Metabolism

Helping people make CHANGES^® Metabolism

All About Metabolism...

It changes with the seasons, with age, and even with the time of day. It speeds up when we eat, and slows down when we don’t. We blame it for our excess body fat, and our fatigue. It’s called metabolism.

The word "meta" means change. Thus, metabolism is the sum total of all the changes (chemical processes) that take place within the body. It includes all of the catabolic reactions – (catabolism means breaking down) – as well as all of the anabolic reactions – (anabolism refers to building.)

Examples of catabolic reactions include:

	the breakdown of muscle glycogen into individual molecules of glucose
	the release of fat (free fatty acids) from adipose tissue
	the breakdown of muscle tissue to release amino acids

Examples of anabolic reactions include:

	the formation of glycogen from glucose
	the formation of proteins from amino acids
	the formation of storage fat from fatty acids

Basal Metabolism...

The word "basal" means base (as in baseline.) Basal metabolism is the amount of energy used to support the body's ongoing metabolic processes while the body is in a state of complete physical, digestive, and emotional rest.

It includes the energy used for:

	breathing
	maintaining body temperature
	repairing and replacement of cells and cell components
	delivery of nutrients to cells and wastes away from cells
	growth
	and heart beats.

Variations in basal metabolism..

We all know that metabolism can vary tremendously from person to person. Some of the variables include: size, height, weight, gender, body composition, activity, season, environment, growth, age, illness or injury, and nutritional status.

	The larger you are, the more Calories required to move your body through space.
	A six foot person requires more Calories for basal metabolism than a five foot person.
	A 300 pound body uses more basal energy than a 100 pound body.
	Men burn more Calories than women. (This is partly due to differences in body composition, and partly due to differences in certain hormones.)
	The more muscle mass you have the more Calories you burn. Muscle uses approximately 35 Calories per day, just for survival. Fat (a.k.a. adipose tissue) only uses 3 Calories per day.
	In cold winter weather we need more fuel for heat than in the summer. For example, the Aboriginal Eskimo is said to have burned about 7000 Calories per day just for heat production. Conversely, people who live near the equator need less fuel. (Have you ever noticed that your appetite goes down on hot summer days?)
	And children, pound for pound, need more energy than adults. (Growth uses a lot of basal energy.)
	Most of us require fewer Calories as we age. This is partly because the body becomes more efficient at doing the same tasks repeatedly, and partly because most of us become less active physically as we get older. With declining activity comes a loss of muscle tissue, which in turn means a decrease in our Caloric requirement.
	With illness or injury our metabolism increases as the body goes about the business of healing. Think, for example, about the fever that comes with a case of influenza. Or the inflamation that comes with an injured joint. From a scratch to major surgery, if you hold your hand above the part of you body that is healing you’ll feel the increase of heat pouring from the injured area. Those healing tissues are using more basal energy.
	Lastly, there’s the thyroid gland. The thyroid is a butterfly shaped gland located in the neck, and surrounding the windpipe. It produces a hormone called thyroxine which serves to regulate the rate at which metabolic reactions occur in the body. As the level of thyroxine increases so does the relative speed at which reactions occur, and so does our Caloric expenditure. As thyroxine decreases, so does the speed of metabolism. We then require fewer total Calories.

Note: For the most part the thyroid is not responsible for very large differences in body weight. Why? If your thyroid is sluggish, so is your appetite. Conversely, if the thyroid gland is overactive, so is your appetite.

There are two important factors that influence your thyroid gland - (and therefore your metabolism) - that you need to keep in mind.

	The first is stress. Chronic stress increases thyroid hormone production.
	The second is dieting. Calorie deprivation decreases production of thyroid hormone. This causes metabolism to slow down to compensate for the lack of fuel. Individuals with anorexia nervosa, for example, have a basal metabolic rate which is 50 percent below normal.

Interesting trivia: Different tissues and organs of the body also have different metabolic rates. Example: The brain and the liver – which represent only 4% of the weight of an adult – consume over 45 % of the energy used for basal metabolism.

Basal Metabolic Rate (BMR)...

... is the amount of energy required to support basal metabolism during a 24 hour period.

A Kilocalorie...

... is a large Calorie. It is a unit of energy. It is the unit of measurement that is used in nutrition to measure energy. It is actually a little bit of heat. To be exact, it is the amount of heat required to raise the temperature of one kilogram of water from 15 to 16 degrees C. (59-61 degrees F.)

You may have noticed that throughout this article I’ve spelled Calorie with a capital C. This is to differentiate it from a small calorie, the unit of measurement used in physics. A small calorie is enough energy to raise the temperature of one gram of water by one degree. If we were to estimate human energy needs using small calories the numbers would be astronomical. Example: A Fig Newton has 50,000 calories of energy, but only 50 Calories (or kilocalories.)

Thermogenesis ...

... is heat production. The term refers to the energy expended by the body to digest food and absorb nutrients.

The amount of energy needed for thermogenesis is estimated to be 10% of the total Calories needed for basal metabolism and physical activity.

How to calculate your Caloric need:

1. Multiply your body wt. by 11 (men) or 10 (women.)

2. Estimate the energy required for usual physical activity.

Less than 2 hrs walking per day = Inactive = + 30 % BMR Calories

2-4 hours of walking per day = average = + 50 % BMR Calories

More than 4 hrs walking per day = Active + 75 % BMR Calories

3. Estimate the cost of thermogenesis, and add it to your total.

Example:

100 lb. female = 100 X 10 = 1000 Calories

Add in calories for activity. In our example we are assuming the individual is inactive.

30 % of 1000 = 300 Calories

Total = 1000 + 300 = 1300

Add in allowance for thermogenesis.

10% of 1300 = 130 Calories

___________

Total: 1300 + 130 = 1430

Questions about metabolism? Contact me.
Need to know for sure how many calories you burn per day? Ask me about having a Meta-Check test.

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Note: Information presented is for educational purposes only and is not intended to substitute for a personalized consultation with a health professional.