Our bodies have two sources of fuel - the calories that we eat, and fat stored in our bodies. When we don’t eat, the body then turns to stored fat for fuel, resulting in fat loss. The body is either storing food energy (feasting) or we are burning it (fasting). When fasting and feasting work together in harmony, there is generally no weight gain. Sounds simple right?
The body can pull from three different kinds of materials to create energy: protein, carbohydrates, and fat stores. All three provide energy for the body but at different rates and through different pathways. The body only has a small amount of glycogen (stored sugar) that it can pull from. Once this has been emptied, it moves right on over to protein and lipid. However, it is more efficient to use lipid (or fat mass) than protein because there is a lot more energy in fat mass than in muscle mass. Sound surprising? So, for the most part, the body will begin to burn fat once all carbohydrates have been used up. At this moment when the body is burning only fat, we believe that it is truly in the fasting state; this is just around 48 hours after the last meal. The way we see the body burning fat is actually through the unique molecules called ketone bodies. As fat burning increases, so do ketone bodies. We call this state “ketosis”. If the body is left in this state for too long, which is to say if the body continues to not have nutrition coming in, then the body will begin to starve. If left in starvation, then the body will eventually become malnourished.
In simple terms, fasting is the omission of food. However, it truly is much more than just that! What are the benefits of fasting? What determines the fasting state is actually a combination and quantity of the specific macro and micronutrients of the foods we eat. Luckily, there is more than one way to fast, but there is only one that has been shown to induce rejuvenation and regeneration.
TRF is a form of intake restriction that is specifically focused on when and how long eating occurs rather than macronutrients. This type of fasting is based on the theory that our ancestors likely fed during daylight with limited resources and fasted during the night. Interestingly, this is controlled by what we call the circadian system. The circadian system oscillates every ~24 hours in a rhythm that enables organisms to respond to the light-dark cycle, which coincides with food accessibility. Today, this system has been disrupted due to long work hours, artificial light exposure, and haphazard eating behavior. To get back control of this system, we can mimic the natural circadian pattern by restricting feeding to a certain period of time.
Intermittent fasting is a form of fasting where the individual will fast for an interval of time, usually no more than 48hrs, and then eat normally for the remaining period of time throughout the week. The most common example of this is known as the “5:2” diet, where the individual restricts calories for 2 days, consecutive or not, and then eats normally for the remaining 5 days. Other daily fast to eat schedules include 14:10 (fast for 14 hours, then eat all your calories within 10 hours), 20:4, and 16:8; the 16:8 method is the most common because it fits into most modern working lifestyles in the US. This fasting method has been linked to a range of potential health benefits, including short-term increases in human growth hormone (HGH) and changes in gene expression. It is also said that other benefits of intermittent fasting include helping those who have been diagnosed with Type 2 diabetes, because it helps manage your sugar intake and lower your blood glucose. Many people choose to fast when they have diabetes and especially when they want to eventually stop taking medicine for it.
Fasting as a way to regain or refocus spirituality is common in many religions. That’s right, Jesus was into a fast. Religions and philosophies that practice fasting include: Buddhism, Christianity, Islam, Judaism, Taoism, Jainism, and Hinduism. Fasting can last for just a few hours or even a few weeks, usually with practitioners eating at night. Different religions may fast differently or at different times. For example, within Christianity, there are several different denominations that fast at different times. Catholics do not eat meat on Fridays during Lent, while Coptic Christians, the main form of Christianity in Egypt, fast for different durations for a total of 210 days throughout the year. They have eight main fasts, and each lasts for a different duration and restricts the diet in a unique way. For others, fasting is meant to bring worshippers closer to God through steady remembrance, reflection, and sacrifice. Daily fasting, combined with five daily prayers and extended evening prayers, challenges worshippers to focus on their actions, deeds, and thoughts, rather than on material desires and instant gratification.
Fasting is a reset for the mind, body and soul. Muslims are expected to show self-control and deeper spirituality during Ramadan. It's also a month of gratitude. By abstaining from food and water during the day, the faithful are reminded of those less fortunate. Each night during Ramadan, mosques and aid organizations set up tents and tables to serve free evening meals for the poor.
Many of you will have heard of the keto diet which is a low-carb, high-fat diet. Ketosis lowers blood sugar and insulin levels and shifts the body’s metabolism away from carbs and towards fat and ketones. A ketogenic diet is an effective way to lose weight and lower risk factors for disease. There are several versions of the keto diet. The standard ketogenic diet (SKD) is the most researched and most recommended. This is a very low-carb, moderate-protein, and high-fat diet. It typically contains 75% fat, 20% protein, and only 5% carbs. The diet can actually be so satiating that you can lose weight without counting calories or obsessing over your food intake.
There is no single way to fast, meaning that the duration of your fasted state is up to you. There are different methods that exist. For example, the 5:2 pattern says to restrict your calorie intake for two days per week (500 calories per day for women and 600 for men). The 6:1 pattern is similar to the 5:2, but there’s only one day of reduced calorie intake instead of two. The “Eat Stop Eat” method is a 24-hour complete fast that you do 1–2 times per week. Last but not least, the 16:8 pattern involves only consuming food in an eight-hour window and fasting for 16 hours a day, every day of the week.
Unlike food, when you consume apple cider vinegar or coffee, for example, the fast is not broken, and the benefits of fasting can actually be enhanced. Both coffee and apple cider vinegar promote AMP-activated kinase (AMPK) within the body. AMPK is an enzyme that plays a role in cellular energy homeostasis by activating glucose and fatty acid uptake and oxidation when cellular energy is low. Many researchers studying the benefits of intermittent fasting in conjunction with consuming non-food products like apple cider vinegar believe that AMPK activations are extended, furthering the benefit of intermittent fasting. There are many vitamins in apple cider vinegar including vitamins B1, B2, B6, biotin, folic acid, niacin, pantothenic acid, and vitamin C. It also contains minerals such as calcium, iron, magnesium, phosphorus, potassium, and sodium. Together, these minerals and vitamins provide support to the body to strengthen the nervous and immune systems, while supporting overall health and body optimization.
Putting a slice or two of lemon, cucumber, or mint in your water doesn’t have enough of an effect on your blood sugar or insulin levels to break your fast. Sure, lemons and other citrus products do contain calories in the form of fructose, which does stimulate the liver to break a fasted state, but eating and drinking aren’t treated the same in the digestive process. The most important thing to remember is to listen to your body; most of the benefits of fasting can still be achieved even with breaking the fast up to 100-150 calories. Add a splash of milk to your coffee or snack on some vegetables - there are no absolute rules when it comes to what’s right for your body.
Generally, you can continue taking supplements and still get the fat-burning benefits of an intermittent fast. However, first consider that if you’re only consuming water and/or black coffee while fasting, some vitamins (like B vitamins and zinc) can make you feel nauseous on an empty stomach. If you are going to take any of these, you probably want to save them for your eating windows (and if you’re not sure how they’ll react on an empty stomach, definitely wait). It's important to be mindful of your supplements because some of them can affect your body’s function during your fast.
For example, they can:
If you’re taking a vitamin supplement, consider this - vitamins break down into two categories:
Fat-soluble: These vitamins should be eaten with fat-containing food in order for your body to absorb them. They include vitamin A, vitamin D, vitamin E, and vitamin K. The body stores fat-soluble vitamins in the liver and body fat. Taking these in windows when you aren’t consuming food with fat in it means you’re less likely to absorb them, so there’s no real point. While fasting for less than 5 days, you’ll be burning your own body fat and getting vitamins that way.
Water-soluble: These vitamins are not stored in your body but are excreted during the day if you drink liquids. They include: B-complex vitamins, like B1, B2, B3, etc, folic acid, vitamin C, and many others. You can take these on an empty stomach, but again, they might upset it. If you’re doing short term fasting over the course of a few days, you aren’t likely to deplete enough of these to affect your health negatively. You only need to consider supplementing if you’re fasting for more than a week.
For those who are supplementing during fasting, it's suggested to not take in too much vitamin C and vitamin E. Too much vitamin C can cause kidney stones and too much vitamin E can cause blood-clotting problems. L-tyrosine is one alternative because it may help you feel stronger and mentally sharper while fasting. You can also take this on an empty stomach.
It is said that the longer you fast, the more likely you are to need supplementation, but most importantly, pay attention to how you feel and make sure your nutritionist or health professional is aware of how you are fasting. When you do eat, make sure to eat a variety of foods, or implement a diet like the mediterranean diet, which is associated with reduced risk factors in a number of health conditions like type 2 diabetes and blood pressure.
Figure out when your feeding window and fasting periods will be.
There are a few different ways to fast. Some of the most popular ways to start intermittent fasting are the following:
Starting a fast whether it’s a full day or just a few hours can be hard. The key to being successful is to listen to your body. Start small and if you start to feel any negative side effects, pay attention to that and eat something if you feel the need.
Eat Fibrous and Fatty Foods
Foods that contain high quality of fiber content are more filling and if paired with foods that are higher in healthy fats, they will keep you fuller longer. Examples include oats, peanut butter, and protein powder, or you can make smoothies out of all of them.
Don’t restrict calories during the eating period
The purpose of the eating period is to give your body the energy it needs to function. It can be tempting to restrict calories during this eating period but that can derail your progress and cause your body to crave more food and break your fast before you’re ready.
Don’t binge-eat during the eating period
The opposite of restricting calories is binging. This can also be detrimental because you will increase calorie consumption and slow down the benefits of fasting altogether. If eating disorders have been an issue in the past, fasting might not be the right nutrition plan for you.
Don’t overexert your body while fasting
When you’re fasting, your body is lacking the normal amount of energy you typically get from your daily meals. While it’s okay to workout as you normally would, it’s important to not burn out your body to the point of exhaustion. The key to intermittent fasting is to be mindful of what you’re eating and when. Listen to your body and give yourself a good chance of succeeding by starting with a realistic ratio of fasting to eating windows.
Some people choose to take supplements while fasting to ensure adequate vitamin and mineral intake. Fasting too frequently could lead to nutrient deficiencies if your diet is already low in vitamins and minerals.
Focus on replenishing your electrolytes and keep up any vitamins you already take if possible. The longer you fast, the more likely you are to need supplementation. Most importantly, if you want to have a successful and healthy fast, pay attention to how you feel and make sure your doctor knows you’re fasting.
