The Ketogenic Diets changes how the body uses energy. The diet provides ample fat which converts into fatty acids and ketones in the liver. This metabolic state is called ketosis, and, is the hallmark of the diet. Ketosis can also be achieved by fasting; both intermittent and prolonged periods without food. While the term ‘fasting’ is used to describe restrictive eating, fasting in this context is defined as a complete restriction of macronutrients long enough to deplete dietary energy and turn to the body’s energy stores of fat. Water must be consumed during fasting in sufficient amounts to help clear toxins from the body.
How the body stores energy
In order to understand how fasting works, it is helpful to review the ways in which the body stores energy. When food is not available to supply current energy needs, the body turns to its stored energy, either in the form of glycogen or fat. Glycogen consists of long chains of glucose derived from carbs which the body stores in the muscle and liver when we overeat carb. For example, if one were to eat a bowl of pasta that contains 500 carb-derived calories, the body’s breaks down these carbs into glucose. If the body only needs 200 calories worth of glucose to meet its immediate energy needs, 300 calories of glucose are stored in the form of glycogen for later use. The adult body can store, on average, 1,500 calories of glycogen in the muscles, and 500 in the liver. Once the body’s glycogen stores have been filled, any excess glucose in the blood is stored as fat. Fat storage occurs when you overeat. There is no upper limit to how much fat a person can store, and it can be stored virtually anywhere in the body. As we look at the two forms of storage side by side, the body preferentially burns glycogen over fat; once glycogen has been depleted, the body turns to fat. As such, one cannot achieve a state of ketosis if his or her body has stored glycogen, as glucose will be produced from stored glycogen.
Fasting for ketosis
As stated above, when macronutrients are completely restricted, the body sources energy from its own stores. Glycogen gets burned first, then fat. If one is following a typical western diet, where the majority of calories are coming from carb-centric meals per day, a fasted state is rarely achieved, and glycogen levels are rarely depleted. As such, the body seldom, if ever, switches to a fat-utilizing mode, and is therefore not efficient at burning fat for fuel. Moreover, the presence of insulin, a hormone that transfers glucose from blood to cells, is triggered by the consumption of carbs. This prevents lipolysis, which is the breakdown of body fat into useful energy. Being completely dependent on glucose to maintain optimal energy levels requires frequent feedings, and our hunger/satiety hormones ensure these needs are met. These hunger hormones are called Leptin and Ghrelin; Leptin signals satiety, and its release decreases an individual’s appetite. Ghrelin, on the other hand, signals hunger, increasing and individual’s appetite. A high carb diet is thought to increase levels of Ghrelin in relation to Leptin, while a fasting or a Ketogenic Diet seems to balance this signaling system.
The act of fasting shifts the body into a fat-burning mode. Fasting forces the body to first use stored glycogen, followed by fat for energy. Similar to a Ketogenic Diet, fat is being broken down into fatty acids and ketones, a state of ketosis is achieved. If one’s glycogen reserves are filled to capacity, it can take between 2-4 days of fasting to achieve ketosis. This prolonged fasting period can be difficult both physically and mentally. You should consult a medical professional prior to attempting a fast of greater than 24 hours without food. Prolonged fasting has been utilized for thousands of years, dating back to Hippocrates era, for the treatment of epilepsy. Since prolonged fasting is not sustainable over the long term, another form of fasting has been developed that offers a similar metabolic transition, called intermittent fasting. Simply put, intermittent fasting reduces the window of time one eats during the day. A typical eating window for someone practicing intermittent fasting is between 6-12 hours, compared to 16-18 hours for someone practicing a typical western style of eating. When the eating window is shortened, the body is forced to access stored energy more often. When coupled with a Ketogenic Diet, intermittent fasting can optimize levels of ketosis, as well as reduce the time it takes for the individual to become efficient at utilizing fat as their main source of fuel. An important added benefit of fasting is that it can improve the health of our gastrointestinal tract.
What is the Ketogenic Diet?
The Ketogenic Diet, also referred to as the ketosis diet, or Keto for short, is a way of eating that mimics the effects of fasting. By consuming a diet rich in quality fats, adequate in protein, and low in net carbohydrates (total carbs minus fiber), the body’s metabolism begins to utilize fat as its main source of fuel, rather than carbs. This shift has profound effects on metabolism for both the sick and healthy alike. The diet shows promise for improving or reversing many neurological conditions and metabolic disorders. For the healthy, the diet represents a tool for preventing chronic disease, as well as optimizing cognition and body composition (i.e. fat loss).
What is Ketosis?
The term ketosis refers to a byproduct of the breakdown of fat into energy, called ketone bodies, or ketones for short. This fat can be derived directly from the food we eat, or adipose tissue stored throughout your body (otherwise known as body fat). Ketones are used directly by the body to power itself. This breakdown of fat into useful energy is similar to the process that dietary carbohydrates undergo in producing glucose to fuel the body. In other words, ketones are to fat what glucose is to carbohydrates. Ketosis is defined as having blood ketone levels > 0.5 millimolar/L.
What are the benefits of Ketosis?
Achieving a state of ketosis can have many benefits from treating chronic illnesses to optimizing performance. While the benefits are well documented, the underlying mechanism of action is not entirely known. The diet seems to enhance the ability of mitochondria, the power plants of our cells, to deliver our bodies’ energy needs in a manner that reduces inflammation and oxidative stress. Through optimizing the way our body uses energy, we fortify our bodies’ ability to take on the ever-growing stressors of our modern way of living.
How do I get into Ketosis?
There are two methods to make the metabolic shift from using glucose to ketones as your main source of energy.
Fasting – the method of complete cessation of caloric intake for a prolonged period of time has been used to treat disease as far back as 400 B.C. when Hippocrates, the Father of Modern Medicine, employed the method for a myriad of ailments. Though this should be done under medical supervision,fasting is a safe, effective (and, some would say, the easiest) way to get into ketosis, quickly. For the average adult, a 48-hour fast will generally result in ketosis. After this fast, adopting a Ketogenic Diet will allow you to stay in ketosis. We recommend starting the fast at least 3 hours before bedtime on the first day, and eating at the same time 2 days later. While fasting means many things to many people, we define it here as the total restriction of macronutrients. We recommend boosting water consumption in order to avoid dehydration, and many find black coffee or plain tea to help maintain focus and performance during the fast. Children go into ketosis much faster and therefore can be started on the diet without fasting and should also have close medical monitoring.
Diet – adopting a high fat, moderate protein, and low net-carb diet, will result in ketosis, and will take 2-3 weeks to achieve a consistent state, as defined above. We will go into diet options below, but you can also link to them here. During this period of transition, one can experience flu-like symptoms and tiredness. There can also be emotional unease related to longing for high-carb foods. Working with an experienced Ketogenic Specialist can help to minimize these effects.
Getting Started
Do you think the intermittent fasting is right for you? Talk to your doctor before adopting a fasting regimen, or connect with one of our qualified diet professionals to determine a course of action that is right for you. The links below provide access to diet professionals and hospitals with expertise in ketogenic therapies.