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 >>
Not to be confused with Glycogenesis or Glyceroneogenesis. Simplified Gluconeogenesis Pathway Gluconeogenesis (GNG) is a metabolic pathway that results in the generation of glucose from certain non-carbohydrate carbon substrates. From breakdown of proteins, these substrates include glucogenic amino acids (although not ketogenic amino acids); from breakdown of lipids (such as triglycerides), they include glycerol (although not fatty acids); and from other steps in metabolism they include pyruvate and lactate. Gluconeogenesis is one of several main mechanisms used by humans and many other animals to maintain blood glucose levels, avoiding low levels (hypoglycemia). Other means include the degradation of glycogen (glycogenolysis) and fatty acid catabolism. Gluconeogenesis is a ubiquitous process, present in plants, animals, fungi, bacteria, and other microorganisms. In vertebrates, gluconeogenesis takes place mainly in the liver and, to a lesser extent, in the cortex of the kidneys. In ruminants, this tends to be a continuous process. In many other animals, the process occurs during periods of fasting, starvation, low-carbohydrate diets, or intense exercise. The process is highly endergonic until it is coupled to the hydrolysis of ATP or GTP, effectively making the process exergonic. For example, the pathway leading from pyruvate to glucose-6-phosphate requires 4 molecules of ATP and 2 molecules of GTP to proceed spontaneously. Gluconeogenesis is often associated with ketosis. Gluconeogenesis is also a target of therapy for type 2 diabetes, such as the antidiabetic drug, metformin, which inhibits glucose formation and stimulates glucose uptake by cells. In ruminants, because dietary carbohydrates tend to be metabolized by rumen organisms, gluconeogenesis occurs Continue reading >>
Modern Diet Myth No. 4: Fructose Turns To Fat
Modern Diet Myth No. 4: Fructose turns to fat Fructose the dietary villain de jour is currently giving rise to more myths than anything else and they all seem to relate to fat. Fructose supposedly leads to fatty liver and too much fat in the blood. To top it off, fructose is said to be uniquely fattening! Where do we start? Most of the carbohydrate we eat ends up in the bloodstream as either glucose or fructose. The myth goes that glucose is the good sugar as it is used to power the brain, the muscles and most of the cells in the body. And the fructose is the bad sugar which is quickly taken up by the liver and turned into fat, giving rise to fatty liver. Unfortunately for the myth-makers, no reputable health authority in the world agrees. Fatty liver is certainly a common problem but the experts see it as part of the metabolic syndrome a cluster of abnormalities linked to central obesity and insulin resistance, where the cells of the body become less sensitive to insulin. There is no recommended diet for fatty liver. Instead, health authorities encourage people with fatty liver to lose some weight and increase their physical activity, both of which improve insulin resistance. Our liver certainly has the ability to turn both glucose and fructose into fat its the perfect way to turn any excess carbohydrate calories into a form that can be stored for later use. And sooner or later this fat appears in the blood as triglycerides. However, the idea that all the fructose we eat turns to fat pushing up the level of triglycerides in the blood is just plain wrong. If you are a healthy, normal weight person eating enough food to maintain your body weight your liver only turns a tiny fraction of fructose into fat , about 1-3%. Most of the fructose taken up by the liver is actuall 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 >>
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 >>
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 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 >>
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 >>
Do Fat And Protein Turn Into Glucose?
Sandi Busch received a Bachelor of Arts in psychology, then pursued training in nursing and nutrition. She taught families to plan and prepare special diets, worked as a therapeutic support specialist, and now writes about her favorite topics nutrition, food, families and parenting for hospitals and trade magazines. Glucose keeps you energized.Photo Credit: Ridofranz/iStock/Getty Images When blood glucose gets low, your energy plummets and you may find it hard to concentrate. Your body can temporarily fill the gap by drawing on glucose stored in your liver, but those supplies are limited. When they run out, your body can produce glucose from fats and proteins. Fats are good for backup energy, but your body doesnt like to divert protein into energy due to its other vital functions. The best way to keep your body fueled is to consume the right amount of fats, proteins and carbs. Carbohydrates consist of molecules of sugar, which your body digests into glucose and uses for energy. When youre short on carbs, glucose can be created from fat and protein in a process called gluconeogenesis. Gluconeogenesis takes place mostly in your liver, which also has the job of maintaining a steady amount of glucose in your blood. If blood sugar drops too low due to problems in the liver, your kidneys can boost blood sugar by converting the amino acid glutamine into glucose. The saturated and unsaturated fats in your diet consist of two substances bound together: glycerol and fatty acids. During digestion, they're separated, and each one follows a different path. Glycerol is easily metabolized and used to make glucose. Fatty acids are carried to tissues throughout your body, where they help build cell walls, produce hormones and digest fat-soluble nutrients. Fatty acids can be converted i Continue reading >>
Protein Will Not Make You Fat
Here's what you need to know... While it's biochemically possible for protein to turn into fat by ingesting extremely high numbers of calories or extremely large amounts of protein, it's unlikely you'll ever be in that situation. You can pretty much eat as much protein as you want and it won't turn to fat. That old chestnut about only being able to absorb 30 grams of protein in one sitting is bunk. Aside from building muscle, protein provides essential amino acids that serve as the building blocks for other proteins, enzymes, and hormones within the body that are vital for normal functioning. Without this steady supply of amino acids, the body resorts to breaking down its own proteins – typically from muscle – in order to meet this demand. Protein has its share of misconceptions. It's not uncommon to hear claims that dietary protein eaten in excess of some arbitrary number will be stored as body fat. Even those who are supposed to be reputable sources for nutrition information propagate this untenable dogma. While paging through a nutrition textbook I came across a section in the protein chapter regarding amino acids and energy metabolism (1). To quote the book directly: "Eating extra protein during times of glucose and energy sufficiency generally contributes to more fat storage, not muscle growth. This is because, during times of glucose and energy excess, your body redirects the flow of amino acids away from gluconeogenesis and ATP-producing pathways and instead converts them to lipids. The resulting lipids can subsequently be stored as body fat for later use." This is, more or less, supported by another textbook I own (2): "In times of excess energy and protein intakes coupled with adequate carbohydrate intake, the carbon skeleton of amino acids may be used to s Continue reading >>
Carbohydrates, Proteins, Fats, And Blood Sugar
The body uses three main nutrients to function-carbohydrate, protein, and fat. These nutrients are digested into simpler compounds. Carbohydrates are used for energy (glucose). Fats are used for energy after they are broken into fatty acids. Protein can also be used for energy, but the first job is to help with making hormones, muscle, and other proteins. Nutrients needed by the body and what they are used for Type of nutrient Where it is found How it is used Carbohydrate (starches and sugars) Breads Grains Fruits Vegetables Milk and yogurt Foods with sugar Broken down into glucose, used to supply energy to cells. Extra is stored in the liver. Protein Meat Seafood Legumes Nuts and seeds Eggs Milk products Vegetables Broken down into amino acids, used to build muscle and to make other proteins that are essential for the body to function. ADVERTISINGinRead invented by Teads Fat Oils Butter Egg yolks Animal products Broken down into fatty acids to make cell linings and hormones. Extra is stored in fat cells. After a meal, the blood sugar (glucose) level rises as carbohydrate is digested. This signals the beta cells of the pancreas to release insulin into the bloodstream. Insulin helps glucose enter the body's cells to be used for energy. If all the glucose is not needed for energy, some of it is stored in fat cells and in the liver as glycogen. As sugar moves from the blood to the cells, the blood glucose level returns to a normal between-meal range. Several hormones and processes help regulate the blood sugar level and keep it within a certain range (70 mg/dL to 120 mg/dL). When the blood sugar level falls below that range, which may happen between meals, the body has at least three ways of reacting: Cells in the pancreas can release glucagon, a hormone that signals the b 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
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- International Textbook of Diabetes Mellitus, 4th Ed., Excerpt #59: Mechanisms of insulin signal transduction Part 3 of 8
How Sugar, Not Fat, Raises Your Cholesterol
Excess carbohydrates and sugar lead to cholesterol and weight gain, explains Dr. Doni Wilson, which is why balancing blood sugar levels every day is so important. When you go to the doctor and get a cholesterol reading, you may be cautioned against eating high-fat foods. But very little fat from foods becomes cholesterol in your blood. What produces cholesterol is rather the excessive consumption of carbs at any one time. The cholesterol and triglycerides in your bloodstream come not from consuming excess fat, but rather, from consuming excess glucose. I’m not just talking about excess glucose over the course of a week or even a day. I’m talking about what happens when you consume excess glucose in one sitting. Let’s take a closer look at exactly happens when your body gets too many carbs at one particular meal. First, you digest the carb-containing food, breaking it down into the individual glucose molecules that are small enough to cross the cells of your intestinal walls and enter your bloodstream. Because you have eaten too many carbs, you have far too much glucose stuck in your blood. You don’t have enough insulin to move all that glucose into your cells. So what happens to that excess glucose? Some of it is stored in your liver as a substance known as glycogen, to be released when you don’t eat. Harking back to our hunter-gatherer days, our bodies created a backup system to ensure that even if we can’t get any food for a couple of days, we won’t starve to death. The liver can only hold so much glycogen, however. So what about the glucose that doesn’t fit? Your body has three choices: convert the glucose into body fat, which translates into weight gain, most likely around your middle; convert the glucose into lipids (fats), which remain in your bloo Continue reading >>
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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 >>
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 >>