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Dr. Lowe How to Prepare Patient-to-Patient Fibromyalgia Research Foundation
The Metabolic Treatment |
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Several people have emailed us recently asking what we think of a new device that lets you measure your own metabolic rate. It is called LifeChek™. The website for the device describes it as a "direct calorimeter." That means that it uses body heat to calculate your calorie expenditure, which is another term for metabolic rate. LifeChek™ differs from the instruments clinicians used from the late 19th century up until now to calculate a patient’s metabolic rate. The instruments clinicians use calculates the metabolic rate from how much oxygen the patient consumes. But the first devices built to calculate the metabolic rate used body heat. Lavoissier built the first one in France in the late 1700s. To calculate animals’ metabolic rates, he put them in a chamber that was sealed inside another chamber. He packed the pocket between the two chambers with ice, which was available only when it snowed. The outer chamber was insulated from the outside air. The outer insulation kept room heat from melting the ice. The ice melted only from heat an animal produced inside the inner chamber. As Goran explained, "Lavoissier measured the volume of melted ice water and by so doing was able to calculate accurately the amount of heat that had to be produced by the animal to melt the measured amount of ice."[1,pp.350-1] In the early 20th century, calorimeters that measured the heat of the whole body were in use. But they were expensive to build and operate. Also, technicians using them had trouble controlling conditions that could raise or lower a patient’s body heat, so it was hard to get measurements that truly represented a patient's heat production. As a result, few of the devices were ever built and marketed. This trouble of getting measurements that actually represent whole body heat may be an even worse problem for the LifeChek™, as I’ll explain below. Dr. Gina and I are certainly in favor of people monitoring their own health with self-use devices. Thermometers, glucometers, and blood pressure kits, for example, have been a boon to millions of people. Several factors, however, determine whether a self-use device is of practical value: (1) the device must do what the manufacturer claims it does, (2) people must use the device properly, and (3) they have to interpret the test result in a meaningful way. My initial reaction to the LifeChek™ is that it’s not useful in these ways. As a researcher, I can imagine some practical uses for the device, but I seriously doubt that people in general will use it in those ways. At minimum, I believe the device has serious limitations that customers should consider. Controlling for Factors that Can Influence the Metabolic Rate. For either the heat-based or oxygen-based test to be of most practical use, the person undergoing the test must be in a resting state. Also, he or she must have properly prepared for the test. Proper preparation involves avoiding influences that can increase the amount of heat the patient generates or the oxygen he or she consumes during the test. Preparation of the person being tested, and proper conditions during the test, are absolutely essential to getting an accurate measurement. Consider what happens when someone doesn't properly prepare for either the heat-based or oxygen-based test, or when the test isn't done under the right conditions. How much heat a person's body generates, and how much oxygen he or she consumes, can vary tremendously through the day. The variance depends on many internal and external factors. Examples are muscle contractions, emotions, processing of food, effects of stimulant chemicals, various drugs, clothing, and environmental temperature. Measuring a person's body heat or oxygen consumption when these factors are not controlled for gives a test result that is essentially meaningless. I say meaningless because we don't know the complex of factors that have interacted to raise the person's body heat or oxygen consumption above a resting level. For example, a woman may sit down at home to use the LifeChek™ to see what her metabolic rate is at 3 PM. Is the measurement the device gives her influenced by the time of day? Is it influenced by her having just finished rearranging heavy boxes in the garage? By her sitting in a position that makes her neck muscles contract? By her keeping her ears alert for sounds of the delivery man she doesn’t want to miss? By the metabolism-driving protein lunch she had at noon? By her husband oddly not having phoned her to let her know his plane flight was safe? By the sedating wine she drank an hour before? What were the metabolism-influencing factors that influenced the measurement she got? To what extent did they interact to influence the test result? We simply can't know. Clearly, to make sense of a metabolic rate test, we must properly prepare and properly conduct the test. In view of this, consider this statement at the LifeChek™ website:". . . LifeChek™ measures your metabolism - the calories you burn - at any given time. LifeChek™, worn discreetly, reads calories burned every 12 seconds, records the information and makes it available to you. And, you don't have to be active when measuring your calorie burn rate. You can measure when resting, watching television or even when you're eating."[2] Dr. Gina and I follow strictly proper protocol in our clinic to ensure that we can accurately interpret the result of a patient’s metabolic test. To do so, as I said above, the patient must prepare in a particular way and go through the test under strictly controlled conditions. The LifeChek™ website indicates that you can use the device with no consideration of proper test protocol. Because of that, I have no idea how anyone could ever interpret its results meaningfully. Variations in Skin Temperature. I have another doubt about the usefulness of the device. Judging from the pictures on the LifeChek™ website, the person straps the device onto an upper arm. The device then measures the temperature of that particular body part. By contrast, the traditional method of calculating the metabolic rate from body heat uses a chamber akin to a full-body tanning booth. The patient lies in the chamber, and, when he or she reaches a true resting state, sensors measure the heat that the whole body emits. Someone then applies an equation that uses the patient's resting whole body heat to calculate the resting metabolic rate. In using this method, we can accurately calculate a patient’s whole-body metabolic rate only when we know for sure his or her whole-body temperature. We can use the heat of a particular body part to infer the heat of the whole body. But for the calculation of the metabolic rate to be accurate, the heat of that body part must be the same as that of the whole body. Otherwise, we’ll inaccurately calculate the patient’s whole-body metabolic rate. The reason that measuring heat at only one body part may give an incorrectly calculated metabolic rate is that skin heat can vary markedly at different body sites. This is especially true of the skin of the arms. There are several reasons for this. For example, one upper arm may have more arteries coursing through it than the other. Arterial blood is warm. Because of this, the arm with the more prolific arterial tree will have a higher skin temperature than the other. As a result, the metabolic rate calculated from one arm may be different from that calculated from the other arm. Even if the skin heat of each arm is the same, many people have troublesome body parts that can alter the temperature of the arms. Examples of such problems are muscles that are severely tense, pain-generating trigger points, thoracic outlet syndrome, and vertebral subluxations and other problems with the spine in the neck. Noxious sensory nerve signals from these problem areas flood the spinal cord in the neck. Inside the spinal cord, the signals set off an excess of sympathetic nerve signals. These signals then pass from the spinal cord to the arteries in the skin of the arms. In response, the arteries constrict and transport less warm blood through the skin. The skin then cools. If the person uses LifeChek™ on this cooled skin, the heat it measures will be lower than the person's actual full-body heat. The device will then calculate the person’s whole-body metabolic rate as lower than it actually is. That such factors can alter skin heat in the arms leaves me with a question: Can the LifeChek™ accurately calculate the overall metabolic rate from a small skin measurement? That many factors can interact at once to raise body heat to different levels causes me to ask another question: Without proper preparation and controlled testing conditions, will one ever know exactly what produced the heat the LifeChek™ measured? The marketers of the device may consider my questions mere quibbles. As a metabolism researcher, however, I think the questions are important ones to ask. Nonetheless, anyone curious about the device can read about it at the following website: http://www.lifechek.com/medical.html. Reference
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