What is intermittent Fasting?
Intermittent fasting is one of the most potent ways to get in shape and enhance your body, mind, and life. But what exactly do I mean by intermittent fasting?
Simply, intermittent fasting is not eating for a set period, the fasting window, then consuming all of your daily calories during another set period, the eating window. For example, fasting (not eating) for sixteen hours of the day, then eating your daily meals during that remaining eight-hour window. It’s about when you eat, not what you eat. Intermittent fasting meshes with any eating approach: keto, low-carb, paleo, vegan, vegetarian, whatever. In a nutshell, Intermittent fasting is a meal-timing plan, not a diet. That’s it.
How can something so straightforward as not eating for a set period bring about a fantastic array of benefits and transform your health? Fasting flips a metabolic switch that completely changes the way your body works. Flipping the controller alters the type of fuel the body uses—instead of running on glucose, the body starts running on fat—and sparks a host of physiological changes that go way beyond body composition to boost cellular rejuvenation, heart health, and brain function.1 Fasting is not about restricting calories; it’s about revealing a completely different side of our bodies, one we would never get to utilize unless we purposefully accessed it—time to get excited about how your body works.
| Intermittent Fasting IS | Intermittent Fasting IS NOT |
|---|---|
| About flipping the metabolic switch to burn fat for fuel and optimizing the way your body works | A diet (what you eat) |
| A meal-timing plan (when you eat) | Complicated (unless you want it to be!) |
| A set period of time per day when you do not eat followed by a finite period of time when you do eat | Expensive |
| Workable with any dietary eating style | Rigid or inflexible |
When you eat, your body goes into storage mode. Sure, some food we eat is converted into energy that’s used right away, but most of us eat more than we need to, and we store what we don’t need.
How Carbs, Fats, and Proteins Impact Your Fasting Journey
Three macronutrients—carbohydrates, fat, and protein—are required in large amounts to provide the body with enough energy to function optimally. Each macronutrient has a unique part to play in the process.
Carbohydrates: Carbs are a quick and easily used energy source, which is why your body loves them. When you eat carbs, your body breaks them down immediately into a simple sugar called glucose, also often called blood sugar. Glucose can be used instantly by all cells to power up, and any unused glucose is stored for later. There are two ways glucose is stored: First, it is stored as glycogen in the muscles and liver. Then, when the liver has reached its glycogen limit, excess glucose is packed away as fat in the liver and in adipose (fat) cells throughout the body. There is no limit to how much glucose can be reserved as fat.
Fat: Food’s primary fats are triglycerides, three fatty acids, and a glycerol backbone. It takes a long time to break down and digest fats, so eating fat keeps us satisfied longer. These complex fat molecules provide the densest energy for your body, generating nine calories per fat gram compared to four calories in every carbohydrate or protein gram. Still, because the body prefers glucose, most fat isn’t used immediately for energy. Instead, excess fat is deposited in adipose cells.
Protein: Made of small units called amino acids, protein is critical for the growth and repair of virtually every cell and tissue in our bodies, from muscles and bones to skin and hair. Unlike carbs and fats, protein isn’t a primary go-to energy source, though, under certain circumstances, it can be converted to glucose. The body can’t store excess protein, so any extra protein eaten is converted to glucose and stored as glycogen or fat.
Insulin, made by the pancreas, is the hormone to watch for intermittent fasting. Its level in our bodies goes up when we eat, and a high insulin level keeps the body in fat-storage mode. Its level in our bodies goes down when we fast, and a low insulin level allows us to use stored body fat for fuel.
Ingesting any of these three macronutrients signals to your body that it’s time to use the food for energy immediately or, most likely, save it for later. One hormone is central to accomplishing both of these tasks: insulin.
Eating any food triggers an insulin response. This may surprise you: It’s not just carbs that raise insulin levels. Protein and fat do, too. Although insulin is most well-known for shuttling glucose into cells for immediate use, it does the same for fat and amino acids.
But insulin isn’t called an anabolic, or storage, hormone for nothing—any leftover carbs, fat, or glucose are stored as glycogen and fat by insulin. Insulin also keeps fat from being used as energy. Why start burning stored fat for fuel when food (more fuel) is coming in? High insulin levels promote fat storage and prevent fat burning.
When we eat, and insulin levels remain high, we stay in fat-storage mode and don’t tap into our energy reserves for fuel. The body runs on the incoming food (fuel) and packs away the leftovers—and unwanted pounds.
How Does Intermittent Fasting Work
Could you start using some of that fat for fuel instead? That’s precisely what happens when we fast.
When we are fasting, our bodies enter burning mode. Insulin levels decrease, so the body taps into glycogen and stores body fat for fuel. When your body senses less energy, it recognizes the need to flip the metabolic switch and utilize its stored fuel. That energy sensor is an adenosine monophosphate-activated protein kinase (AMPK) enzyme. When AMPK is triggered, the low-fuel light in your car tells you to get gas. That fuel light tells the brain that no food is coming in, so it’s time to start burning stored energy. When AMPK is activated, the move from fat-storage to fat-burning mode proceeds like this:
1. TAPPING INTO GLYCOGEN STORES. Once you stop eating and your body uses all the glucose in your bloodstream for fuel, insulin levels drop, and the body starts burning its fuel reserves. First up is glycogen, excess glucose stored in the liver.
2. BURNING FAT AND MAKING NEW GLUCOSE. With no new glucose coming in (because you aren’t eating) and glycogen stores depleted, your body starts looking for other energy sources. Triglycerides, the stored form of fat, are broken down into fatty acids released directly into the bloodstream. Just about every cell in the body can use fatty acids for fuel. Major exceptions to this rule are red blood cells and brain cells, which rely on glucose. To supply these cells and maintain steady blood sugar levels—we still need stable blood sugar during a fast, or we risk confusion, seizures, and death from hypoglycemia—the body starts manufacturing glucose from sources other than carbohydrates.
In gluconeogenesis, glycerol from fat and amino acids from protein are turned into glucose in the liver.
When gluconeogenesis ramps up to produce glucose, the body also starts making another energy source: ketones. When the liver breaks down fat, it uses glycerol for gluconeogenesis and converts the remaining fatty acids to ketones, a very efficient fuel source that can power the brain.
3. RUNNING ON KETONES. Trying to run the body on glucose via gluconeogenesis is very costly. So, the body shifts, turning to ketones as the dominant energy source. Gluconeogenesis continues to happen—you still need glucose to survive—but ketones are now the body’s primary fuel and are burned in ketosis. Because making ketones relies on fatty acids, more ketone production means you use more fat for fuel. In this energy-burning phase, ketone production has nothing to do with being on a ketogenic diet and everything to do with your body switching to an alternative fuel source during a fast.
In addition to lowering insulin, fasting causes changes to several other hormones that promote fat burning. These hormones are called counter-regulatory hormones because they run counter to insulin. These hormone levels increase when insulin levels decrease, and vice versa.
High epinephrine (adrenaline) and norepinephrine (noradrenaline). Fasting puts your body under stress, which causes a significant surge in the catecholamines epinephrine and norepinephrine. These two hormones are the main drivers of fat burning and rev it up significantly.
High human growth hormone. Secreted by the pituitary gland, the human growth hormone preserves muscle, helps our bodies utilize fats better to save and spare our muscles, and prevents blood sugar levels from dropping too much by stimulating the liver to produce more glucose.
High cortisol. This so-called “stress hormone” is not the enemy. It’s a friend when you’re in a fasted state. You need to know that Cortisol plays a dual role in fat. In the presence of food and insulin, cortisol promotes fat storage. But fasting is a different ball game. Food is out of the equation, and insulin is low. Now, spikes of cortisol-free fat are stored in the body to be burned for energy. Fasting leverages cortisol to your advantage. Remember, cortisol levels naturally fluctuate, starting higher in the morning and falling throughout the day. Fasting doesn’t chronically elevate our cortisol levels; it makes the surges higher.
Regarding fasting, the sooner we tap into our energy reserves, the better. The goal of fasting is to deplete glycogen stores and move into fat-burning mode as early in our fasting window as possible.
Many myths and pieces of misinformation are circulating about intermittent fasting. Let’s clear the air on some of the most frequently asked questions.
Is intermittent Fasting Right For You?
I’m over age fifty.
You are young enough for intermittent fasting. Age alone (unless you are under 18, which means you should only fast once your body has fully developed) is not the determining factor of how safe or effective intermittent fasting will be for you. Underlying medical conditions or medications may be an issue (see following entries), and it is a good idea to check with your healthcare provider before starting a fasting regimen. You should take steps to ensure you are fasting healthily and effectively. Visit FastingIsEasy.com for more resources on how to fast safely over age fifty.
Ease into it. Over age forty, we start to lose metabolic flexibility, the capacity to adapt quickly to shifts in our diet. Similarly, your cells will take a little longer to use stored energy substrates, such as fat.
Eat adequate protein. As we age, we start to lose muscle mass naturally. It would help to have sufficient protein on fasting and nonfasting days to offset this loss. Aim for between two and three grams of protein per kilogram of body weight.
Support with supplements. Supplements, such as vitamin D to further protect you from sarcopenia and age-related muscle loss, and coenzyme Q10 to support the ruthlessly efficient utilization of nutrients, will be an essential part of your lifestyle.
I have diabetes.
(If you have diabetes or any condition, ask your doctor before beginning.) In some, intermittent fasting has been shown to improve insulin sensitivity. However, you must monitor your blood sugar and work closely with your health care provider to ensure your insulin. Any other medications are correctly tuned to ensure your blood sugar remains in a steady and proper range during your fasting and eating periods.
| Fast with Caution If You . . . | Avoid Intermittent Fasting If You Are . . . |
|---|---|
| Have certain medical conditions (ask your doctor) | Under age 18 |
| Take medications | Pregnant |
| Have a history of disordered eating | Breastfeeding |
| Severely malnourished or underweight, with a body mass index (BMI) of less than 18.5 |
I have other medical conditions.
Please speak to your healthcare provider before fasting to ensure it is safe. Your healthcare provider’s advice is essential if you take medication, as some may be less effective or cause side effects if not taken with food.
I’m pregnant.
Fasting is not recommended during pregnancy. There isn’t enough research on fasting’s effect on pregnancy or the long-term effects that could appear later in the baby’s life. Fasting may make it harder for you to get the proper nutrients you and your baby need and alter your hormone levels unpredictably. Why gamble?
I’m breastfeeding.
You are fasting while breastfeeding is not recommended. If you’re in any way nutrient deficient, your baby will be, too, and your milk supply may decrease. To avoid compromising your child’s development, wait until your baby is weaned to start intermittent fasting.
I have a history of disordered eating.
Intermittent fasting should support a healthy lifestyle and quality of life. It is not a form of disordered eating, but if you find yourself so focused on fasting that your quality of life suffers or you develop a problematic relationship with food, such as severely restricting it, binge-eating, or guilt-driven purging, speak to a health care professional or counselor who can help you safely incorporate intermittent fasting into your lifestyle or find better ways to reach your health and wellness goals.
Will I lose muscle?
Fasting promotes muscle preservation, and if you do the right things after a fast, such as eating adequate protein and performing resistance training, it can even help build higher-quality muscle. Although some protein is broken down during fasting, much is reallocated, not “lost.” In one eight-week study, men ate and trained the same way, but one group fasted for sixteen hours per day, whereas the other group did not. Both groups maintained all their muscle, but the fasting group lost significantly more fat. Intermittent fasting does double duty, saving muscle and shedding body fat.
Your body has different needs while fasting. For example, it doesn’t need amino acids and protein to build digestive enzymes during a fast. You’re not eating, so why would you need digestive enzymes? Instead, those amino acids and proteins can be reallocated where required, such as supporting muscle preservation. So, it’s all about reallocation.
We know this reallocation happens because autophagy, or the body’s way of clearing out the old or damaged parts of cells and recycling them, increases. Autophagy acts like Robin Hood, taking unnecessary or dysfunctional components from no longer needed cells, breaking them down, and supplying them to new areas of the body that could use a little extra support.
While autophagy works on reallocation, human growth hormone makes sure we’re not breaking down protein and that the protein that is broken down gets used in the best possible way. The Journal of Clinical Endocrinology & Metabolism found that, even after a short fast, there was a five-fold increase in human growth hormone, and studies average a three- to five-fold increase.
Researchers tested the protective power of this human growth hormone by giving somatostatin, which blocks growth hormone, to one set of study participants. What happened when their protein levels were checked after a forty-hour fast? There was a 50 percent increase in the amount of protein excreted by the body in the participants whose growth hormone was inhibited compared to the control group. When there was no growth hormone, the protein wasn’t being reallocated; it was being released en masse. Elevated growth hormone levels during a fast help preserve muscle and lean body mass.
What this means is that you don’t lose muscle while fasting. Any protein broken down from muscles is used elsewhere, and by clearing out and replacing the broken-down parts of your cells, you’re setting the stage for better, stronger muscles.
Ketones produced when you’re fasting also preserve muscle. One study found that ketones reduced muscle breakdown by 18 to 41 percent.
Will My Metabolism Slow Down Due To Intermittent Fasting?
Fasting does not slow your metabolism, or basal metabolic rate (BMR), the amount of energy (calories) needed to perform essential bodily functions, such as breathing and circulation, at rest. Studies suggest fasting, instead, has a powerful effect on maintaining metabolism. One study found that twenty-four-hour alternate-day fasting (one-day fasting, one day not fasting) for twenty-two days did not change participants’ metabolic rate, but they did lose weight. I don’t recommend this long-term fasting. Still, these results highlight how fasting does not necessarily lead to a sluggish metabolism, and research suggests it can cause the opposite, revving it up. In one study, the metabolic rate increased on the first three days of a four-day fast.
Your metabolism slows when the body tries to conserve energy. This often happens on calorie-restricting diets as the body responds to energy scarcity by lowering the rate at which it burns calories. During a fast, your body doesn’t need to cut back on energy because it can tap into its fat stores and has all the fuel it needs to keep everything humming. The rise in epinephrine and norepinephrine also stimulates your metabolism.
Is intermittent Fasting Different For Women?
Fasting for women is similar to fasting for men. The basics of how to fast and the benefits you will experience are essentially the same. That said, fasting puts stress on the body. Although stress isn’t inherently wrong and can lead to many positive outcomes, stress can also lead to negative hormonal changes, including reproductive hormones.
Much concern about women fasting relates to the hormone kisspeptin and its role in the menstrual cycle. Kisspeptin is very sensitive to fluctuations in insulin and other hunger-related hormones, such as fasting. The release of kisspeptin activates gonadotropin-releasing hormone, or GnRH, which, in turn, signals the pituitary gland to produce follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH does precisely what it sounds like—it stimulates the growth of follicles in the ovaries. LH tells the ovaries to release estrogen and progesterone and, during ovulation, an egg. Here’s the issue: Some studies, such as one study on fasting female rats (yes, rats, because of their similarity to humans anatomically, physiologically, and genetically), have found that kisspeptin and LH levels plummet. Low levels of these hormones throw the body out of whack and could seriously compromise fertility. But the limited research is less than conclusive. Other studies on women have shown little to no fluctuation in reproductive hormones. What to make of this?
Harnessing Hormones for Optimal Results
Listen to your body. Some women find they are more sensitive to the stress of fasting, especially in the week leading up to their period when estrogen levels decrease and increase their sensitivity to cortisol. If so, scale back on your fasting schedule that week. If you stop menstruating or feel like something is off, stop fasting and contact your health care provider.
On the flip side, many women thrive with intermittent fasting, which should be no surprise. The female body is designed to withstand more extended periods without food to protect a potential fetus. It can weather the storm better than the male body, providing incredible benefits.
On average, women have 6 to 11 percent more body fat than men, and they have a higher percentage of fat than men of the same weight, not only on their bodies but also within their muscles. More fat is a benefit. Stay with me. Women are designed to use fat as a primary energy source and are better at utilizing it. In a fasted state, women kick-start the fat-burning process sooner than men. Plus, the epinephrine released during a fast is more potent in women, burning more fat than the same amount of epinephrine in men. And during exercise, women use more fat for fuel while breaking down less protein.
| Fasting Myth | Fasting Fact |
|---|---|
| You’ll lose muscle. | You’ll preserve muscle and be able to build higher-quality muscle. |
| Your metabolism will slow. | Your metabolism will not slow as your body has plenty of fuel from fat to supply all of its needs. Your metabolism is more likely to slow on a steady calorie-restricting diet. |
| Women shouldn’t fast. | Women are uniquely designed to thrive with intermittent fasting. |
Although the essentials of intermittent fasting are the same for everyone, I recommend that women pay extra attention to their thyroid and estrogen because many experience thyroid-related symptoms, such as hypothyroidism (underactive thyroid), often caused by autoimmune disease. To be clear, intermittent fasting has not been shown to harm the thyroid gland or significantly change hormone levels. However, supporting the thyroid as much as possible makes sense because women are prone to thyroid-related issues. I offer ways to do so throughout the book.
Estrogen dominance, a hormone imbalance in which estrogen levels are high compared to progesterone, is also increasingly common among women of all ages. Estrogen affects much more than the menstrual cycle, including the brain, heart, and urinary tract, as well as bone, breast, and skin health. Keeping estrogen under control is critical for overall good health and to reap the maximum benefits from intermittent fasting.
How Long is Intermittent Fasting
There’s no “perfect” fasting length, only the length that works for you, your body, your lifestyle, and your goals. Intermittent fasting is like the Swiss Army knife of wellness practices. You can use it in various ways to attain various results and goals. When deciding how long to fast, consider the following:
Where you are on your intermittent fasting journey: New to fasting? Start with a twelve-hour fast two or three times a week and increase the window up one hour each time, every week, until you hit a length that makes you feel good, energized, and upbeat. The idea is for intermittent fasting to become a lifestyle, which means making it sustainable. There’s no point jumping into a twenty-hour fast before you’re ready and feeling so cruddy you never want to fast again. Go at your own pace.
Your goals: Fat loss? Longevity? More energy and focus? Research tells us that specific fasting lengths support certain benefits, making it easy to tailor the size to help your goal best.
Experimenting: Don’t hesitate to mix things up and evaluate how you feel after different fasting lengths or even with different fasting lengths each week or month. I’m a big fan of cycling through other fasting times. Just remember the goal: to feel unique, physically and mentally. Listen to your body. If you feel less than excellent, reduce the time and frequency of your fast until you get to a good place.
Individuality matters: Your unique body, eating habits, and health history are significant factors that affect when you will experience certain benefits from fasting. The longer it takes to utilize your glucose and glycogen stores, the longer it takes to reach fat-burning mode. You may see benefits at sixteen hours that your best friend gets at twenty hours. The following benchmarks are generalizations, meaning what happens in most cases. The recommendations in this book are geared toward getting you to the best possible results in the most efficient way.
Over time, frequent intermittent fasting results in less hunger. If you struggle with hunger as a significant barrier to losing weight, intermittent fasting helps you overcome that hurdle for good.
What is The Best intermittent Fasting Window To Lose Fat?
Twelve-Hour Fasting Window/Twelve-Hour Eating Window
A twelve-hour fast is an excellent place to start if you’re new to fasting or want to ease into it, testing the waters to see if it suits you. Benefits include:
Gut microbiome reset. An imbalanced and unhealthy gut microbiome overpopulated with “bad” bacteria is linked to digestive troubles, high blood sugar, and weight gain. A twelve-hour fast will help kill the harmful bacteria and help rebalance your gut microbiome.
Food awareness. Food awareness is a potent psychological effect of a twelve-hour fast that should not be undervalued but is often overlooked. So many of us don’t eat with intention. We eat based on emotion, impulse, and stress. A twelve-hour fast allows you to become more aware of when you eat and why you eat. Successfully doing a twelve-hour fast gives you the confidence and discipline boost to take on longer fasts when additional benefits kick in.
Sixteen-Hour Fasting Window/Eight-Hour Eating Window
This is one of the most common fasting schedules because it’s where the magic begins. After sixteen hours, AMPK has been activated, and your body has likely switched from burning glucose and glycogen for fuel to burning fat. You’re continuing to starve the harmful bacteria in your gut to reset your microbiome while also experiencing:
Insulin vacation. You’re giving your pancreas a break once you approach the sixteen-hour fasting mark. Overproduction of insulin can lead to insulin resistance when cells don’t respond well to insulin and lose their ability to use glucose.
Fat burning. As insulin levels dive, gluconeogenesis ramps up to convert glycerol from fat into glucose. To feed that gluconeogenesis fire, you’re burning more and more fat.
Improved memory, focus, and brain function. With the acceleration of gluconeogenesis comes increased ketone production and all its associated benefits.
Longevity. Autophagy, the body’s recycling process, clears out the parts of cells that are weak and damaged, leaving you with more potent cells.
Eighteen- to Twenty-Hour Fasting Window/Six- to Four-Hour Eating Window
Pushing a little past sixteen hours into the eighteen- to twenty-hour fasting window amplifies all the benefits of a sixteen-hour fast. The fat-burning fire lit at sixteen hours is still raging and blazing up even more of your fat stores. Ketone production increases, and the difference can be substantial—in some studies, ketone levels doubled from fifteen to twenty hours. Autophagy continues its cellular rejuvenation and anti-aging work.
Doing a twenty-hour fast brings more cellular rejuvenation and longevity benefits, especially by strengthening your cardiovascular system. Fasting for this length of time has been linked to an increase in vascular endothelial growth factor (VEGF), a signaling protein that promotes the growth of new blood vessels. Bonus: By increasing blood flow, VEGF also helps turn white adipose tissue, the fat you’re probably most familiar with—typically in your hips, stomach, and thighs—that stores extra energy into the mitochondria-rich fat-burning brown adipose tissue. One more example of how fat burning is amplified.
| White Fat | Brown Fat |
|---|---|
| Stores energy in large droplets throughout the body | Stores energy in many smaller droplets, primarily around the neck, shoulders, and spinal cord |
| Provides insulation | Packed with mitochondria to burn fat and calories and generate heat |
| Functions as an endocrine organ, releasing hormones responsible for regulating numerous functions throughout the body | Linked to weight loss and improved blood sugar and insulin levels |
| Too much leads to obesity and a higher risk of developing certain chronic conditions | Can be created from whit |
Find the Best Fasting Length for You
| If You Want To . . . | Fasting Length |
| Begin a fasting regimen | 12 hours |
| Increase your food awareness | 12 hours |
| Reset and rebalance your gut | 12+ hours |
| Boost brain function | 16+ hours |
| Burn fat | 16+ hours |
| Improve insulin sensitivity | 16+ hours |
| Promote longevity | 16+ hours |
| Optimize all the benefits of fasting | 18 to 20 hours |
Finding a fasting time frame that fits your lifestyle can be tricky. The good news is there’s a lot of flexibility here; ultimately, the choice is entirely yours. A few things to consider:
Your fasting window officially begins after the last bite of food enters your mouth. Avoid eating after the sun goes down. This prescription means no late dinner before the start of your fast or breaking your fast at 10 p.m. Why? The body runs optimally when it’s in sync with the circadian rhythm, the twenty-four-hour sleep-wake cycle regulated, in large part, by light and dark. Light triggers a hormonal cascade, signaling the body to wake up and be active, whereas darkness signals sleep and restorative mode. You might think that when you’re asleep, you’re storing fat, but the opposite is true: You’re more likely to burn fat at night because you’re not consuming food. The body can’t manufacture fat from thin air, after all. We need to give our body plenty of time in therapeutic mode, and that means when it’s time to sleep, we should not be eating.
One recent study found that women who consumed their last meal between 7 p.m. and 7:30 p.m. lost almost 5 pounds (2.25 kg) more than those who consumed their last meal between 10:30 p.m. and 11 p.m.. They had lower fasting glucose levels, better triglyceride levels, and other key biomarker improvements.
Living in sync with your circadian rhythm will positively affect your metabolism and energy levels, helping you achieve better results. This schedule goes for fasting and nonfasting days.
Preferred intermittent Fasting Schedule
To get the most benefit from fasting, you should work out toward the end of your fast. Regarding fasting schedules, play around with timing. Don’t be afraid to try a couple of schedules and mix them up throughout the week. It’s good to keep your body guessing. Some fasting schedules to consider include the following:
You are beginning your fast after dinner, at 7 p.m. Starting a fast after dinner is an excellent way to go. This means eating your last meal of the day, fasting through the night while you sleep, and then breaking the fast in the afternoon or evening the following day, depending on your fasting window. For example, a sixteen-hour fast with this schedule could mean beginning a fast at 7 p.m. and ending it at 11 a.m. the following day. This schedule has you skipping breakfast, which, for many people, is pretty simple. Of course, extending your fast extends the fasting window into more of your day. Beginning a twenty-hour fast at 7 p.m. means breaking it at 3 p.m. You get the idea.
Beginning your fast in the afternoon, at 4 p.m. Skipping dinner can be more challenging for some, but this timing is an excellent way to stay in alignment with your circadian rhythm and fit in a workout in the morning. Starting the fast at 4 p.m. means you’d break a sixteen-hour fast at 8 a.m.
Top Tactics in Intermittent Fasting
Skip Dinner: Participants in one study who fasted for eighteen hours with a six-hour eating window from 8 a.m. to 2 p.m. showed lower levels of the “hunger hormone” ghrelin, decreased appetite and daily hunger swings, increased fat burning, and improved metabolic flexibility (the body’s ability to switch between burning carbs and fats) compared to those who fasted for twelve hours with breakfast at 8 a.m. and dinner at eight p.m. Try eating earlier in the day and fasting in the afternoon and overnight.
HOW OFTEN TO FAST
I don’t recommend fasting every day. It’s called “intermittent” fasting because you are intended to fast at irregular intervals, not regularly, continuously, or steadily. The benefits of intermittent fasting come when it’s done sporadically, shocking your body to better adapt to fat burning.
You may lose weight fasting every day simply because you’re not taking in as many calories as you were before you started fasting, but eventually, you’ll hit a plateau. In a phenomenon known as adaptive thermogenesis, your body gets used to running on fewer calories. Then, it lowers your metabolism, requiring you to either eat less and less to lose weight or exercise more and more for the same result. Anyone who has tried to sustain weight loss by restricting calories knows it’s a dead end.
Calorie restriction is not the goal of intermittent fasting; flipping the body’s metabolic switch so the body becomes more efficient at burning glucose and fat for fuel is. Rather than fast every day, fast, bright, and strategic to maintain its effectiveness and achieve the maximum benefit. Here’s what I recommend:
- Beginners: Fast two or three times per week.
- Maximum: Fast three or four times per week.
That said, there is no hard and fast rule. Just as you’ll experiment to find the fasting length that works best for you, try a variety of fasting schedules to find what best suits you and monitor your results. Do you feel good? Are you seeing the results you want? Is your schedule sustainable? If you answered “no” to these questions, dial back your fasting schedule. Fasting too much will prevent you from reaping the maximum benefits.
LET’S BREAK IT DOWN
- Intermittent fasting is one of the most powerful ways to get in shape and enhance your body, mind, and life.
- The basics are simple: Don’t eat for a set period (the fasting window) and then consume all your daily calories during another set period (the eating window).
- When you eat, your body is in storage mode, banking excess macronutrients such as glycogen and body fat.
- When you fast, your body burns, breaking down stored glycogen and body fat for fuel.
- Listen to your body and don’t hesitate to try different fasting lengths and schedules until you find what works best for your lifestyle and that makes you feel physically and mentally energized.
- Keep the “intermittent” in “intermittent fasting”—don’t fast daily.
28-Day Diet Plan For Intermittent Fasting
Creating a 28-day diet plan for intermittent fasting requires careful consideration of your goals, dietary preferences, and lifestyle. Here’s a general outline for a 28-day intermittent fasting meal plan. Remember to consult with a healthcare professional or registered dietitian before starting any new diet plan, especially if you have underlying health conditions.
Note: This plan uses a 16/8 intermittent fasting method, where you fast for 16 hours and eat during an 8-hour window. Adjust the fasting and eating windows to suit your preferences and needs.
Week 1-2: Transition Phase
- Day 1-3: Focus on reducing your eating window gradually. Start with a 12-hour fasting window and a 12-hour eating window.
- Day 4-7: Extend your fasting window to 14 hours and eat during a 10-hour window. Eat balanced meals during your eating window.
Week 3-4: Establishing the Routine
- Day 8-14: Continue with a 14-hour fasting and 10-hour eating window. Begin incorporating healthier food choices.
- Day 15-21: Gradually increase your fasting window to 16 hours with an 8-hour eating window. Opt for nutrient-dense meals.
- Day 22-28: Maintain the 16/8 fasting and eating schedule. Focus on balanced, whole-food meals.
Sample Daily Meal Plan (16/8 Intermittent Fasting):
Please adapt portion sizes and specific food choices based on your dietary preferences and calorie needs.
Breakfast (During Eating Window):
- Scrambled eggs with spinach and tomatoes
- A serving of Greek yogurt with berries
- Herbal tea or black coffee (without sugar or cream)
Lunch (During Eating Window):
- Grilled chicken breast or tofu salad with mixed greens, cucumbers, and vinaigrette dressing
- Quinoa or brown rice
Snack (During Eating Window, if needed):
- A small handful of almonds or walnuts
- A piece of fruit (e.g., apple or pear)
Dinner (During Eating Window):
- Baked salmon with roasted broccoli and sweet potatoes
- A side salad with olive oil and vinegar dressing
Snack (Optional, During Eating Window):
- Greek yogurt with honey and a sprinkle of nuts
Hydration:
- Drink plenty of water throughout the day during fasting and eating windows.
- Herbal teas, black coffee (without additives), and plain sparkling water are also allowed during fasting.
Notes:
- Aim for a well-balanced diet with a variety of lean proteins, healthy fats, fruits, vegetables, and whole grains.
- Pay attention to portion sizes to avoid overeating during the eating window.
- Listen to your body and adjust the plan based on hunger cues and energy levels.
- Consult with a healthcare provider or dietitian if you have specific dietary restrictions or health concerns.
Remember that intermittent fasting may not suit everyone, so it’s essential to consult with a healthcare professional before starting any new eating regimen.
Why I Stopped intermittent Fasting?
There could be various reasons why someone might decide to stop intermittent fasting. Here are a few possible answers to why someone might stop intermittent fasting:
- Unsustainable Routine: Intermittent fasting can be challenging to maintain long-term. Some people find it hard to adhere to the strict eating windows and may feel it’s not a sustainable lifestyle for them.
- Health Concerns: Individuals with certain medical conditions or histories might be advised against intermittent fasting by their healthcare providers. For example, if someone experiences negative health effects or has a history of eating disorders, it’s crucial to prioritize their well-being over a fasting regimen.
- Weight Plateau: While intermittent fasting can be effective for weight loss initially, some people may hit a plateau where they stop seeing significant results. This frustration could lead them to try other approaches.
- Social or Lifestyle Factors: Intermittent fasting can sometimes interfere with social events, family meals, or personal preferences. If it causes discomfort in social situations or negatively impacts one’s quality of life, they may decide to discontinue it.
- Hormonal Imbalances: In some cases, particularly for women, intermittent fasting can disrupt hormonal balance and lead to irregular periods or other hormonal issues. This could prompt someone to reconsider their fasting routine.
- Increased Stress: Fasting can induce stress on the body, particularly during the adjustment phase. If the stress becomes chronic or overwhelming, it may outweigh the benefits of fasting.
- Dietary Restrictions: Some individuals might find it difficult to meet their nutritional needs or specific dietary goals within the limited eating windows of intermittent fasting.
- Personal Preferences: Ultimately, everyone’s body is different, and what works for one person may not work for another. Personal preferences and how one’s body responds to fasting play a significant role in deciding to stop.
It’s essential to note that intermittent fasting is not suitable for everyone, and individuals should always prioritize their health and well-being when considering any dietary or lifestyle changes. Consulting with a healthcare professional or registered dietitian can provide personalized guidance based on individual circumstances and goals.
