Your Metabolic Rate


Basal Metabolic Rate is defined as the amount of calories burned while at rest to maintain function of vital organs such as the lungs, brain and heart. It is also the largest factor of total caloric expenditure. Simply put, it is the minimum amount of calories needed in a day to avoid the depletion of sugars, fat and muscle in the body.

If you eat fewer calories, the body senses starvation and begins to decrease metabolic activity. Your body starts to think you are trying to kill it. Therefore, it begins slowing down in order to delay death as long as possible.

Active Metabolic Rate is the number of calories burned off in a day from the activity your body performed. This number is largely determined by what you do the majority of time in your day.

Usually, an office worker will burn fewer calories in a day than a construction laborer. However, what if the office worker was training for a triathlon? During spare time, he or she may spend three hours a day doing a combination of swimming, biking and running. Who would burn more calories now? Does eight to ten hours of physical labour outweigh the triathlete who sits all day at a desk but trains all night?

These questions lead to the variables affecting your metabolic rate.

The amount of calories eaten in a day is used up in three main ways: Sixty percent of the calories are used up for your basal metabolic functions, as described above. Thirty percent of daily calories are burned up by the type, intensity and duration of physical activity you do. Ten percent of calories consumed are used up thermogenically. If you eat a food that is 100 calories, six to ten percent of those calories will be used up ingesting, absorbing and eliminating the food. Proteins tend to have a higher thermogenic effect than carbohydrates and fats.

You can get a more direct measurement of metabolic rate from a metabolic cart. Some university or medical clinics that specialize in health audits offer this service. During the examination, the administrator will have you lie down and place an oxygen exchange mask over your face. The machine then measures your oxygen and the carbon dioxide you expel. Research shows a link between breathing and calories expended at rest.

An option for an indirect measurement of metabolism is to use a metabolic equation. This equation uses weight, height and age to estimate how many calories needed in a day. The following equation was developed in 1990:

BMR = (9.99 x weight in kg) + (6.25 x height in cm) – (4.92 x age)
For men add 166, for women subtract 161

The result of this equation is the number of calories needed in a day if no activity or exercise was performed. Your AMR (active metabolic rate) is the amount of calories needed to maintain your weight, including any daily activity and exercise you perform. The more active you keep your body, the more calories you can eat without fear of gaining weight. The following categories include a number you multiply your BMR with to determine your AMR.

Sedentary (1.05)
Work involves sitting at a desk all day long. You drive from your garage to a parkade and take the elevator to your office. At home, you watch TV or work on the computer until you go to bed.

Lightly Active (1.2)
Work involves sitting at a desk most of the day. You walk approximately 30 minutes in a day, sometimes taking the stairs instead of an elevator. At home, you clean the house or do some gardening.

Active (1.4)
Work involves a small portion of the day at a desk, though most of the day you are moving. You tend to exercise for about an hour every day.

Very Active (1.6)
You only sit down during the day to eat. You exercise up to two hours per day.

Super Active (1.8)
Work involves continual hard labour throughout the day. As a recreational athlete, you still find time to exercise up to two hours per day.

Pro Athlete (2.0)
Your job is to train your body to compete at a high level of athletics. Exercise, nutrition and recovery is all you think about.

There are many factors that have an affect on metabolic rate. Below are eight significant causes important to know. Your control of these variables can ultimately lead you into maintaining a healthy weight throughout your life.

1. Genetics

Even though you can not control your genetic makeup, it is important to never use it is as an excuse to justify obesity. Yes, some people have an easier time staying leaner than others. They can eat more food, or higher calorie food and not gain as much body fat as people with a slower metabolism. Sometimes, it is easy identifying higher metabolic types by the way they move. There is a bounce in their step, or their body movements are quick, even jittery.

Slower metabolic individuals tend to move more sluggishly. Imagine over the course of a day, week, or year, the difference in caloric expenditure between these two types of metabolism. I guess never being able to sit still has its advantages! However, the slower metabolic types may be more stress free, and might live longer!

2. Age

Research shows that metabolism will drop about two percent every decade of life. This means that if you are allowed 2000 calories per day when you are thirty, you can only eat 1960 calories when you are forty.

The difference may not seem that huge but, over the course of a year, 40 calories per day adds up to four pounds per year. At the end of ten years you will have gained 40 lbs! This explains why many people do not understand how extra weight was gained.

3. Muscle to Fat Ratio

A healthy body fat percentage is an indicator of healthy adult weight than any scale. A scale does not differentiate between fat and muscle.

Most fitness experts say that a healthy range for men is between fifteen to nineteen percent. A lean body composition would be between ten to fourteen percent. Because of increased estrogen levels and a lower amount of total muscle mass than men, a woman’s healthy body fat level can be higher, ranging from twenty to twenty-four percent.

An athletic body composition would be between fifteen to nineteen percent. The average North American has a body fat percentage in the mid-thirties. Muscle is a metabolically active tissue. It takes more calories to maintain cellular activity in muscle. Most researchers suggest between 30 to 40 calories are burned per pound of muscle each day.

A highly active male can add about five to eight pounds of muscle in a year of intense training. This means he can eat somewhere between 150 to 300 calories extra per day and without worrying about storing the calories as fat.

4. Excess Post Oxygen Consumption (EPOC)

When your body heats up during intense exercise, it is like turning on your oven. When you are done, the oven does not cool off right away. It takes time.

If you ever played an intense game of squash or had a powerful spin class, then had to shower and go back to work, you may have noticed after showering, you were still sweating. This is EPOC.

After exercise, your body burns calories at an accelerated rate. Cellular activity is higher, making the adjustments you wanted your body to achieve during the workout. The amount of calories you expend post-workout depends on the intensity and type of exercise you performed. The amount of time you spend near your maximum heart rate is the major factor affecting EPOC.

In my opinion, the best way to achieve a high EPOC is to use large muscle groups such as the legs and gluteus, multi-joint movement patterns, heavy free weight loaded exercises and little to no rest between movements.

EPOC is only a temporary metabolic boost. Within an hour of post-exercise, the majority of extra calorie burning benefits are over. Some research states that EPOC can extend up to eight hours. However, after the first hour, the extra caloric expenditure is minimal.

One reason overweight, sedentary individuals have trouble initially losing weight is that they cannot tolerate high-intensity exercise. Though their heart rates can quickly increase in a workout, they can not tolerate these higher heart rates because they’re so de-conditioned. Sticking to an exercise program, eating healthy and becoming fit are crucial in increasing metabolic rate.

5. Eating Every Three Hours

Regularly consuming high-nutrient foods can prevent your metabolism from dropping and even temporarily increase your metabolic rate. If you go without food too long, your body will use up stored energy and begin to lower its metabolic activity in case there is a period of starvation. The body protects itself by slowing down all cellular activity to save stored energy and fat.

Most dietitians recommend nibbling on small meals every three hours, or five to six times per day. Each meal should be a healthy choice of complex carbs, protein and fat. I find the best percentage of each to be a 50/30/20 split of total calorie intake. Too many carbohydrates at one time or a long delay between meals can create an insulin spike. In order to remove sugar from the blood stream, the pancreas secretes insulin. The problem is that too much insulin can promote fat storage; another protective mechanism in case of a starvation state.

6. Proper Nutrition

Many foods contain tons of nutrients that the human body needs. Nutrients ensure that the cells and chemical reactions within our bodies occur effectively.

There are trillions of cells in the human body. Every day, cells die and new ones develop. Within a six month time period, all cells that existed are replaced with new ones.

The question is, do you want your new body to be made up of French fries, cola and doughnuts, or fresh fruits, vegetables and lean meat?

7. Pills

There are many products on the market sold to boost metabolism. Ephedrine is a chemical derivative of the herb ephedra, which stimulates the central nervous system, increases heart rate and causes the lung bronchi to dilate.

Usually combined with caffeine, ephedrine has become a popular marketing tool for weight-loss and boosting energy levels. These pills increase metabolic rate temporarily while they are circulating in the body. Once the product is no longer taken, the metabolic rate drops. This affects the hormones that regulate the body. The body stops producing these hormones when metabolic enhancers enter the system causing an imbalance.

Health Canada issued a warning to Canadians not to use products containing ephedrine with caffeine. Sixty adverse affects have been reported in Canada with the use of these products, one directly related to death. The adverse affects of using ephedrine are dizziness, headache, anxiety, nervousness, irregular heartbeat, hypertension, seizures, stroke, even death.

8. Fitness Level

Being in great shape is probably the main factor in maintaining a higher metabolic rate. The body has to burn many calories in order to support highly functioning cardiovascular, muscular and hormonal systems.

If you are physically fit, you will be able to accomplish so much more in the same amount of time than an unhealthy person. Some elite athletes are able to burn up to 1500 calories during a one hour workout session. An inactive individual just starting out will most likely only be able to burn one-third of that amount.

Another benefit to being fit is the amount of calories you expend during non-workout hours of the day. Someone with a lean body burns more calories all day long, even while asleep. It is no wonder those who are in shape can often eat much more than others and not gain weight.

I always tell people not to worry about what the scale says. Focus on clean eating and getting fit. Train for something. Play sports, or meet friends for a walk/run instead of dinner and drinks. Force your body to do something it has never done before. Get fit and the fat will take care of itself.

1 reply
  1. Karen Peterson says:

    Thank you so much for this, Paul. I have been craving this education. Now I feel like I have a guide to refer to and make intellegent choices for my diet and for my work outs. I knew the read outs on the cardio machines at my gym couldn’t be right if they are the same for everyone. And the treadmill keeps counting calories burned even if I’m not on the thing! I love the workouts you suggest on your site and in the Bodcast. I just wish the Edmonton winter didn’t last so long, cycling is my favorite sport. Love to be OUTSIDE!

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