Ketosis (IPA pronunciation: [ki'tosɪs]) is a stage in metabolism occurring when the liver converts fat into fatty acids and ketone bodies which can be used by the body for energy. It was identified by Dr. Stephen Moody in 1969. Articles with similar titles include the NATO phonetic alphabet, which has also informally been called the “International Phonetic Alphabet”. For information on how to read IPA transcriptions of English words, see IPA chart for English. ... A few of the metabolic pathways in a cell. ... The liver is an organ present in vertebrates and some other animals. ... This article is about lipid molecules, for FAT see File Allocation Table. ... In chemistry, especially biochemistry, a fatty acid is a carboxylic acid often with a long unbranched aliphatic tail (chain), which is either saturated or unsaturated. ... Ketone bodies are three chemicals that are produced as by-products when fatty acids are broken down for energy. ...

Metabolic pathways

Most medical resources regard ketosis as a pathological state associated with chronic starvation. Glucose is regarded as the preferred energy source for all cells in the body with ketosis being regarded as a crisis reaction of the body to a lack of carbohydrates in the diet. In recent years this viewpoint, both the body's preference for glucose and the dangers associated with ketosis, has been challenged by some doctors.^[1][2][3] Pathology (from Greek pathos, feeling, pain, suffering; and logos, study of; see also -ology) is the study of the processes underlying disease and other forms of illness, harmful abnormality, or dysfunction. ... A female child during the Nigerian-Biafran war of the late 1960s, shown suffering the effects of severe hunger and malnutrition. ...

Ketone bodies, from the breakdown of fatty acids to acetyl groups, are also produced during this state, and are burned throughout the body. Excess ketone bodies will slowly decarboxylate into acetone. That molecule is excreted in the breath and urine. The brain has a residual need for glucose because ketones can only provide energy when used during aerobic respiration in mitochondria. In the long thin neurons, much of the metabolically active cellular membrane must derive its energy from glucose via anaerobic respiration without the assistance of mitochondria. Ketone bodies are three chemicals that are produced as by-products when fatty acids are broken down for energy. ... The chemical compound acetone (also known as propanone, dimethyl ketone, 2-propanone, propan-2-one and β-ketopropane) is the simplest representative of the ketones. ... Breathing transports oxygen into the body and carbon dioxide out of the body. ... This article or section is in need of attention from an expert on the subject. ... This article or section should be merged with aerobic metabolism. ... In cell biology, a mitochondrion is an organelle found in the cells of most eukaryotes. ... // The cell membrane (also called the plasma membrane or plasmalemma) is a semipermeable lipid bilayer common to all living cells. ... Anaerobic respiration refers to the oxidation of molecules in the absence of oxygen to produce energy, in opposition to Aerobic respiration which does use oxygen. ...

When glycogen stores are not available in the cells (glycogen is primarily created when carbohydrates such as starch and sugar are consumed in the diet), fat (triacylglycerol) is cleaved to give 3 fatty acid chains and 1 glycerol molecule in a process called lipolysis. Most of the body is able to utilize fatty acids as an alternative source of energy in a process where fatty acid chains are cleaved to form acetyl-CoA, which can then be fed into the Krebs Cycle. During this process a high concentration of glucagon is present in the serum and this inactivates glucose kinase causing most cells in the body to use fatty acids as their primary energy source. At the same time, glucose is synthesized in the liver from lactic acid, glucogenic amino acids, and glycerol, in a process called gluconeogenesis. This glucose is used exclusively for energy by cells such as neurons and red blood cells.^{[citation needed]} Electron micrograph of a section of a liver cell showing glycogen deposits as accumulations of electron dense particles (arrows). ... Carbohydrates (literally hydrates of carbon) are chemical compounds that act as the primary biological means of storing or consuming energy, other forms being fat and protein. ... Starch (CAS# 9005-25-8) is a complex carbohydrate which is soluble in water; it is used by plants as a way to store excess glucose. ... Magnification of grains of sugar, showing their monoclinic hemihedral crystalline structure. ... This article is about lipid molecules, for FAT see File Allocation Table. ... Glycerol, also well known as glycerin and glycerine, and less commonly as propane-1,2,3-triol, 1,2,3-propanetriol, 1,2,3-trihydroxypropane, glyceritol, and glycyl alcohol, is a colorless, odorless, hygroscopic, and sweet-tasting viscous liquid. ... Lipolysis is the breakdown of fat stored in fat cells. ... Categories: Biochemistry stubs | Thiols ... Overview of the citric acid cycle The citric acid cycle (also known as the tricarboxylic acid cycle, the TCA cycle, or the Krebs cycle, after Hans Adolf Krebs who identified the cycle) is a series of chemical reactions of central importance in all living cells that use oxygen as part... Glucagon ball and stick model A microscopic image stained for glucagon. ... Glucose (Glc), a monosaccharide (or simple sugar), is the most important carbohydrate in biology. ... Lactic acid (IUPAC systematic name: 2-hydroxypropanoic acid), also known as milk acid, is a chemical compound that plays a role in several biochemical processes. ... Phenylalanine is one of the standard amino acids. ... Pyruvic acid Oxaloacetic acid Phosphoenolpyruvate Fructose 1,6-bisphosphate Fructose 6-phosphate Glucose-6-phosphate Glucose Gluconeogenesis is the generation of glucose from non-sugar carbon substrates like pyruvate, lactate, glycerol, and amino acids (primarily alanine and glutamine). ... Neurons (also called nerve cells) are the primary cells of the nervous system. ... Human red blood cells Red blood cells are the most common type of blood cell and are the vertebrate bodys principal means of delivering oxygen to body tissues via the blood. ...

Similar conditions

Ketosis should not be confused with ketoacidosis (diabetic ketoacidosis or the less common alcoholic ketoacidosis), which is severe ketosis causing the pH of the blood to drop below 7.2. Ketoacidosis is a medical condition usually caused by diabetes and accompanied by dehydration, hyperglycemia, ketonuria and increased levels of glucagon. The high glucagon, low insulin serum levels signals the body to produce more glucose via gluconeogenesis, glycogenolysis and ketogenesis. High levels of glucose causes the failure of tubular reabsorption in the kidneys, causing water to leak into the tubules in a process called osmotic diuresis, causing dehydration and further exacerbating the acidosis. It has been suggested that this article or section be merged with Diabetic ketoacidosis. ... This article is about the disease that features high blood sugar. ... Dehydration (hypohydration) is the removal of water (hydro in ancient Greek) from an object. ... Hyperglycemia or High Blood Sugar is a condition in which an excessive amount of glucose circulates in the blood plasma. ... Pyruvic acid Oxaloacetic acid Phosphoenolpyruvate Fructose 1,6-bisphosphate Fructose 6-phosphate Glucose-6-phosphate Glucose Gluconeogenesis is the generation of glucose from non-sugar carbon substrates like pyruvate, lactate, glycerol, and amino acids (primarily alanine and glutamine). ... Glycogen Glucose Glucose-6-phosphate Glycogenolysis is the catabolism of glycogen by removal of a glucose monomer and addition of phosphate to produce glucose-1-phosphate. ... Ketogenesis is the process by which ketone bodies are produced as a result of fatty acid breakdown. ... Renal physiology is the study of the physiology of the kidneys. ... Osmotic diuresis occurs when substances of high molecular weight, for example glucose, find their way into the kidney tubules. ...

Since non-medically trained people often confuse ketosis with ketoacidosis, Dr Robert Atkins proposed that ketosis that occurs through deliberate carbohydrate restriction be referred to as "benign dietary ketosis."

Diet

If the diet is changed from a highly glycemic diet to a diet that does not substantially contribute to blood glucose, the body goes through a set of stages to enter ketosis. During the initial stages of this process the adult brain does not burn ketones, however the newborn brain makes immediate use of this important substrate for lipid synthesis in the brain. After about 48 hours of this process, the adult brain starts burning ketones in order to more directly utilize the energy from the fat stores that are being depended upon, and to reserve the glucose only for its absolute needs, thus avoiding the depletion of the body's protein store in the muscles. Glycemic index (also glycaemic index, GI) is a ranking system for carbohydrates based on their immediate effect on blood glucose levels. ... In medicine, blood sugar is glucose in the blood. ... In animals the brain, or encephalon (Greek for in the head), is the control center of the central nervous system, responsible for thought. ...

Whether ketosis takes place can be checked by using special urine test strips such as Ketostix. Ketostix is Bayers brand name for test strips designed to measure the level of ketones in the urine. ...

Deliberately induced ketosis through a low-carbohydrate diet has been used to treat medical conditions although most such treatments remain controversial.^{[4] [5]} The ketogenic diet is an approach to treating epilepsy, and the Atkins Nutritional Approach (and many similar diets) is marketed for treating obesity. The very low calorie, medically supervised Bernstein, Lighter Life, Lindora diets and Medifast also use ketosis for weight loss. [4][5] [6] Low-carbohydrate diets or low carb diets are nutritional programs that advocate restricted carbohydrate consumption, based on research that ties consumption of certain carbohydrates with increased blood insulin levels, and overexposure to insulin with metabolic syndrome (the most recognized symptom of which is obesity). ... The ketogenic diet is a very high fat diet that relies on inducing a state of ketosis. ... The Atkins Nutritional Approach, popularly known as the Atkins Diet or just Atkins, is the most marketed and well-known of the low-carbohydrate diets. ...

See Also

• Ketoacidosis
• Ketogenic diet
• Ketonuria
• Low-carbohydrate diet

It has been suggested that this article or section be merged with Diabetic ketoacidosis. ... The ketogenic diet is a very high fat diet that relies on inducing a state of ketosis. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Low-carbohydrate diets or low carb diets are nutritional programs that advocate restricted carbohydrate consumption, based on research that ties consumption of certain carbohydrates with increased blood insulin levels, and overexposure to insulin with metabolic syndrome (the most recognized symptom of which is obesity). ...

References

• Diabetic Ketoacidosis
• NHS Direct: Ketosis
• Breath acetone is a reliable indicator of ketosis in adults consuming ketogenic meals, American Journal of Clinical Nutrition.

Further reading

The Merck Manual -

Diabetic Ketoacidosis

Alcoholic Ketoacidosis

Notes