Metabolism

Half-Fast Metabolism

There is a huge amount of misinformation being taught about metabolism. This is quite understandable, as most people do not even truly understand what their metabolism is. Some folks are teaching that the rate of your metabolism determines just exactly which foods are best suited for you to eat. They teach that people are born as either fast or slow metabolizers, and glorify the advantages of being a fast metabolizer. They assert that the fast metabolizers burn through fuel more rapidly than the slow metabolizers, making the fast metabolizers relatively more efficient at digesting their food. Actually, the opposite is really true. It is easy to understand if we use a car analogy. The car that gets more miles to the gallon is more efficient than the car that gets fewer miles to the gallon. It is equally as easy to understand that the person who utilizes the least fuel to accomplish any particular task, i.e., the slow metabolizer, is the most efficient.

The fast metabolizers, it is taught, will only thrive on a high fat diet, as fruits will prove to be insufficient in terms of fuel density, leaving the consumer constantly hungry and suffering from the maladies (mistakenly) associated with the overconsumption of fruit's sugars. Only the slowest metabolizers, it is taught, could even hope to have a chance at possibly succeeding, healthwise, by utilizing fruit for fuel. Often, athletes are brought into the example. If you are a serious athlete, then you might be able to use more fruit if you are a very slow metabolizer, it is said, but otherwise, it is too easy to overeat on fruit and it really should simply be avoided.

First, let's begin with a few terms. The term metabolism represents the sum of all of the catabolic and anabolic processes that go on within your body. The anabolic activities in your body are those whereby simpler structures are united to form more complex ones. Anabolism represents the building processes in your body: growth, repair, and all of the recombinant chemistry that goes on at the cellular and visceral level. Catabolic activities are those whereby complex structures are broken down into simpler ones. Digestion, osteoclastic activity (cells that break down bones), and the conversion of glycogen to glucose are examples of catabolism in action. Metabolism is not, in and of itself, a single function, but rather a representation of the sum total of anabolism and catabolism that is going on in the body at any given time.

Physical activity, or lack of it, determines metabolic rate

The term metabolism does have a useful meaning for us, however. We use it with reference to the phrase, basal metabolic rate, or BMR. We use the two terms almost but not quite as synonyms. The basal metabolic rate is a measure of the amount of fuel a person utilizes, per unit of time, when awake and totally at rest. It does not include such functions as physical activity, daily household chores, or even digestion. When we use the word, metabolism we use it to mean BMR plus all the activities of the day. We might say, He has a fast metabolism and she has a very slow metabolism. By this we would mean that a person with a fast metabolism requires more fuel to perform the same amount of anabolic and catabolic processes as the person with a slow metabolism. This makes the fast metabolizer less efficient in their use of fuel. Either way, however, the difference is not very much, as the BMR rarely varies much more than about plus or minus 5% from person to person of similar body size and design. Body surface area, it turns out, is the biggest factor affecting BMR. BRM in humans accounts for the use of around 1000 calories per day.

What does affect fuel use is the amount of physical exertion one performs. A sedentary person may only use 200 calories per day in performing their daily functions whereas someone going for a vigorous 4-hour hike could use 2000 calories. Professional athletes often use 4000 calories solely for their daily training and Tour de France riders are known to use over 10,000 calories on certain days of this grueling competition. Hence it becomes easy to see that differences in BMR, or metabolism, as it is commonly referred to, plays an exceptionally small role in total calorie usage, usually representing less than 100 calories out of 2,000 to 4,000 or even more.

The truly fast metabolizer is one who uses more calories per hour, throughout the day, than the average person does. The more calories one utilizes in the course of the day, the faster would be their total metabolism. It can safely be said that a fit woman of average physique uses about 1800 calories per day and the average-sized fit man about 2400. Using the man for this example, it would mean that he averages about 100 calories per hour. We could therefore assert that a man who uses more than 100 calories per hour would be termed a fast metabolizer and a man who uses less than 100 calories per hour would be a slow metabolizer.

How Much Fat is Optimum?

The concept that fast metabolizers must consume more fat per calorie than slow metabolizers has been taught as fact for many years. This is contrary, however, to all we know about human health and nutrition. The Director of Nutrition for the United States Olympic Teams says, the amount of fat (as a percentage of total calories) required for the athlete remains the same, regardless of sport. The only thing that varies, sport by sport and athlete by athlete, she asserts, is the total number of calories required.