When it comes to entering into any major lifestyle change, the best way to be successful is to take the time to investigate the facts and arm yourself with all the information you need. That’s especially true when it comes to low-carb diets. The arguments, myths, misconceptions, and false ideas that surround dietary ketosis can easily overshadow the science if you don’t know how to separate biological truth from personal opinion and marketing.
To help with that process, this beginner’s guide to dietary ketosis explains the basic principles of ketosis. It reveals how restricting carbohydrates improves your chances for fat loss, and tells you exactly what you need to know about metabolism to get started on the road to a new and better you.
Restricting Calories Ignores Metabolic Defects
Standard weight-loss solutions focus on portion control. They ask you to reduce your fat intake, to conserve calories, and to up your activity. If you are free from metabolic problems, these changes can work well, but if you have insulin resistance, diabetes, cholesterol issues, fatty liver or inherited defects in the way your body secrets and uses insulin, they might not. Reducing fat and calories doesn’t address the metabolic defects associated with elevated insulin and blood glucose levels.
How a Glucose Metabolism Works
Dr. Michael R. Eades, author of The Protein Power LifePlan, in a blog post entitled "Metabolism and Ketosis," explains that the body fights for homeostasis. It loves balance and will keep your blood sugar within a tight margin of safety. When blood glucose dips below that narrow range or rises above it after you eat, hormonal responses move to correct the imbalance as soon as possible.
One of these corrective hormones is insulin. The presence of insulin ushers the glucose into your body cells where it can be used for fuel or stored for later use. When blood glucose falls too low, other stress hormones such as adrenaline encourage the liver to use its glycogen stores to correct the problem.
Your body can actually use four main sources of fuel. Which type it chooses, depends upon its immediate needs. When glucose is available, the body generally uses glucose first. The only exception to that is alcohol. For that reason, many people believe the body prefers glucose over other sources, but Lyle McDonald, author of The Ketogenic Diet says that glucose is simply easier because it doesn’t have to be broken down and converted into something else before it can be used.
Although parts of the brain, red blood cells, and some kidney cells lack the mitochondria needed to burn non-glucose forms of fuel, McDonald assures his readers that throughout a 24-hour period, the body switches between using glucose, essential fatty acids, protein, and ketone bodies. There isn’t a single fuel the body depends on. It simply chooses the most efficient method from its available supply.
Glucose comes from carbohydrates. Since most people eat a large amount of carbohydrates, glucose is often the major source of fuel, but other sources can be used when glucose isn’t available.
Of concern to low-carb dieters is what happens when you supply the body with more glucose (or carbohydrates) than it needs. When that happens, the excess glucose is shipped to the liver, so it can be converted into glycogen – the storage form of carbohydrates. Between your liver and muscles, glycogen stores hold about 300 to 400 grams of carbohydrates.
Excess glucose is not converted into triglycerides and stored as body fat unless your glycogen stores are full.
For that reason, many don’t perceive high carbohydrate diets to be a problem. That’s true if you keep your daily calories within your individual maintenance level. The body will convert a portion of the protein you eat to glucose and pull from your body fat stores as needed to make up for any lack of glycogen. Blood glucose levels stay steady and the body is happy.
The problem arises when you eat more grains, starches, and sugars than your glycogen storage can hold. When you consistently go over your storage capacity, the result is overweight and obesity.
Elevated Insulin Prevents Body Fat Mobilization
When your metabolism is defective, the pancreas has problems secreting enough insulin, or your body cells don’t recognize the insulin the pancreas makes. Both types of defects result in elevated blood glucose levels, which can then cause a variety of complications and neurological problems. If you are overweight, some degree of insulin resistance is at play because while insulin levels are elevated, Dr. Eades says that body fat stores cannot be accessed.
The presence of insulin is what signals the liver that glucose is available, but glucose isn’t the only substance that finds itself shuttled into body cells when insulin is around. All of the fats in your bloodstream and the fats in the food you just ate are also sent to the liver to be stored. Since body fat stores cannot be mobilized when insulin is high, Dr. Eades believes this newly stored fat becomes stuck inside your fat cells even when glycogen stores are low.
This is not a problem under normal metabolic conditions because insulin levels will fall as soon as the glucose is taken care of, but when the body doesn’t respond to insulin correctly or cannot make enough to handle the amount of glucose currently in the blood, both blood glucose and insulin levels can stay elevated for hours. Regardless of the number of calories eaten, body fat stores remain locked up. This is why insulin insufficiency in Type 1 diabetics causes weight loss rather than weight gain.
A Ketogentic Diet Focuses on Metabolic Defects
The focus of a low-carb diet is on reducing insulin levels and stabilizing blood glucose rather than zeroing in on the number of daily calories you eat. That doesn’t mean that calories do not count. It simply means that initially, whether you're following the Atkins Diet, The Protein Power LifePlan, or even The South Beach Diet, the goal is to correct your metabolic defects.
By correcting metabolic irregularities, your body fat stores will become more available for fuel. Later on, calories can be reduced if necessary.
With easy body fat availability, your metabolism switches from predominantly burning glucose to fatty acids. This fatty-acid metabolism drastically lowers the amount of triglycerides in the blood and raises your level of HDL cholesterol to a healthy ratio. To do that, carbohydrates in the diet must be restricted.
How drastically you have to curtail them depends upon your degree of carbohydrate sensitivity and the low-carb program you’ve chosen to follow, but most individuals find they have to limit themselves to somewhere around 20 to 60 grams of carbohydrates per day in order to enter the state of Ketosis. However, carbohydrate tolerance is extremely individual as the follow video explains.
How Many Carbs Can You Eat and Stay in Ketosis?
How You Go Into Ketosis
The reduction of available glucose from carbohydrate restriction causes the liver to use its glycogen supplies to keep your blood sugar level steady. For every molecule of glycogen stored, the body also stores 3 to 4 molecules of water, so while the body is using its glycogen stores, you’ll also shed that excess water.
Glycogen storage depletion takes about a day. After it depletes to about half full, the liver begins using dietary fat to fuel the conversion of protein to glucose. If your dietary fat isn’t high enough, the liver will also begin pulling triglycerides from your body fat stores. That’s what you want it to do. In fact, Dr. Eades cautions low-carb dieters not to eat so much fat that your body doesn’t have a reason to use your fat stores for fuel. Once the body begins using its fat stores for fuel, you are in Ketosis.
This process is known as Gluconeogenesis and is used to supply the brain, red blood cells, bone marrow, and kidneys with the glucose they need. Although water losses during the first week of a low-carb diet can be huge, once the body goes into the state of Ketosis, most weight loss from that point on comes from body fat and will therefore slow down to a normal pace.
Ketones Are a By-Product of Fat Mobilization
When triglycerides are broken down, their glycerol molecule can be used for glucose, but there is only a very small amount of glycerol attached to a fatty acid. Initially, triglycerides mostly fuel the liver’s activities. Later on, the body will use them to fuel most of your systemic functions and energy needs, but in the very beginning of a carbohydrate-restricted diet, the body will use mostly ketones.
Ketone bodies are a by-product that occurs whenever triglycerides are broken down, so Lyle McDonald says they are not exclusive to a low-carb diet. Any diet that causes fat loss produces ketones. In fact, ketones occur in everyone after an overnight fast or on any particular day when a much lower level of carbohydrate is consumed.
When carbohydrate is in short supply consistently, however, the liver converts more protein into fuel, which results in more ketones. As ketones begin to back up slightly in the bloodstream, their higher presence is called “getting into Ketosis.”
How Are Ketones Used?
Ketones can be used for fuel by the muscles, heart, and the portions of the brain that have mitochondria. In fact, Dr. Eades states that ketone bodies are the heart’s preferred fuel source. They help the heart work more efficiently. Other body tissues can use fatty acids.
Only a few, such as the brain, actually require glucose, but this essential glucose can be made from dietary protein. Lyle McDonald stresses that gluconeogenesis does not come from muscle unless you do not eat enough protein, although muscle is the way the body stores excess dietary proteins. On the other hand, eating too much protein can interfere with going into Ketosis because the liver can use that protein for energy rather than making the metabolic switch. This seems to occur if your insulin levels drop too low.
Dietary Ketosis (or Nutritional Ketosis) is Not Ketoacidosis
One of the major arguments against using a low-carb diet is that elevated ketones in the blood are dangerous. This argument comes from a misunderstanding about Ketoacidosis and what causes it.
Ketoacidosis occurs when your blood glucose level is too high because your insulin levels are too low. This happens in Type 1 Diabetics who are unable to make enough insulin to correct the problem. Since Type 1 Diabetics cannot produce insulin, high levels of glucose accompanied by the dehydration that occurs as the body attempts to rid itself of excess sugars can cause a serious, life-threatening situation because the body becomes too acidic.
Diabetic Ketoacidosis doesn’t happen with dietary ketosis because the body’s backup system simply secretes insulin whenever your ketone level goes too high. For most dieters, this occurs around 5 or 6 mmol/L or less. With insulin elevated, your body-fat stores will temporarily lock down until the body uses the excess ketone bodies and they fall to a more manageable level.
For the average low-carb dieter, the level of ketones in the blood is about 1 to 3 mmol/L. In comparison, for Diabetic Ketoacidosis to occur, that level soars to a whopping 25 mmol/L or more in a matter of hours. This never occurs with dietary Ketosis.
Adapting to the State of Ketosis
There are three types of ketones produced by the body: acetoacetate, beta-hydroxybutynate, and acetate. Initially, both acetoacetate and beta-hydroxybutynate are used to fuel your muscles, but the brain doesn’t use acetoacetate ketone bodies very well, so most of them are dumped into the urine. When you use urine-testing strips such as Ketostix, acetoacetate ketones are the type of ketone bodies you’re testing for. This is a temporary stage and means the body is beginning to adapt to the metabolic changes.
After you’ve been low carbing for a few weeks, the muscles begin converting acetoacetate ketones into beta-hydroxybutynate, the ketones the brain uses. Your muscles and other body tissues switch to using fatty acids instead in order to save the available ketones for the brain, kidney, red blood cells, and heart. In addition, the kidneys begin to down-regulate the amount of ketones it disposes of. The longer you stay in Ketosis, the fewer ketone bodies the kidneys will dump into the urine.
For most folks, the metabolic advantage associated with spilled ketones at the beginning of a low-carb diet completely stops. For others, the process continues but is less noticeable. How quickly this happens depends on whether the body is new to dietary Ketosis or whether you have used the pathway several times before. The more often the body goes into Ketosis, the better it gets at using Ketones for fuel.
In fact, Dr. Atkins in his book, Dr. Atkins’ New Diet Revolution, cautions dieters not to abuse his Induction Plan. For those who consistently move back-and-forth between weight loss and Induction, or maintenance and Induction, Dr. Atkins says, “It will probably backfire in more ways than one. It’s likely that your metabolism will adapt at a certain point – in a sense, develop a tolerance.”
People who yo-yo find that Induction doesn’t work as well as it once did. They no longer begin a low-carb diet with an advantage over other diets. This loss of metabolic advantage doesn’t mean the diet won’t work, or has stopped working. It means you have adapted to the state of Ketosis. If you’ve been following a low-carb diet for several weeks now, your body has switched from predominantly using glucose for fuel to efficiently burning fatty acids and ketones instead. When that happens, a calorie deficit is essential.