need a deficit of 500 calories daily. The best way to accomplish this and avoid an excessive drop in your metabolism is with the use of diet and exercise concurrently. A good example is eliminating 250 calories from your daily caloric intake and also burning 250 calories with exercise.
Your Metabolism Converts Food into Energy
Metabolism is your body’s process of converting what you drink and eat into energy. This biochemical process is complex. The calories in the beverages and food are combined with the oxygen in your body to release the energy that is necessary for your body to function. Even while you rest, energy is needed for all the basic functions in your body such as, repairing and growing cells, circulating your blood, breathing and adjusting your hormone levels.
The energy needed to maintain the basic functions of your body are fairly consistent and do not change easily. Your BMR accounts for nearly 60% to 75% of the calories that are burned daily.
Besides your BMR, there are two other factors that determine the number of calories you burn daily:
- Processing of the food you consume (thermogenesis). This refers to the digestion, absorption, transportation and storing of the food that has been consumed. These processes account for nearly 10% of the calories used daily. The energy your body needs to process food is usually steady, and does not change very easily.
- Exercise and physical activity account for the remainder of the calories that your body will burn daily. Some of these activities include, walking your dog, playing sports or any other movement.
There are very few medical conditions (hypothyroidism or Cushing’s syndrome) that can cause excessive weight gain by slowing down metabolism.
Weight gain is generally caused by eating more calories than your body burns. Therefore, to lose your excess weight, you will need to create an energy shortage by eating less and increasing your activity to burn more calories.
Healthy Way to Reduce Your Caloric Intake
If you are interested in losing fat, the guideline for reducing your caloric intake is reducing your daily calories by no less than 500, but no more than 1,000 below your necessary level for maintaining your body. For those that only need to lose a little bit of weight, 1,000 calories is above what is necessary to cut. If we use the American College of Sports Medicine’s guide to the recommended minimum intake of daily calories, their guide recommends that daily caloric intake never fall below 1,200 calories for a woman or 1,800 calories for a man. Even these caloric intake levels are considered rather low.
Another way to determine a minimum daily calorie level that is safe is by referencing your current weight. A good place to start is by reducing your daily caloric intake by 15% to 20% below what your maintenance needs are. This percentage can be increased according to the amount of weight you wish to lose.
Physical Activity & Metabolism
We do not have very much control over how fast our metabolism is, however, we can control the number of calories burnt by our activity level. We burn more calories when we are physically active. Some individuals who are considered to have fast metabolisms are most likely just more active.
It is important to remember that any added movement throughout your day will help you burn calories. Try to find ways to move around and walk several extra minutes daily. Park farther away from the store entrance, taking the stairs instead of the elevator, wash your car, gardening and even housework can assist in burning the extra calories needed and help you with your weight loss.
Supplements
Products claiming to raise your metabolism are many times more propaganda and could cause some undesirable and sometimes dangerous side effects. The manufacturers of dietary supplements are not required to prove their products safety or effectiveness to the Food & Drug Administration. For this reason, you should be skeptical and cautious about these various supplements. Also, always inform your physician about all the supplements you take.
The answer to healthy and long-term weight loss is diet and exercise. If you have difficulty dropping excess weight even with proper exercise and diet, talk with your physician.
Thermogenesis & BMR
Our bodies generate heat. This process is called thermogenesis. To determine how much energy we have used, our thermogenesis is measured. The majority of individuals do not maintain much lean body mass as they age. Because of this, our BMR generally decreases as we age.
Some things that can affect our BMR include, environmental temperatures, food and beverages that have been consumed, stress levels and illness can all affect our overall energy use and our BMR.
The Process of Measuring the BMR & RMR
There are extremely restrictive circumstances necessary to measure an individual’s BMR. To obtain an accurate measurement, the individual’s sympathetic nervous system must not have any stimulation; this requires the individual to be completely at rest.
A measurement that is closely related to the BMR, but does not require such strict conditions is RMR.
Gas analysis, through indirect or direct calorimetry, is used to measure RMR and BMR. However, an equation using weight, height, sex and age can provide a rough estimation of an individual’s RMR and/or BMR. The R.Q. (respiratory quotient) is used to measure the intrinsic composition, as well as, how the fats, proteins and carbohydrates are converted into energy substrate units. Our bodies then use these units as energy.
Studies that were conducted in 1990 by Spennewyn discovered a strong correlation between metabolism and lean mass. Spennewyn realized that the lean tissue in women and men required about 16 calories a pound each day. Therefore, after lean mass had been determined, it could then be multiplied by 16 to find the individual’s daily caloric needs according to their activity level. This method is frequently used in health clubs when determining an individual’s daily caloric needs.
Dietary Considerations & Nutrition
Basal metabolism is generally the largest part of an individual’s total calorific expenditure. The equations developed by Harris & Benedict are just approximate. The variations in BMR, energy expenditure in thermogenesis and the physical activity levels make it hard to make an estimate concerning the dietary consumption that any particular person needs to maintain his body weight.
Hypothalamus & Your Metabolism
The main organ that is responsible for managing your metabolism is your hypothalamus. It is located in the posterior section of your forebrain (diencephalon). The hypothalamus forms part of the sidewalls and floor of the cerebrum’s third ventricle. The principal functions of your hypothalamus are:
- It controls and integrates activities of your ANS (autonomic nervous system).
- Your ANS regulates your cardiac muscle and smooth muscle contractions.
- Through your ANS, your hypothalamus regulates your visceral activities, such as moving food through your stomach and intestine, controlling your heart rate, regulating your body temperature and the contractions of your urinary bladder.
- Your hypothalamus, through your ANS, also produces and regulates your feelings of aggression and rage.
- Your ANS also regulates the secretions of various endocrine organs including your thyroid gland, which is linked to a multitude of metabolic disorders.
There are two centers that are responsible for regulating our food intake. Our hunger center or feeding center is the area that causes our hunger sensations. When adequate amounts of food or substrates have been consumed and your leptin (a hormone that is thought to suppress our appetite) is high, our satiety center gets stimulated and then sends impulses to inhibit our feeding center.
When there is not a sufficient food supply in our stomach and our ghrelin (a hormone that stimulates our appetite) levels are elevated, receptors in our hypothalamus cause us to feel hungry.
Our thirst center is very similar because when particular cells within our hypothalamus are stimulated by a rising osmotic pressure of extra cellular fluid, we become thirsty. If we satisfy our thirst, our osmotic pressure will decrease.
All these functions together create our survival mechanism that makes us sustain the processes in our body that RMR and BMR measure.
Calories
To be specific, a calorie is how much heat or energy it will take to increase the temperature of one gram of water 1°C (1.8° F). In fact, 4.184 joules, which is the usual unit of energy that is used, equals one calorie.
Many of us are not sure exactly what a calorie actually means or is. We usually associate food with calories; however, calories apply to all things that contain energy. For instance, four liters (a gallon) of gas has approximately 31,000,000 calories!
We think things like a particular can of pop has 140 calories, whereas the diet can of pop only has two calories. The calories listed on the packages of things we actually consume are kilocalories and 1,000 calories is equal to one kilocalorie. A ‘food’ calorie has 4,184 joules. Therefore, a can of pop that has 140 food calories contains 140,000 regular calories or 140 kilocalories. This means that the gallon of gas has 31,000 kilocalories.
The same rule applies to exercise. When you look at a fitness chart and it shows that you burn approximately 100 calories for each mile you jog, it means 100 kilocalories. When calories are referred to in the rest of this article, we are actually talking about a kilocalorie.
What Does a Calorie Do?
Caloric Breakdown:
- One gram of carbohydrates equals four calories.
- One gram of fat equals nine calories.
- One gram of protein equals four calories.
Humans need energy to live. This energy is used to move, breathe and pump blood through our bodies. All these actions acquire their energy from our consumption of food.
The amount of calories that are in a particular kind of food is equal to the amount of possible energy possessed by that food. If you know how much fat, carbohydrates and proteins are in a particular kind of food, you can determine the number of calories or potential energy that food will supply.
The nutritional label located on the back of a container of oatmeal shows that half a cup of dry (40 g) oatmeal has 155 calories. That means that if we poured this amount of oatmeal in a dish, caught it on fire and burned it completely, this reaction would produce 155 kilocalories.
This is enough energy to increase the 155 kilograms of water’s temperature by 1°C (1.8° F). Taking a closer look at the label it shows that this amount of oatmeal contains three grams of fat, 27 grams of carbohydrates and five grams of protein. This produces a total of 155 kilocalories. Remember the equations to use to determine the amount of kilocalories: fat equals nine kilocalories, carbohydrates equal four kilocalories and protein equals four kilocalories. Here are the equations used to determine our oatmeal’s calories.
- Fat (9 kilocalories x 3 grams) 27 kilocalories
- Protein (4 kilocalories x 5 grams) 20 kilocalories
- Carbohydrates (4 kilocalories x 27 grams) 108 kilocalories
- Grand Total of 155 kilocalories
Our bodies will burn these calories through our metabolic processes. During this metabolic process, enzymes breakdown the proteins and fatty acids into amino acids. The carbohydrates are broken down into glucose or other sugars and fats into glycerol.
These molecules will then be transported through our bloodstream to our cells.
Fat, Exercise & Calories
If you consume more calories than you do burn, you will gain weight. If you consume fewer calories than you burn, you will lose weight. Once you accumulate 3,500 unnecessary calories, your body stores these as one pound of fat.
Your body stores fat to use as energy at another time when it is needed. On the other hand, if you use 3,500 more calories than what you consume, whether by eating less or exercising more, your body will convert one pound of your previously stored fat to use for energy.
Exercising raises the rate of your metabolism. This increase occurs while you are exercising and for approximately two hours afterward.
Does it Matter Where Our Calories Come From?
If we are only talking about weight & you are actively burning off most of what you eath, thenit is irrelevant. A calorie from protein is the same as a calorie from fat. These calories are just units of energy. If you burn exactly the amount of calories you consume, you will remain at the same weight. If you burn more, you will lose weight if less, you will gain.
However, if we are talking about nutrition, it does matter where those calories come from. Calories from proteins & complex carbohydrates are healthier than those from simple carbohydrates & fat calories. It is necessary for our bodies to have a particular amount of fat to ensure it functions properly. Some fat is necessary to allow our bodies to absorb vitamins.
How Stuff Works has a number of articles about how calories work.
The U.S. Food & Drug Administration (FDA) recommends that no more than 30% of the calories we consume daily be from fat. Therefore, if you consume 2,000 calories daily, the maximum amount of fat allowable is 67 grams, which equals 600 calories. Many nutritionists and physicians have decreased the number recommended by the FDA to 25%. That is 56 grams, which is equal to 504 calories of fat daily for the 2,000-calorie diet.
Below we will look at some of the fat and calorie content of some common household foods.
- One cup of chocolate syrup has 837 calories and 3 grams of fat.
- One cup of canola oil has 1,674 calories and 218 grams of fat.
- One cup of cheddar cheese has 531 calories and 44 grams of fat.
- One cup of peanut butter has 1,520 calories and 129 grams of fat.
- One cup of granola has 270 calories and 8 grams of fat.
- One cup of sugar has 774 calories and 0 grams of fat.
- One 12 FL OZ (355 mL) can of Coca-Cola has 140 calories and 0 grams of fat.
However, some diets are so aggressive at cutting out fat that they end up loading diets full of sugar, which can lead to insulin resistance, metabolic syndrome, weight gain, increased risk of a heart attack & a whole slew of other health issues.
While some candies may proclaim to be "a fat free food" on the packaging, if they consist mostly of sugar & high fructose corn syrup they are likely far worse for you than most high-fat foods. Some energy drinks are similarly loaded with sugar (or high fructose corn syrup). A good movie about this problem is Fat Head. Tom Naughton has interviewed doctors who recommend having more fat & less carbohyrates in your diet than what the FDA suggests:
We know for a fact that wheat consumption has been unhealthy for humans for as long as we’ve consumed it from observations such as those pointed out by Dr. Diamond: humans being shorter, fatter, and sicker (bone disease, dental decay, cancer, perhaps atherosclerosis) with wheat consumption, as well as descriptions of the ravages of celiac disease as long ago as 100 AD.
It’s the changes introduced by geneticists over the past 40-50 years, coupled with dietary advice to consume more wheat, that have conspired to create this current mess we are in, turning wheat from a problem ingredient into a health scourge exerting adverse health effects on an international scale. - Dr. William Davis
The below YouTube video from Robert H. Lustig, MD, UCSF Professor of Pediatrics in the Division of Endocrinology, is one of the best pieces of dietary advice you will ever come across.
