The Science Behind Fat Metabolism
Per the usual disclaimer, always consult with your doctor before experimenting with your diet (seriously, go see a doctor, get data from blood tests, etc.). Please feel free to comment below if you’re aware of anything that should be updated; I’d appreciate knowing and I’ll update the content quickly. My goal here is to help a scientifically curious audience know the basic story and where to dive in for further study. If I’m successful, the pros will say “duh”, and everyone else will be better informed about how this all works. [UPDATE: based on a ton a helpful feedback and questions on the content below, I’ve written up a separate article summarizing the science behind ketogenic (low-carb) diets. Check it out. Also, the below content has been updated and is still very much applicable to fat metabolism on various kinds of diets. Thanks, everyone!] tl;dr The concentration of glucose in your blood is the critical upstream switch that places your body into a “fat-storing” or “fat-burning” state. The metabolic efficiency of either state — and the time it takes to get into one from the other — depends on a large variety of factors such as food and drink volume and composition, vitamin and mineral balances, stress, hydration, liver and pancreas function, insulin sensitivity, exercise, mental health, and sleep. Carbohydrates you eat, with the exception of indigestible forms like most fibers, eventually become glucose in your blood. Assuming your metabolism is functioning normally, if the switch is on you will store fat. If the switch is off, you will burn fat. Therefore, all things being equal, “diets” are just ways of hacking your body into a sufficiently low-glycemic state to trigger the release of a variety of hormones that, in turn, result in Continue reading >>
- This Incredible Detox Drink Helps You Burn Fat, Boost Metabolism, Fight Diabetes And Lower Blood Pressure.
- This Incredible Detox Drink Helps You Burn Fat, Boost Metabolism, Fight Diabetes And Lower Blood Pressure
- This Incredible Detox Drink Helps You Burn Fat, Lower Blood Pressur,Fight Diabetes And Boost Metabolism
How Are Carbohydrates Converted Into Fat Deposits?
How are carbohydrates converted into fat deposits? There are two ways that carbohydrates and body fat interact. One is directly by turning into body fat, and the other is via insulin. Turning into body fat is like adding fat into the fat cells, whereas carbohydrates spiking insulin does not add anything to fat cells per se, but hinders the release. The former is like a + equation, where the latter is a double negative which results in something that seems positive. There is a process called de novo lipogenesis (literally: Creation of fat from non-fat sources) that can occur in the body. This process turns glucose into lipids, which are then stored as body fat. This process is normally quite inefficient in the body  , which suggests that carbohydrates cannot be stored as fat to a high degree. The process can be upregulated (enhanced) if dietary fat comprised almost none of the diet (lesser than 10%, as a rough estimate), if carbohydrate intake is excessively high for a period of a few days, or if one follows an obesogenic diet (diet that is likely to make you fat) for a prolonged period of time.    Carbohydrates spike insulin , which is a hormone that mediates glucose metabolism. Insulin is not good or bad, insulin is insulin. It can be thought of as a lever that switches the body from fat burning mode into carbohydrate burning mode. This allows carbohydrates (and glycogen) to be burnt at a greater rate, but directly reduces the ability of fat to be lost. Overall metabolic rate (calories burnt over the course of a day) does not change significantly, just where the calories come from. When insulin is spiked in presence of ingested dietary fat, the dietary fat can go into body fat stores and not be released since glucose from glycogen is being used in place of Continue reading >>
Fatty Acid Metabolism
Fatty acid metabolism consists of catabolic processes that generate energy, and anabolic processes that create biologically important molecules (triglycerides, phospholipids, second messengers, local hormones and ketone bodies). Fatty acids are a family of molecules classified within the lipid macronutrient class. One role of fatty acids in animal metabolism is energy production, captured in the form of adenosine triphosphate (ATP). When compared to other macronutrient classes (carbohydrates and protein), fatty acids yield the most ATP on an energy per gram basis, when they are completely oxidized to CO2 and water by beta oxidation and the citric acid cycle. Fatty acids (mainly in the form of triglycerides) are therefore the foremost storage form of fuel in most animals, and to a lesser extent in plants. In addition, fatty acids are important components of the phospholipids that form the phospholipid bilayers out of which all the membranes of the cell are constructed (the cell wall, and the membranes that enclose all the organelles within the cells, such as the nucleus, the mitochondria, endoplasmic reticulum, and the Golgi apparatus). Fatty acids can also be cleaved, or partially cleaved, from their chemical attachments in the cell membrane to form second messengers within the cell, and local hormones in the immediate vicinity of the cell. The prostaglandins made from arachidonic acid stored in the cell membrane, are probably the most well known group of these local hormones. Fatty acid catabolism A diagrammatic illustration of the process of lipolysis (in a fat cell) induced by high epinephrine and low insulin levels in the blood. Epinephrine binds to a beta-adrenergic receptor in the cell membrane of the adipocyte, which causes cAMP to be generated inside Continue reading >>
Converting Carbohydrates To Triglycerides
Consumers are inundated with diet solutions on a daily basis. High protein, low fat, non-impact carbohydrates, and other marketing “adjectives” are abundant within food manufacturing advertising. Of all the food descriptors, the most common ones individuals look for are “fat free” or “low fat”. Food and snack companies have found the low fat food market to be financially lucrative. The tie between fat intake, weight gain, and health risks has been well documented. The dietary guidelines suggest to keep fat intake to no more than 30% of the total diet and to consume foods low in saturated and trans fatty acids. But, this does not mean that we can consume as much fat free food as we want: “Fat free does not mean calorie free.” In many cases the foods that are low in fat have a large amount of carbohydrates. Carbohydrate intake, like any nutrient, can lead to adverse affects when over consumed. Carbohydrates are a necessary macronutrient, vital for maintenance of the nervous system and energy for physical activity. However, if consumed in amounts greater than 55% to 65% of total caloric intake as recommended by the American Heart Association can cause an increase in health risks. According to the World Health Organization the Upper Limit for carbohydrates for average people is 60% of the total dietary intake. Carbohydrates are formed in plants where carbons are bonded with oxygen and hydrogen to form chains of varying complexity. The complexity of the chains ultimately determines the carbohydrate classification and how they will digest and be absorbed in the body. Mono-and disaccharides are classified as simple carbohydrates, whereas polysaccharides (starch and fiber) are classified as complex. All carbohydrates are broken down into monosaccharides before b Continue reading >>
Fat For Fuel: Why Dietary Fat, Not Glucose, Is The Preferred Body Fuel
Contrary to popular belief, glucose is NOT the preferred fuel of human metabolism; the fact is that burning dietary fat for fuel may actually be the key to optimal health Carbohydrate intake is the primary factor that determines your body's fat ratio, and processed grains and sugars (particularly fructose) are the primary culprits behind our skyrocketing obesity and diabetes rates According to experts, carbs should make up only 20 percent of your diet, while 50-70 percent of your diet should be healthy fats. Fat is far more satiating than carbs, so if you have cut down on carbs and feel ravenous, this is a sign that you need more healthy fat to burn for fuel By Dr. Mercola While we may consider ourselves to be at the pinnacle of human development, our modern food manufacturing processes have utterly failed at improving health and increasing longevity. During the Paleolithic period, many thousands of years ago, our ancestors ate primarily vegetables, fruit, nuts, roots and meat—and a wide variety of it. This diet was high in fats and protein, and low in grain- and sugar-derived carbohydrates. The average person's diet today, on the other hand, is the complete opposite, and the average person's health is a testament of what happens when you adhere to a faulty diet. Humans today suffer more chronic and debilitating diseases than ever before. And there can be little doubt that our food choices play a major role in this development. Quite simply, you were not designed to eat large amounts of refined sugar, high fructose corn syrup, cereal, bread, potatoes and pasteurized milk products. As Mark Sisson states in the featured article:1 "If you want to live a better life and eat the best foods nature provided for health and fitness, then it's time to ditch the old paradigms an Continue reading >>
Can Fats Be Turned Into Glycogen For Muscle?
The amount of fat in the average diet and the amount of stored fat in the average body make the notion of converting that fat into usable energy appealing. Glycogen, a form of energy stored in muscles for quick use, is what the body draws on first to perform movements, and higher glycogen levels result in higher usable energy. It is not possible for fats to be converted directly into glycogen because they are not made up glucose, but it is possible for fats to be indirectly broken down into glucose, which can be used to create glycogen. Relationship Between Fats and Glycogen Fats are a nutrient found in food and a compound used for long-term energy storage in the body, while glycogen is a chain of glucose molecules created by the body from glucose for short-term energy storage and utilization. Dietary fats are used for a number of functions in the body, including maintaining cell membranes, but they are not used primarily as a source of fast energy. Instead, for energy the body relies mostly on carbohydrates, which are converted into glucose that is then used to form glycogen. Turning Fats Into Glucose Excess glucose in the body is converted into stored fat under certain conditions, so it seems logical that glucose could be derived from fats. This process is called gluconeogenesis, and there are multiple pathways the body can use to achieve this conversion. Gluconeogenesis generally occurs only when the body cannot produce sufficient glucose from carbohydrates, such as during starvation or on a low-carbohydrate diet. This is less efficient than producing glucose through the metabolizing of carbohydrates, but it is possible under the right conditions. Turning Glucose Into Glycogen Once glucose has been obtained from fats, your body easily converts it into glycogen. In gl Continue reading >>
How Our Bodies Turn Food Into Energy
All parts of the body (muscles, brain, heart, and liver) need energy to work. This energy comes from the food we eat. Our bodies digest the food we eat by mixing it with fluids (acids and enzymes) in the stomach. When the stomach digests food, the carbohydrate (sugars and starches) in the food breaks down into another type of sugar, called glucose. The stomach and small intestines absorb the glucose and then release it into the bloodstream. Once in the bloodstream, glucose can be used immediately for energy or stored in our bodies, to be used later. However, our bodies need insulin in order to use or store glucose for energy. Without insulin, glucose stays in the bloodstream, keeping blood sugar levels high. Insulin is a hormone made by beta cells in the pancreas. Beta cells are very sensitive to the amount of glucose in the bloodstream. Normally beta cells check the blood's glucose level every few seconds and sense when they need to speed up or slow down the amount of insulin they're making and releasing. When someone eats something high in carbohydrates, like a piece of bread, the glucose level in the blood rises and the beta cells trigger the pancreas to release more insulin into the bloodstream. When insulin is released from the pancreas, it travels through the bloodstream to the body's cells and tells the cell doors to open up to let the glucose in. Once inside, the cells convert glucose into energy to use right then or store it to use later. As glucose moves from the bloodstream into the cells, blood sugar levels start to drop. The beta cells in the pancreas can tell this is happening, so they slow down the amount of insulin they're making. At the same time, the pancreas slows down the amount of insulin that it's releasing into the bloodstream. When this happens, Continue reading >>
Science And Nutrition :: You Are What You Ate
Over two thousand years ago, Hippocrates theorized that the body was composed of four fluids or humours including blood, phlegm, choler (yellow bile) and black bile (melancholy). Avicenna later suggested in the ninth century that these humours were derived from the process of digestion and so classified them as well as humans and all foods as hot/moist, hot/dry, cold/moist and cold/dry. Similarly, in ancient China body fluids identified resembled those put forward by Hippocrates. Additionally, the Chinese classified human characteristics, as well as foods, into yin and yang. Indian traditional medicine (ayurveda) categorizes people into three doshas or humours with their corresponding characteristics: vata (active and enthusiastic although a worrier), pitta (sharp intellectual, with a tendency to become irritable under stress) and kapha (balanced and conservative). All of these systems make a reference to the importance of balancing the internal environment of the body and, while their outlook varied, they coincide in the fact that illness was regarded as an imbalance of these components. The human body is amazing in how it protects itself and preserves life. It is indeed true that a certain level of balance or equilibrium is required to sustain life. It is critical for conditions such as temperature, hydration and energy supply to be maintained at all times. This last concept, energy supply, is a direct result of our eating habits. Out of all of these amazing chemical reactions, lets look at one group more closely: glucose metabolism. Under normal circumstances, the human body uses carbohydrates as its number one source of energy. When carbohydrates are not available in sufficient quantities to supply the body with the required energy (in the form of glucose), alterna Continue reading >>
How To Burn Stored Body Fat — A Ketosis Primer
“So, how do you tell your body to start burning stored body fat?” my friend and fellow mother asked. “Cut the carbs,” answered another mom. “I go into ketosis just about every afternoon.” “Ketosis? Isn’t that bad for you?” The short answer? No. I talk to a lot of people who want to lose weight. They try all sorts of things — exercise, calorie restriction, you name it. Sometimes, they lose the weight. Inevitably, they gain it back. That’s because what they’re doing is going on a diet — a temporary fix at best. What they need is a lifestyle change, a perspective shift, a new paradigm. Of course, you all know the paradigm I espouse — a conversion to eating real, traditional foods. Yet even a conversion to eating real food won’t necessarily help the pounds melt away. If you’re still eating 200 grams of carbohydrates a day — even if they’re “traditional” carbohydrates like sprouted or soaked grains, unrefined sweeteners, etc, you’re not going to lose weight without making some serious changes. If your body is regularly storing body fat (you gain a little bit of weight each year), then something is wrong with how your body metabolizes food. Let me introduce you to a new concept: the body fat setpoint. The body fat setpoint is the mass of body fat that your body attempts to defend against changes in either direction. It’s your body’s attempt to maintain homeostasis. This is why if you exercise more, you eat more. It’s also why if you restrict calories, your metabolism slows down to compensate. Why should you care about the body fat setpoint? From Stephan at Whole Health Source: We care because this has some very important implications for human obesity. With such a powerful system in place to keep body fat mass in a narrow range, Continue reading >>
Teaching The Body To Use Fat As Primary Energy At Rest - Changing Body Composition.
Sugar in your food generally requires little to no digesting or processing and will be in your bloodstream inside 60 minutes after eating. In response, blood sugar shoots up for a bit before coming back down rapidly a short while later. Other carbohydrates, referred to as complex carbohydrates, will be sugar in your bloodstream as well eventually. It takes your digestive system a little longer to convert complex carbs into simple sugars, so blood sugar will rise and fall a bit slower depending on a few factors. These include the type of carbohydrate (how "complex" it is) and how fibrous and/or fatty the food is. Once in the blood, your metabolism begins to use sugar in a variety of ways. Particularly if you are active or exercising, some of the sugar in your blood will be used quickly for energy. Glucose and/or fructose are the end-products of all carbohydrate breakdown. These simple sugars enter into either glycolysis (for glucose) or fructolysis (for fructose). In these processes, the metabolism uses the simple sugars to generate the compounds that, in turn, power all of the body's other metabolic processes. Put more simply, glycolysis and fructolysis convert simple sugars into energy. (A quick note on fiber: fiber is classified as a type of carbohydrate and is listed on nutrition labels under the carbohydrate section. Most fiber will pass through the body undigested. The remainder will be digested quite slowly over the course of many hours. Fiber does not have a meaningful effect on blood sugar.) Most of the time, however, sugar is not used immediately but is stored in cells for use later. This is where insulin comes into the equation. Insulin is a protein that acts as a hormone in the digestive process. When a protein is classified as a hormone, it means that it's p Continue reading >>
We Really Can Make Glucose From Fatty Acids After All! O Textbook, How Thy Biochemistry Hast Deceived Me!
Biochemistry textbooks generally tell us that we can’t turn fatty acids into glucose. For example, on page 634 of the 2006 and 2008 editions of Biochemistry by Berg, Tymoczko, and Stryer, we find the following: Animals Cannot Convert Fatty Acids to Glucose It is important to note that animals are unable to effect the net synthesis of glucose from fatty acids. Specficially, acetyl CoA cannot be converted into pyruvate or oxaloacetate in animals. In fact this is so important that it should be written in italics and have its own bold heading! But it’s not quite right. Making glucose from fatty acids is low-paying work. It’s not the type of alchemy that would allow us to build imperial palaces out of sugar cubes or offer hourly sweet sacrifices upon the altar of the glorious god of glucose (God forbid!). But it can be done, and it’ll help pay the bills when times are tight. All Aboard the Acetyl CoA! When we’re running primarily on fatty acids, our livers break the bulk of these fatty acids down into two-carbon units called acetate. When acetate hangs out all by its lonesome like it does in a bottle of vinegar, it’s called acetic acid and it gives vinegar its characteristic smell. Our livers aren’t bottles of vinegar, however, and they do things a bit differently. They have a little shuttle called coenzyme A, or “CoA” for short, that carries acetate wherever it needs to go. When the acetate passenger is loaded onto the CoA shuttle, we refer to the whole shebang as acetyl CoA. As acetyl CoA moves its caboose along the biochemical railway, it eventually reaches a crossroads where it has to decide whether to enter the Land of Ketogenesis or traverse the TCA cycle. The Land of Ketogenesis is a quite magical place to which we’ll return in a few moments, but n Continue reading >>
- International Textbook of Diabetes Mellitus, 4th Ed., Excerpt #82: Insulin Actions In Vivo: Glucose Metabolism Part 9 of 9
- World's first diabetes app will be able to check glucose levels without drawing a drop of blood and will be able to reveal what a can of coke REALLY does to sugar levels
- International Textbook of Diabetes Mellitus, 4th Ed., Excerpt #59: Mechanisms of insulin signal transduction Part 3 of 8
Fat-to-glucose Interconversion By Hydrodynamic Transfer Of Two Glyoxylate Cycle Enzyme Genes
Fat-to-glucose interconversion by hydrodynamic transfer of two glyoxylate cycle enzyme genes 1Department of Nutrition and Food Sciences, Physiology and Toxicology, University of Navarra, Pamplona, Spain 2Laboratory of Animal Physiology and Nutrition, School of Agronomy, Public University of Navarra, Pamplona, Spain Received 2008 Sep 29; Accepted 2008 Dec 10. Copyright 2008 Cordero et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The glyoxylate cycle, which is well characterized in higher plants and some microorganisms but not in vertebrates, is able to bypass the citric acid cycle to achieve fat-to-carbohydrate interconversion. In this context, the hydrodynamic transfer of two glyoxylate cycle enzymes, such as isocytrate lyase (ICL) and malate synthase (MS), could accomplish the shift of using fat for the synthesis of glucose. Therefore, 20 mice weighing 23.37 0.96 g were hydrodinamically gene transferred by administering into the tail vein a bolus with ICL and MS. After 36 hours, body weight, plasma glucose, respiratory quotient and energy expenditure were measured. The respiratory quotient was increased by gene transfer, which suggests that a higher carbohydrate/lipid ratio is oxidized in such animals. This application could help, if adequate protocols are designed, to induce fat utilization for glucose synthesis, which might be eventually useful to reduce body fat depots in situations of obesity and diabetes. Thousands of different life-related biochemical processes, such as cell respiration and many other metabolic reactions, can lead to the producti Continue reading >>
Evolving Health: Why Can't We Convert Fat To Glucose?
As evident by many sugar-laden soda pop "potbellies" of North America, lipogenesis can obviously occur from drinking and eating too much sugar (1). Wouldnt it be just grand to reverse the process and be able to lose all that fat via gluconeogenesis? Unfortunately mammals do not have the ability to synthesize glucose from fats (1). The fact is that once glucose is converted to acetyl coA there is no method of getting back to glucose. The pyruvate dehydrogenase reaction that converts pyruvate to acetyl CoA is not reversible (1p252). Because lipid metabolism produces acetyl CoA via beta-oxidation, there can be no conversion to pyruvate or oxaloacetate that may have been used for gluconeogenesis (1p252). Further, the two carbons in the acetyl CoA molecule are lost upon entering the citric acid cycle (1p252). Thus, the acetyl CoA is used for energy (1p252). There are some fatty acids that have an odd number of carbon atoms that can be converted to glucose, but these are not common in the diet (1p253). Maybe they should be made more common. Do they taste good? 1. Gropper SS, Smith JL, Groff JL. Advanced Nutrition and Human Metabolism. Belmont, CA: Thomson Wadsworth, 2009. Continue reading >>
How Does Fat Get Converted Into Energy - _
This is perhaps a little on the 'nerdy' side of questions, but is something I don't quite understand. It's not really necessary to fully understand it, to follow a 'whole foods' diet, or an 'ssos' lifestyle, but still, I would like to get my head around it. So in that regard... I understand that carbohydrates are converted into glucose, which is then used as energy in the body, and whatever energy the body does not use, it then moves into the adipose tissue, with the help of our friendly hormone called insulin. I understand that protein gets converted into amino acids, that the body then uses to restore, rebuild, and construct muscle tissue, along with other healthy tissues throughout the body. Whatever protein is not used for amino acids, is then moved into the liver, where it is converted into glucose, and at that point, the body can then use this glucose for energy. Just like our buddy, carbohydrate up above, whatever glucose (that originated from protein) that is not used for energy, can then be shuffled on over to the adipose (fat) tissue, with the help of insulin, where it is stored as body fat. Now, with Fat, this is where things get a little confusing, because my understanding, is that fat molecules can not be converted into glucose. In fact, step 1 on this journey, is that fat is utilized by the body, for fatty acids, which are required and needed for proper metabolism and biology. Whatever fat is not used for fatty acids, is then converted to triglycerides (do I got that right?), and moves on over to our adipose tissue, where it is stored as body fat. So, with that in mind, how does the body convert fat into energy, if it does not convert fat into glucose? Let me give you an example; Let's say we have a person who chooses to eat a 100% all fat diet, no protei Continue reading >>
How The Body Uses Carbohydrates, Proteins, And Fats
How the Body Uses Carbohydrates, Proteins, and Fats The human body is remarkably adept at making do with whatever type of food is available. Our ability to survive on a variety of diets has been a vital adaptation for a species that evolved under conditions where food sources were scarce and unpredictable. Imagine if you had to depend on successfully hunting a woolly mammoth or stumbling upon a berry bush for sustenance! Today, calories are mostly cheap and plentifulperhaps too much so. Understanding what the basic macronutrients have to offer can help us make better choices when it comes to our own diets. From the moment a bite of food enters the mouth, each morsel of nutrition within starts to be broken down for use by the body. So begins the process of metabolism, the series of chemical reactions that transform food into components that can be used for the body's basic processes. Proteins, carbohydrates , and fats move along intersecting sets of metabolic pathways that are unique to each major nutrient. Fundamentallyif all three nutrients are abundant in the dietcarbohydrates and fats will be used primarily for energy while proteins provide the raw materials for making hormones, muscle, and other essential biological equipment. Proteins in food are broken down into pieces (called amino acids) that are then used to build new proteins with specific functions, such as catalyzing chemical reactions, facilitating communication between different cells, or transporting biological molecules from here to there. When there is a shortage of fats or carbohydrates, proteins can also yield energy. Fats typically provide more than half of the body's energy needs. Fat from food is broken down into fatty acids, which can travel in the blood and be captured by hungry cells. Fatty aci Continue reading >>