The Catabolism Of Fats And Proteins For Energy
Before we get into anything, what does the word catabolism mean? When we went over catabolic and anabolic reactions, we said that catabolic reactions are the ones that break apart molecules. To remember what catabolic means, think of a CATastrophe where things are falling apart and breaking apart. You could also remember cats that tear apart your furniture. In order to make ATP for energy, the body breaks down mostly carbs, some fats and very small amounts of protein. Carbs are the go-to food, the favorite food that cells use to make ATP but now we’re going to see how our cells use fats and proteins for energy. What we’re going to find is that they are ALL going to be turned into sugars (acetyl) as this picture below shows. First let’s do a quick review of things you already know because it is assumed you learned cell respiration already and how glucose levels are regulated in your blood! Glucose can be stored as glycogen through a process known as glycogenesis. The hormone that promotes this process is insulin. Then when glycogen needs to be broken down, the hormone glucagon, promotes glycogenolysis (Glycogen-o-lysis) to break apart the glycogen and increase the blood sugar level. Glucose breaks down to form phosphoglycerate (PGAL) and then pyruvic acid. What do we call this process of splitting glucose into two pyruvic sugars? That’s glycolysis (glyco=glucose, and -lysis is to break down). When there’s not enough oxygen, pyruvic acid is converted into lactic acid. When oxygen becomes available, lactic acid is converted back to pyruvic acid. Remember that this all occurs in the cytoplasm. The pyruvates are then, aerobically, broken apart in the mitochondria into Acetyl-CoA. The acetyl sugars are put into the Krebs citric acid cycle and they are totally broken Continue reading >>
What is Ketogenesis? Ketogenesis (1, 2) is a biochemical process that produces ketone bodies by breaking down fatty acids and ketogenic amino acids. The process supplies the needed energy of certain organs, especially the brain. Not having enough ketogenesis could result to hypoglycaemia and over production of ketone bodies leading to a condition called ketoacidosis. It releases ketones when fat is broken down for energy. There are many ways to release ketones such as through urination and exhaling acetone. Ketones have sweet smell on the breath. (3) Ketogenesis and ketoacidosis are entirely different thing. Ketoacidosis is associated with diabetes and alcoholism, which could lead to even serious condition like kidney failure and even death. Picture 1 : Ketogenic pathway Photo Source : medchrome.com Image 2 : A pyramid of ketogenic diet Photo Source : www.healthline.com What are Ketone bodies? Ketone bodies are water soluble molecules produced by the liver from fatty acids during low food intake or fasting. They are also formed when the body experienced starvation, carbohydrate restrictive diet, and prolonged intense exercises. It is also possible in people with diabetes mellitus type 1. The ketone bodies are picked up by the extra hepatic tissues and will convert to acetyl-CoA. They will enter the citric acid cycle and oxidized in the mitochondria to be used as energy. Ketone bodies are needed by the brain to convert acetyl-coA into long chain fatty acids. Ketone bodies are produced in the absence of glucose. (1, 2, 3) It is easy to detect the presence of ketone bodies. Just observe the person’s breath. The smell of the breath is fruity and sometimes described as a nail polish remover-like. It depicts the presence of acetone or ethyl acetate. The ketone bodies includ Continue reading >>
ketone body n. Any of three compounds, acetoacetic acid, acetone, and beta-hydroxybutyric acid, that are ketones or derivatives of ketones and are intermediate products of fatty acid metabolism. Ketone bodies accumulate in the blood and urine when fats are being used for energy instead of carbohydrates, as in individuals affected by starvation or uncontrolled diabetes mellitus. Also called acetone body. American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved. ketone body n (Biochemistry) biochem any of three compounds (acetoacetic acid, 3-hydroxybutanoic acid, and acetone) produced when fatty acids are broken down in the liver to provide a source of energy. Excess ketone bodies are present in the blood and urine of people unable to use glucose as an energy source, as in diabetes and starvation. Also called: acetone body Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014 ke′tone bod′y n. any of several compounds, as acetoacetic acid, acetone, and hydroxybutyric acid, that are intermediate in the metabolism of fatty acids and are produced in excessive amounts under certain abnormal conditions, as in diabetes mellitus. Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved. Noun 1. ketone body - a ketone that is an intermediate product of the breakdown of fats in the body; any of three compounds (acetoacetic acid, acetone, and/or beta-hydroxybutyric acid) found in excess in blood and urine of persons with meta Continue reading >>
D-ß-hydroxybutyrate: An Anti-aging Ketone Body
During times of starvation or limited carbohydrate consumption when glycogen stores are diminished, triglycerides in adipose tissue are broken down into fatty acids and transported to the liver. There they are catabolized to acetyl-CoA, which is then converted into the ketone bodies acetoacetate, ß-hydroxybutyrate (ßHB), and acetone which are exported from the liver. In other tissues ßHB and acetoacetate are used as energy sources, through their conversion back into acetyl-CoA, which is especially important in neurons where very little fatty acid catabolism takes place. In mitochondria ßHB is broken down into acetoacetate by ßHB dehydrogenase 1 generating NADH. The resulting acetoacetate is metabolized to acetyl-CoA through acetoacetyl-CoA and is further broken down leading to the production of NADH and FADH2 as part of the citric acid cycle. ßHB has shown some effectiveness in the protection against Alzheimer's and Parkinson's disease-mediated neurodegeneration in animal models and human trials , but not much is known about its effects on the aging process itself. Moreover, the mechanisms through which ßHB are protective are not entirely clear. Recent evidence suggests that ßHB protects against oxidative stress through its action as an endogenous class I and class IIa histone deacetylase (HDAC) inhibitor to increase expression of oxidative stress resistance factors such as FoxO3A and MT2 (metallothionein 2) . This is not without precedent as the structurally related HDAC inhibitor butyrate has been shown to be protective in mammalian disease models and to extend lifespan in C. elegans . ßHB levels have been shown to increase to roughly 1-2 mM levels in the plasma during fasting or to 0.6 mM during calorie restriction (CR) , a 20%-40% lowering of ca Continue reading >>
Keto Diet Science: How Your Body Burns Fat
By now, you’ve probably heard about the keto diet. You've probably heard that it all but bans carbs and sugars, or that it's been clinically shown to reduce epileptic seizures in kids, or even that it helps people condition their bodies to burn fat. As we detailed in our recent feature on the keto diet, all of those things are true. But as any bodybuilder knows, you don't need to be on the keto diet to burn fat. Heck, you can do it with a focused meal and exercise plan. So we've been wondering: When your body "burns fat" for energy, what's really going on there? How exactly does the keto diet work? And why the hell is it called the "keto" diet, anyway? Play Video Play Loaded: 0% Progress: 0% Remaining Time -0:00 This is a modal window. Foreground --- White Black Red Green Blue Yellow Magenta Cyan --- Opaque Semi-Opaque Background --- White Black Red Green Blue Yellow Magenta Cyan --- Opaque Semi-Transparent Transparent Window --- White Black Red Green Blue Yellow Magenta Cyan --- Opaque Semi-Transparent Transparent Font Size 50% 75% 100% 125% 150% 175% 200% 300% 400% Text Edge Style None Raised Depressed Uniform Dropshadow Font Family Default Monospace Serif Proportional Serif Monospace Sans-Serif Proportional Sans-Serif Casual Script Small Caps Defaults Done Well strap some protective boxing headgear over those thinking caps, bros, because we’re about to roundhouse kick you in the brain with some KNOWLEDGE. (For a detailed breakdown of the chemistry at work, be sure to check out our references: this explainer on ketone bodies from the University of Waterloo, and this ketosis explainer from Rose-Hulman Institute of Technology [PDF], plus our feature on the keto diet from the July/August issue of Men's Fitness.) Why does the body go into fat-burning mode? For most pe Continue reading >>
Does Fat Convert To Glucose In The Body?
Your body is an amazing machine that is able to extract energy from just about anything you eat. While glucose is your body's preferred energy source, you can't convert fat into glucose for energy; instead, fatty acids or ketones are used to supply your body with energy from fat. Video of the Day Fat is a concentrated source of energy, and it generally supplies about half the energy you burn daily. During digestion and metabolism, the fat in the food you eat is broken down into fatty acids and glycerol, which are emulsified and absorbed into your blood stream. While some tissues -- including your muscles -- can use fatty acids for energy, your brain can't convert fatty acids to fuel. If you eat more fat than your body needs, the extra is stored in fat cells for later use. Fat has more than twice as many calories per gram as carbs and protein, which makes it an efficient form of stored energy. It would take more than 20 pounds of glycogen -- a type of carbohydrate used for fuel -- to store the same amount of energy in just 10 pounds of fat. Your Body Makes Glucose From Carbs Almost all the glucose in your body originated from carbohydrates, which come from the fruit, vegetables, grains and milk in your diet. When you eat these carb-containing foods, your digestive system breaks them down into glucose, which is then used for energy by your cells. Any excess glucose is converted into glycogen, then stored in your muscles and liver for later use. Once you can't store any more glucose or glycogen, your body stores any leftover carbs as fat. Glucose is your brain's preferred source of energy. However, when glucose is in short supply, your brain can use ketones -- which are derived from fat -- for fuel. Since your brain accounts for approximately one-fifth of your daily calori Continue reading >>
Ketogenesis pathway. The three ketone bodies (acetoacetate, acetone, and beta-hydroxy-butyrate) are marked within an orange box Ketogenesis is the biochemical process by which organisms produce a group of substances collectively known as ketone bodies by the breakdown of fatty acids and ketogenic amino acids. This process supplies energy to certain organs (particularly the brain) under circumstances such as fasting, but insufficient ketogenesis can cause hypoglycemia and excessive production of ketone bodies leads to a dangerous state known as ketoacidosis. Production Ketone bodies are produced mainly in the mitochondria of liver cells, and synthesis can occur in response to an unavailability of blood glucose, such as during fasting. Other cells are capable of carrying out ketogenesis, but they are not as effective at doing so. Ketogenesis occurs constantly in a healthy individual. Ketogenesis takes place in the setting of low glucose levels in the blood, after exhaustion of other cellular carbohydrate stores, such as glycogen. It can also take place when there is insufficient insulin (e.g. in type 1 (but not 2) diabetes), particularly during periods of "ketogenic stress" such as intercurrent illness. The production of ketone bodies is then initiated to make available energy that is stored as fatty acids. Fatty acids are enzymatically broken down in β-oxidation to form acetyl-CoA. Under normal conditions, acetyl-CoA is further oxidized by the citric acid cycle (TCA/Krebs cycle) and then by the mitochondrial electron transport chain to release energy. However, if the amounts of acetyl-CoA generated in fatty-acid β-oxidation challenge the processing capacity of the TCA cycle; i.e. if activity in TCA cycle is low due to low amo Continue reading >>
What Are Ketones?
With the gradual resurgence of low-carb diets in recent years, the word “ketones” is thrown around a lot. But many people aren’t really aware of the details. What are ketones, really? And what do they do in the body? There can be a lot of misinformation regarding the answers to these questions, so read on for a full overview of ketones and their role in a ketogenic diet. Ketones, also known as “ketone bodies,” are byproducts of the body breaking down fat for energy that occurs when carbohydrate intake is low. Here’s how it works: When there isn’t a sufficient level of available glucose — which is what the body uses for its main source of fuel — and glycogen levels are depleted, blood sugar and insulin are lowered and the body looks for an alternative source of fuel: in this case, fat. This process can happen when a person fasting, after prolonged exercise, during starvation, or when eating a low-carb, ketogenic diet. And when the body begins breaking down fats for energy like this, a process known as beta-oxidation, ketones are formed for use as fuel for the body and brain. This is known as ketosis. People following a ketogenic diet specifically reduce their carbohydrate intake for this reason: to create ketones for energy. Many people use the benefits of ketosis — less reliance on carbs and more burning of fat — to possibly help lower blood pressure, reduce cravings, improve cholesterol, increase weight loss, improve energy, and more. TYPES OF KETONE BODIES So, what else about ketones do we need to know? To start, there are technically three types of ketone bodies: Acetoacetate (AcAc) Beta-hydroxybutyric acid (BHB) Acetone Both acetoacetate and beta-hydroxybutyrate are responsible for transporting energy from the liver to other tissues in the body Continue reading >>
How Ketogenesis And Ketones Treat Inflammation
Intro Inflammation is a biological mechanism our bodies use to deal with internal and external events, such as combatting infections, repairing tissues or mitigating the immediate consequences of a fractured bone. However, it often carries a negative connotation since many diseases provoke symptoms through the process of inflammation. So although it is absolutely necessary for keeping the human body functioning properly, like so many things in biology, too much or too little is the problem. Inflammation can be managed with and without drugs. Here we will focus on ketogenesis and ketones with regards to treating inflammation since both drug and drug-free approaches can be discussed. What is ketogenesis? Ketogenesis is the process whereby your body produces molecules called ketone bodies, also known as ketones (see What’s a Ketone?). More specifically, ketogenesis is a series of biochemical reactions that builds molecules (ketones) from parts of other ones (like 2 acetyl-CoA molecules). How ketone bodies are formed? Fellow nerds can gaze upon the ketogenesis pathway below (1) whilst the non-initiated can simply keep in mind that our liver is ground-zero for ketogenesis. This is where fat is used as the raw material to produce 3 kinds of ketone bodies. Humans are remarkably good at ketogenesis. Just for comparison, dogs too can make ketones but the degree to which they require protein, carbohydrate or caloric restriction to do so is greater (2,3). Once you’ve produced enough ketones by upregulating ketogenesis, you eventually move into a metabolic state called ketosis. People are in ketosis when they are on a diet low enough in carbohydrates, known as a ketogenic diet, or when eating very very little if any food at all for example. What a ketogenic diet and fasting hav Continue reading >>
Excess ketones are dangerous for someone with diabetes... Low insulin, combined with relatively normal glucagon and epinephrine levels, causes fat to be released from fat cells, which then turns into ketones. Excess formation of ketones is dangerous and is a medical emergency In a person without diabetes, ketone production is the body’s normal adaptation to starvation. Blood sugar levels never get too high, because the production is regulated by just the right balance of insulin, glucagon and other hormones. However, in an individual with diabetes, dangerous and life-threatening levels of ketones can develop. What are ketones and why do I need to know about them? Ketones and ketoacids are alternative fuels for the body that are made when glucose is in short supply. They are made in the liver from the breakdown of fats. Ketones are formed when there is not enough sugar or glucose to supply the body’s fuel needs. This occurs overnight, and during dieting or fasting. During these periods, insulin levels are low, but glucagon and epinephrine levels are relatively normal. This combination of low insulin, and relatively normal glucagon and epinephrine levels causes fat to be released from the fat cells. The fats travel through the blood circulation to reach the liver where they are processed into ketone units. The ketone units then circulate back into the blood stream and are picked up by the muscle and other tissues to fuel your body’s metabolism. In a person without diabetes, ketone production is the body’s normal adaptation to starvation. Blood sugar levels never get too high, because the production is regulated by just the right balance of insulin, glucagon and other hormones. However, in an individual with diabetes, dangerous and life-threatening levels of ketone Continue reading >>
Ketone bodies Acetone Acetoacetic acid (R)-beta-Hydroxybutyric acid Ketone bodies are three water-soluble molecules (acetoacetate, beta-hydroxybutyrate, and their spontaneous breakdown product, acetone) that are produced by the liver from fatty acids during periods of low food intake (fasting), carbohydrate restrictive diets, starvation, prolonged intense exercise,, alcoholism or in untreated (or inadequately treated) type 1 diabetes mellitus. These ketone bodies are readily picked up by the extra-hepatic tissues, and converted into acetyl-CoA which then enters the citric acid cycle and is oxidized in the mitochondria for energy. In the brain, ketone bodies are also used to make acetyl-CoA into long-chain fatty acids. Ketone bodies are produced by the liver under the circumstances listed above (i.e. fasting, starving, low carbohydrate diets, prolonged exercise and untreated type 1 diabetes mellitus) as a result of intense gluconeogenesis, which is the production of glucose from non-carbohydrate sources (not including fatty acids). They are therefore always released into the blood by the liver together with newly produced glucose, after the liver glycogen stores have been depleted (these glycogen stores are depleted after only 24 hours of fasting). When two acetyl-CoA molecules lose their -CoAs, (or Co-enzyme A groups) they can form a (covalent) dimer called acetoacetate. Beta-hydroxybutyrate is a reduced form of acetoacetate, in which the ketone group is converted into an alcohol (or hydroxyl) group (see illustration on the right). Both are 4-carbon molecules, that can readily be converted back into acetyl-CoA by most tissues of the body, with the notable exception of the liver. Acetone is the decarboxylated form of acetoacetate which cannot be converted Continue reading >>
Checking Urine Glucose And Ketones
Checking urine for ketones Urinary ketones are checked by dipping a chemically treated strip in a fresh sample of urine. The colour change is then compared to a chart. A purple colour means ketones are in the urine. Ketones are a sign that too much fat has broken down in the body. There may be a number of causes, such as too little insulin or the stress of an illness. Ketones are a cause for concern if they are present when the blood glucose is high (greater than 14 mmol/L or 250 mg/dL). Check urine ketones whenever: the blood sugar level is over 14 mmol/L (250 mg/dL) for 3 readings in a row your child is feeling ill, has a fever, or has vomited your child has symptoms of high blood sugar, such as increased thirst and urination the diabetes team asks you to check for ketones, perhaps when the insulin dose is being adjusted Have strips at home for ketone checking at all times. Make sure that the strips have not expired by checking the expiration date on the bottle. The bottle should be kept closed. Once the bottle is open, the strips must be used within 6 months. Note that strips are available to check for glucose as well as ketones in the urine. Follow the instructions on the package carefully, and ask your health care team for help if the instructions are not clear. Checking urine for sugar Sugar in the urine is usually checked only as a back-up to checking blood sugar, or to screen other family members. A chemically treated strip is dipped briefly into a fresh urine sample. The strip will change colour. After a certain period of time the strip will be compared with a colour chart on the box. A urine check showing no sugar means that when the urine was made the blood sugar level was below the renal (kidney) threshold (about 8.0 to 12.0 mmol/L, or 145 to 220 mg/dL). A u Continue reading >>
Introductory discusion of fat metabolism, exercise, and fasting. Fatty acids can be used as the major fuel for tissues such as muscle, but they cannot cross the blood-brain barrier, and thus cannot be used by the central nervous system (CNS). This becomes a major problem during starvation (fasting), particularly for organisms such as ourselves in which CNS metabolism constitute a major portion of the resting basal metabolic rate. These organism must provide glucose to the CNS to provide for metabolic needs, and thus during the initial fasting period must break down substantial amounts of muscle tissue (protein) to provide the amino acid precursors of gluconeogenesis. Obviously the organism could not survive long under such a regime. What is needed is an alternate fuel source based on fat rather than muscle. The so-called ketone bodies serve this function: Note that only two of the ketone bodies are in fact ketones, and that acetone is an "unintentional" breakdown product resulting from the instability of acetoacetate at body temperature. Acetone is not available as fuel to any significant extent, and is thus a waste product. CNS tissues can use ketone bodies any time, the problem is the normally very low concentrations (< 0.3 mM) compared to glucose (about 4 mM). Since the KM's for both are similar, the CNS doesn't begin to use ketone bodies in preference to glucose until their concentration exceed's the concentration of glucose in the serum. The system becomes saturated at about 7 mM. The limiting factor in using ketone bodies then becomes the ability of the liver to synthesis them, which requires the induction of the enzymes required for acetoacetate biosynthesis. Normal glucose concentrations inhibit ketone body synthesis, thus the ketone bodies will only begin to be Continue reading >>
How Dka Happens And What To Do About It
Certified Diabetes Educator Gary Scheiner offers an overview of diabetic ketoacidosis. (excerpted from Think Like A Pancreas: A Practical Guide to Managing Diabetes With Insulin by Gary Scheiner MS, CDE, DaCapo Press, 2011) Diabetic Ketoacidosis (DKA) is a condition in which the blood becomes highly acidic as a result of dehydration and excessive ketone (acid) production. When bodily fluids become acidic, some of the body’s systems stop functioning properly. It is a serious condition that will make you violently ill and it can kill you. The primary cause of DKA is a lack of working insulin in the body. Most of the body’s cells burn primarily sugar (glucose) for energy. Many cells also burn fat, but in much smaller amounts. Glucose happens to be a very “clean” form of energy—there are virtually no waste products left over when you burn it up. Fat, on the other hand, is a “dirty” source of energy. When fat is burned, there are waste products produced. These waste products are called “ketones.” Ketones are acid molecules that can pollute the bloodstream and affect the body’s delicate pH balance if produced in large quantities. Luckily, we don’t tend to burn huge amounts of fat at one time, and the ketones that are produced can be broken down during the process of glucose metabolism. Glucose and ketones can “jump into the fire” together. It is important to have an ample supply of glucose in the body’s cells. That requires two things: sugar (glucose) in the bloodstream, and insulin to shuttle the sugar into the cells. A number of things would start to go wrong if you have no insulin in the bloodstream: Without insulin, glucose cannot get into the body’s cells. As a result, the cells begin burning large amounts of fat for energy. This, of course, Continue reading >>
What Is Acetoacetate?
When following a ketogenic diet, measuring ketone levels in the body is an important part of maintaining a healthy level of ketosis. There are three types of ketones created in the body, and it’s helpful to know the different roles each type plays, both for monitoring their levels and for understanding the ketosis process. In this article, we’re zeroing in on just one of those ketone bodies: acetoacetate. So, what is acetoacetate and how exactly does it fit into ketosis? To answer that question, let’s step back outside the aquarium (so-to-speak) and review what’s happening in ketosis. What is Acetoacetate in Terms of the Ketogenic Diet For most of us, the most common source of fuel for the body is glucose, because it is readily available when we eat foods containing carbohydrates, such as breads, pastas, sugars, fruits, or starches. When we digest carbs, they either turn immediately into glucose for the body to use or are stored as glycogen within our muscles, liver, and brain. However, if there aren’t sufficient levels of carb intake, such as when someone is on a ketogenic diet (low carb, moderate protein, and high fat), the body will shift to break down fat for fuel instead. During this process, which is known as ketogenesis, ketones like acetoacetate are formed by the liver. The goal of those on the ketogenic diet it to rely on ketones as a primary fuel. There are three main types of ketone bodies that can be detected in the bloodstream during ketosis. The body creates acetoacetate first. Then, BHB is created from acetoacetate, and acetone is created spontaneously as a byproduct of acetoacetate. Acetoacetate is converted into BHB, which is the rich source of energy for the brain we care about. This process of converting fatty acids to ketone bodies is essen Continue reading >>