Overview of Metabolism

Are you experiencing fatigue, confusion, hyperventilation, irregular heartbeat, sharp blood sugar fluctuations, or unexplained weight loss or gain? If so, you may have a metabolic imbalance.


The chemical reactions that energize all the physiological processes within our bodies are collectively known as our metabolism. By converting the nutrients from food into energy that our cells can store and use, our metabolism maintains the body during rest and boosts energy availability when it is active. It is a finely tuned system that can regulate itself, sensing the byproducts of fats, proteins, and carbohydrates that are broken down. Metabolism is also controlled in part by hormonal cues and other cell signals that indicate physiological activities throughout the body that might require more (or less) energy.

Metabolic processes can be divided into two parts: catabolism and anabolism. Catabolism pathways chemically break down the larger molecules of the nutrients we ingest into forms that our bodies can use more directly. Proteins are broken into amino acids, lipids into fatty acids, and carbohydrates into monosaccharides (such as glucose). All of these chemical reactions also release energy which can be used by the next part of the process, anabolism. During anabolic processes, all those catabolic breakdown products are used to construct new molecules for the body to use in its cellular functions. Anabolism, like catabolism, is controlled in part by hormonal cues.

It is the balance between catabolism and anabolism that defines how much energy the body stores and how much food it needs. The rate with which the body uses the stored energy is referred to as the metabolic rate. The higher the body’s metabolic rate is, the greater the need for food and energy. The amount of energy needed for the body to maintain itself is defined by the basal metabolic rate (BMR), which supports fundamental processes like heartbeat, respiration, and maintenance of body temperature. During physical exertion, the balance of these metabolic processes shifts to require more energy. Even moderate exercise, such as walking at a brisk pace, requires ten times the energy sitting does. To accommodate this need, the body burns the energy stored during anabolic processes (in fat tissues, for example).

Our metabolic rates naturally fluctuate through the day and the averages change throughout our lifetimes in response to age, lifestyle, and other environmental factors. Children tend to have very high BMR’s due to the energy demands of growth and their small body sizes, which require more energy to maintain body temperature. As we age, our metabolism naturally slows due to hormonal changes and reduction in muscle mass, the latter of which mediates a great portion of the body’s basal metabolic activities. Lean muscle tissue burns energy very efficiently, increasing the BMR, whereas fat cells tend to burn less, making body composition one of the key determinants in overall metabolic rate. Exercise increases BMR both by increasing lean muscle mass and keeping the body in energy expending mode, tuning it and training it to continuously burn more energy.

People may experience weight loss during sickness partly due to increased BMR, as the body expends extra energy to clear the illness. Drugs, such as nicotine or caffeine, can also increase the BMR. Eating naturally raises the BMR as the body prepares to break down the nutrients it is taking in. Dietary composition also impacts the degree of the BMR increase, with proteins raising the metabolic rate significantly higher than fats or carbohydrates. Spicy foods, such as horseradish, may also boost BMR as the body copes with the physiological responses to this type of “heat.” Likewise, not eating can radically reduce BMR, as the body enters a starvation mode to conserve energy. Certain dietary deficiencies can also lower the BMR. Iodine deficiencies, for example, can reduce BMR by interfering with proper thyroid function.

Genetics may also contribute to BMR, as can body size. Larger bodies have more tissues that can potentially contribute to the BMR, which is partly why men tend to have higher metabolism rates than women. Environmental temperature can also influence metabolism; very high or low temperature climates will require a higher BMR for maintenance of normal body temperature.

Risks of Metabolic Disorders

The specific risks of an untreated metabolic disorder depend on the nature of the disorder itself. In the case of hyperthyroidism, for example, the overactive thyroid elevates the BMR such that a person may find it very difficult to keep weight on their body, despite how much food they eat. The opposite disorder, hypothyroidism, can result in an abnormally low BMR, leading to a wide variety of physical problems. In addition to excessive weight gain, children with hypothyroidism may have developmental problems, both physical and mental. Some metabolic imbalances can also lead to fatigue, mental confusion, respiratory problems (hyperventilation), blood sugar fluctuations, and irregular heartbeat.

Causes of Metabolic Disorders

Given the complexity of metabolism, there are numerous steps where the process could be altered or disrupted. An increase or decrease in a molecule that stimulates BMR, for example, could radically raise or lower metabolism. If the catabolism pathways are interfered with, there may be buildup of toxic byproducts. Conversely, deficiencies in essential cell building blocks would deprive cells of the nutrients and energy they need. Any of these disorders could lead to serious symptoms and potentially long term health complications. Because some of these disorders are genetic, newborn babies are often tested for them to make sure that if there are special dietary or medical treatments available, the baby can begin them as soon as possible.

Some metabolic disorders are due to problems with the enzymes involved in breaking down nutrients. Galactosemia, for example, is a condition in which the body is not able to metabolize galactose, one of the sugar molecules in lactose. If this sugar cannot be broken down, it remains in the bloodstream and leads to severe complications. Babies born with galactosemia may exhibit jaundice, liver swelling, and vomiting. If galactosemia is not quickly diagnosed, it could lead to permanent damage to the brain, eyes, liver, and kidneys.

The inability to break down the amino acid phenylalanine leads to a metabolic disorder called phenylketonuria (PKU). Normally, the enzyme that metabolizes phenylalanine converts it into the amino acid tyrosine. If there is not enough of this enzyme, the phenylalanine accumulates and multiple organ systems become overloaded. The build-up of phenylalanine can block the transport of nutrients into the brain, leading to problems with proper mental development.

Both types of diabetes are also metabolic disorders arising from problems with the hormone insulin, which is one of the central signaling molecules in regulating anabolism. If insulin is not produced by the pancreas (type 1 diabetes), the body begins to use fat as an energy source, reducing the uptake of sugars into cells. This sugar can then accumulate in the blood and begin to cause a number of health complications as the body tries to release it, ultimately dehydrating the diabetic and starving their cells of nutrients. In type 2 diabetes, the body instead develops a resistance to the insulin. The downstream players awaiting the signal from insulin never get it, and are thus unresponsive.

Conventional Treatments of Metabolic Disorders

If abnormally high or low BMR’s are due to patterns within the lifestyle, they can generally be sorted out by changing behaviors. By managing the amount of energy the body brings in through the diet and expends through exercise and other physical activity, body composition that promotes good health can be achieved. For people that need to increase metabolism and lose weight, for example, this means more exercise to help build lean muscle mass in conjunction with a reduction of caloric intake.

For genetic disorders of metabolism, the treatment depends on which metabolic pathway is out of balance. Treatments are always designed to restore and maintain physiological balance. Some disorders may be balanced primarily through diet. For example, for patients with PKU, phenylalanine can be eliminated from the diet to avoid toxic buildup in the brain. Likewise, galactose can be eliminated from the diet to remove the risk of complications due to galactosemia.

Other genetic metabolic disorders can be controlled through hormonal treatments. Diabetics must routinely take injections of the hormone insulin to help rebalance their blood sugar and glucose metabolism. Those with inactive thyroid glands can take daily thyroid hormone supplements. For overactive thyroid glands, patients can take medications that block the activities of the thyroid hormones, but some also opt for surgical removal of the thyroid (or just a part of it).

Patients Medical's Treatment of Metabolic Disorders

To fully understand the nature of your metabolic disorder, we will meet with you for a comprehensive interview to discuss your diet, lifestyle, and any known medical conditions you may have. Many people can improve the balance of their BMR through diet modification and exercise, however, blood tests and other diagnostics are recommended to check your hormone levels. In getting to understand all the factors that may be impacting your BMR, we can develop a personalized program for you with therapies specifically designed to help you reach your health goals. By helping to create realistic milestones, as you take these important steps to revolutionize your lifestyle, we can help you feel a concrete sense of progress as you approach your new diet and fitness programs. By combining the strengths of both modern medicine and holistic approaches, we will rebalance your body’s chemistry to rejuvenate you and offer the sense of good health and well-being you have been looking for.

Please also see our articles on Diabetes, Hormonal Imbalance, Thyroid, Weight Loss, and Weight Gain for more information on these topics and our treatment programs for them.

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