Energy Metabolism: The Good, The Bad, and In-Between

by Konstantin Monastyrsky | Affiliate linksComments: 125

Your body casually switches from one metabolic state to another between meals, during intentional or accidental starvation, and under extreme workload or stress. This metabolic duality is very much like a hybrid engine — the moment it runs out of electricity (foods in humans), it switches over to gasoline (fat in humans), and keeps running, running, and running. In this respect, our unique physiological ability to function without food for a long while is the foundation of life itself. Alas, it also makes us fat.

These two hybrid-like states are called, respectively, anabolic and catabolic metabolism. From a weight loss perspective, anabolic metabolism drives the obesity epidemic while the catabolic enables weight loss. If that’s what you are after, you really want to befriend catabolic metabolism.

If having these two types isn’t enough already, there are also the two aspects of metabolism – one for energy regulation, another for energy utilization. When, for example, you are gaining weight because of endocrine disorders, the problem is with energy regulation. When you are perfectly healthy, but gain weight anyway, the problem is with energy utilization – a euphemism for eating too much. But in many cases, probably most, the regulation and utilization dysfunctions of metabolism run in parallel. When they combine, weight gain goes faster and weight loss slower.

The thyroid gland influences energy metabolism through the regulation of thermogenesis. A consistently lower body temperature may contribute to weight gain because the body uses less energy to keep itself warm, while a consistently high temperature may cause weight loss because the body requires more energy than the diet provides, and will catabolize protein and fat tissue to compensate for the deficit. Also, certain thyroid disorders may cause cutaneous and dermal edema (i.e. myxedema) and ensuing weight gain related to the accumulation of fluids, not fat.

Similarly, adrenal disorders contribute to weight gain because they reduce the rate of energy use for physical and mental activities. In this case, the unspent energy is converted to body fat. The adrenals don’t control energy and structural metabolism directly as does the thyroid gland.

It is worth noting that anabolic metabolism starts from the digestion and assimilation of nutrients. By “nutrients” I mean not only water, fats, proteins, carbohydrates, and alcohol (yes, it is an energy-dense nutrient), but also micronutrients – the term reserved for vitamins, minerals, and microelements that are the essential catalysts of endless metabolic reactions and regulation functions. Digestive disorders like enteritis or celiac disease result in an inability to assimilate nutrients, and will cause weight loss. Other digestive disorders, such as heartburn, gastritis, or gallstones, skew the diet toward excessive carbohydrates, and may contribute to weight gain.

Metabolism goes haywire when the thyroid gland overproduces hormones (hyperthyroidism) or the pancreas fails to produce insulin (type 1 diabetes). In both cases, the victims’ bodies literally “burn” their stores of fats and proteins to compensate for the breakdown of glucose metabolism.  Both of these problems are related to the regulation of energy metabolism, and, just like with digestive disorders, they cause weight loss, not gain.

The metabolic waters are muddied even more by the state of the respiratory function. The delivery of oxygen to the tissues is an essential part of energy metabolism. When the body isn’t getting enough oxygen because of anemia, or reduced lung capacity, or heart disease, or what have you, the exact same diet may suddenly start causing weight gain because of the reduced utilization of consumed calories.

Finally, you need to distinguish between energy and structural “metabolisms.” Your body undergoes a constant process of cell division — the old cells die off, the new take their place. This process requires a boatload of raw materials – fats, proteins, minerals, and vitamins from the foods you consume (exogenous) or from what’s already stored in the body (endogenous).  Thanks to a well-run structural metabolism, you can keep losing endogenous (body’s own) fat while still consuming a relatively satisfying reduced calorie diet.

But it all comes together once you understand the differences between anabolic and catabolic “metabolisms.”  As you well know, people don’t suddenly drop dead when they go on a hunger strike, or get lost in the wilderness without food, or fast for medical or religious reasons. Our innate ability to survive without any food for a long stretch of time has been made possible courtesy of catabolic metabolism, while anabolic metabolism is what makes catabolic possible in the first place.

Sound like Greek to you? Well, here is how it all plays out together.

Weight loss, meet your maker!

Merriam-Webster dictionary describes metabolism as “the chemical changes in living cells by which energy is provided for vital processes and activities and new material is assimilated.” This definition applies to all living cells, not just humans’.

The term metabolism itself is derived, according to the International Scientific Vocabulary, from the Greek metaballein, which, in turn, is composed of metabole (change) + ballein (to throw). In terms of a living body’s metabolism, the change means converting substances into energy, and the throw means using it.

The conversion of carbohydrates into glucose is a change; the use of glucose for energy, a throw. The conversion of glucose into body fat is a change, the use of fat for energy — a throw… That is, essentially, what the term metabolism means. To lose weight, you need to master the art of throw.

Appropriately, when we lack energy, we blame metabolism, and when a child is hyperactive, we blame it too. So it is a double-edged sword — it gives, it takes, it makes us fat, it makes us slim, it makes us lethargic, it makes us hyperactive, and on, and on, and on…

Anabolic metabolism happens to be the change part. The catabolic happens to be the throw… When your liver converts nutrients into body fat — this is anabolic metabolism in action. When your body switches over convert its own fats, proteins, and carbohydrates (glycogen) for energy — this is catabolic metabolism. In the properly managed weight loss diet, spent up fat is thrown out from under your skin. The key accent here is on “properly managed” because you only want to “throw out” fat, not muscles.

In simplified form and from a dieter’s point of view, the conversion of food into energy is anabolic metabolism. The conversion of energy stored in the body between meals as carbohydrates, fats and proteins — catabolic metabolism. Translated to our concerns, anabolic metabolism makes people fat, catabolic — slim. That is exactly what we want — to get slim, not fat, to throw, not to change (from slim to fat), catabolic — not anabolic. Anabolic — fattening; catabolic — slimming.

Sustained weight loss is catabolic metabolism in disguise. To master that art of permanent weight loss, you first need to master the art of catabolic metabolism. The body enters the catabolic state only after all sources of energy from food are completely used up. The more you ate, the longer it takes to assimilate and expend energy from consumed food. Not a big secret, really…

Better than the Prius

People who have either mastered or do not interfere with their hybrid metabolism are very much like the light, agile and thrifty Prius — they travel a lot further on a lot less fuel. A good example — the diminutive, slim Kenyans and Ethiopians, the descendants of the Masai tribe, who are — women and men alike — the consistent winners of all the world’s top marathons. In their native habitat, Masai tribesmen consume nothing but meat, dairy, and blood of ruminant (i.e. grass-eating) animals in their herds because they are peripatetic nomads and their main trade is cattle ranching, not land cultivation. They breathe thin mountain air, don’t grow crops, and do not consume much, if any, carbohydrates — the arid regions of Eastern Africa aren’t hospitable to agriculture, but provide plenty of grazing plains for their livestock.

Since these extraordinary Africans came along to compete in the marathons, the Americans, Asians, and Europeans can rarely make it into the top ten, forget about winning. For the same reason the men’s soccer never made it big in the United States — it is darn hard to find eleven guys who can run a hundred yards back and forth for almost two hours non-stop, often under the blazing sun… No, not with our carbohydrate-dominated diet…

The principle “technologies” that make these African runners win marathons (or Germans, Spaniards, Brazilians, and Argentines, also predominantly carnivore cultures, dominate professional soccer) are similar to the hybrid engine: top runners and soccer players rely on on-demand energy from proteins and fats stored in their bodies courtesy of catabolic metabolism, and they stay away from carbohydrates — quick and uncontrollable anabolic fuel. Lo and behold, their respective cultures and culinary traditions predominantly follow a carnivorous diet.

Plant-based carbohydrates are the most plentiful and rapidly available source of energy. For that reason, the term glucose metabolism is often used instead of anabolic metabolism. Though it is technically incorrect, in the context of weight loss it recognizes glucose as a primary energy source behind anabolic metabolism.

Likewise, because fat is the most abundant source of energy inside the body, the term fat metabolism is often used instead of catabolic metabolism. This is also not entirely correct because the body will not metabolize its own fat for as long as the fat derived from foods is  present in the blood in the form of triglycerides. Not only that, but this excess fat will also be dispatched for storage right under your skin – the principal mechanism of gaining weight.

The same rule applies to dietary protein – the body will not metabolize its own lean tissue for energy as long as amino acids derived from foods are still present in the blood. That is why the intake of dietary fat and protein during weight loss diets must be managed just as carefully as the intake of carbohydrates, but with a twist: you watch out for fat to prevent further weight gain and to facilitate weight loss, while you watch out for protein to prevent muscle and bone tissue wasting.

And this brings us to ketosis – a part of energy metabolism that is on everybody’s mind, thanks to the famous Atkins Diet.

Ultimate fuel or ultimate villain? It depends…

The natural catabolic process of breaking down dietary and adipose fats into usable energy produces ketones. This process starts when your body runs out of all exogenous (dietary carbohydrates) and endogenous (glycogen in liver and muscles) sources of glucose – a primary source of energy for the blood, brain, and central nervous system. When a medical professional tells you that ketones are dangerous, he or she confuses this process with alcoholic or diabetic ketoacidosis – two potentially lethal conditions.

The term ketosis was coined by late Dr. Atkins. I say “coined” because the correct term for what he had in mind is lipolysis, or the process of hydrolysis of triglycerides [fats in the bloodstream] into free fatty acids. The ensuing process produces ketones bodies – water-soluble compounds that are used for energy when glucose is in short supply.  Ketosis itself isn’t a process, but simply the presence of detectable ketones in the blood stream.

I realize it all may sound confusing or complicated, so feel free to use the term ketosis whenever describing the physiological wasting of body fat, but I prefer not to use this term because some medical doctors who equate ketosis with deadly diabetic or alcoholic ketoacidosis may “bludgeon” me to death the way they did Dr. Atkins and his eponymous diet.

When doctors are legitimately afraid about your safety, even when this concern may be unfounded, diets fail. To prevent this failure we want your doctor’s unconditional support, hence I’ll stick with the term lipolysis because it is considered safe and acceptable, an innate part of catabolic metabolism, and the primary mechanism of sustained weight loss.

Please note that the body can remain in catabolic state even when a moderate amount of carbohydrates is consumed because it will still require fats for structural metabolism. If fats are limited in the diet, then the body will utilize fats from adipose tissue. That’s how weight loss is possible without apparent ketosis.

Even though anabolic and catabolic “metabolisms” are part and parcel of life itself, the predominant groupthink about catabolic metabolism is mostly negative. This state of affairs has nothing to do with reality, and everything with vanity. Here is why:

How did catabolic metabolism get the bad rap?

If you are an athlete, and you want to build muscle — a form of stored protein — you need to consume a lot of protein-containing foods. Because muscles can’t be too big or too strong for an athlete, many use anabolic steroids to speed up muscle growth by stimulating, among other things, appetite and improving digestion — the drive behind the anabolic metabolism, or changing of food protein into muscles. (Anabolic steroids are synthetic male hormones, the derivatives of testosterone.)

The athletes’ pumped-up bodies demand a lot of energy to just move around, and lots more during the workouts and competitions. Once the energy from recently ingested food is exhausted, the body switches into catabolism to provide required energy.

The athletes’ bodies catabolize proteins stored in their muscles to provide glucose required by the body for a proper functioning of the blood, the central nervous system (CNS), and the brain. In the athletes’ parlance, this process is called appropriately muscle wasting.

Athletes keep away from too many carbohydrates, because they cause fat gain, and body fat obscures their muscles during competitive events. They do need some carbohydrates though, to spare muscle from wasting. For them, it is an endless balancing game.

To obtain enough protein to accommodate their objectives, the athletes devour steaks, fish, shrimp, lobster, and an array of processed (man-made) protein supplements from animal (mostly whey) and plant (mostly soy) origins. Health-wise, they pay a rather high price for their skewed diet. According to the experts in the field, the rate of digestive disorders in endurance athletes (not necessarily body builders) approaches 80%. Yes, eighty per cent[1]. That’s among mostly young and supposedly healthy men and women.

For athletes, catabolic muscle wasting is anathema, a curse, because it “eats” into their hard-earned muscles, and makes them less competitive… So they eat more protein to get muscle back. The information on the Internet about the virtues of anabolism, and the hell of catabolism isn’t intended for you, but for bodybuilders who aren’t overweight to begin with, and who have a very different set of goals from yours — they want to gain weight (through muscle mass), not to lose it.


You can manage your metabolism because you and only you have the power to choose the substances that your body changes into energy, and you determine how often and how much to “feed the furnace”. In other words, weight loss is nothing more than the conscious, intentional management of your metabolic “furnace” through your diet.

Embrace and employ catabolic metabolism in all its forms to attain safe and permanent weight loss. The following points outline the key concepts of catabolic metabolism:

—  Effective and permanent weight loss is attained with a help of a catabolic state – an innate function of energy and structural metabolism.

—  For as long as dietary nutrients are present in the alimentary canal and the bloodstream, the body will remain in an anabolic state.

—  Excess proteins and fats in the diet terminate the catabolic state even with zero carbohydrates in the diet, and may lead to weight-gain just like when consuming excessive carbohydrates;

—  Keeping the body in a catabolic state for extended stretches of time is the most efficient way to attain safe and natural weight loss;

– You can lose weight without apparent ketosis by allowing your body to catabolize its own fat for the needs of structural metabolism. To attain this state, you must limit fat consumption to “essential” levels.

—  The concept of a “plentiful” or “ luxurious” weight loss diet doesn’t have any bearing on actual human physiology, biochemistry, and the first law of thermodynamics which postulates that energy is invariably conserved. In terms of the human body, the excess energy is conserved as body fat.

—  The fear of the catabolic state coming from people engaged in athletics isn’t based on health-related concerns, but vanity (I will not look good) and necessity (I need strong muscles to compete.) These factors do not apply to people pursuing fat loss.

—  The loss of muscle tissue during catabolic metabolism can be mitigated by the adequate consumption of dietary proteins. Excess proteins aren’t helpful for weight loss because they terminate the catabolism of body fat.

—  The body cannot obtain essential fatty acids through catabolic metabolism, hence they must be consumed throughout the weight reduction diet.

—  In addition to essential fatty acids, the proper weight loss diet must always include an adequate amount of dietary fats to enchance satiety; to assure the release of bile from the gallbladder in order to prevent the formation of gallstones; to neutralize the astringency of bile; to assimilate fat-soluble vitamins and related minerals; and for the maintenance of intestinal mucosal membrane.

—  Avoid using the terms ketosis, ketogenic diet, or catabolic diet when communicating with medical professionals about your intentions to lose weight. Instead, use the “politically correct” terms lipolysis and  reduced calorie diet to spare well-meaning doctors from nervous breakdowns.

—  If you plan to have a scheduled medical checkup, increase the amount of easily digestible carbohydrates in advance of your appointment to rid your body of ketones. Medical doctors are on the lookout for ketones in the blood in order to screen out type 1 diabetes.

In the next three posts I plan to address the metabolism of carbohydrates, fats, and proteins, their impact on weight, and their respective roles in diet success and failure.


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[1] LJ Worobetz, and DF Gerrard, “Gastrointestinal symptoms during exercise in Enduro athletes: prevalence and speculations on the aetiology,” NZ Medical Journal, 98, no. 784 (1985): 644-6, [link] 

Previous posts from  the “Why Diets Fail?” series:

1. The Real Reason Diets Fail and What You Can Do About It

2. How Long Will It Take Me to Lose the Weight?

3. Why One Calorie For Her Is Half a Calorie For Him

4. The Top Four Misconceptions Behind Weight Loss Failure

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Cover illustration: © 2013 iStockPhoto LLP;

Posted under: Weight Loss

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