How to Do Intermittent Fasting: Diet Guide
This guide is for general information purposes only. We are providing what we hope will be a helpful resource, not a guaranty of success. We are not providing medical advice. Please consult with a doctor if you need such advice.
How to Do Intermittent Fasting: Diet Guide
Intermittent fasting is the latest diet craze, but is it for you? No matter what your reason for trying this dieting method — weight loss, improving health or simplifying your lifestyle — it can have powerful effects on your body and brain. Even if abstaining from eating for extended periods of time sounds crazy to you, give it a chance! Read on and learn about all the benefits of skipping a meal now and then.
What is Intermittent Fasting?
Humans have been fasting for thousands of years, sometimes by choice, for religious reasons or because there simply wasn’t food available. Human bodies are built to withstand periods of hunger, so it’s not unnatural to skip a meal here and there.
Intermittent fasting is an eating pattern that cycles between periods of fasting and eating. Eating this way has been shown to result in multiple health benefits including
- Vastly increasing the levels of human growth hormone (HGH), which causes fat loss and muscle gain, helps you recover from injury and disease, boosts metabolism and improves strength and exercise performance
- Extending lifespan and slowing brain aging
- Improving insulin sensitivity and lowering the amount of insulin in the blood, which makes stored body fat more accessible
- Initiating cell repair, which removes toxic proteins that can cause neurodegenerative diseases like Alzheimer’s, provides energy and regenerates healthy cells and tissues. It may also have a role in preventing cancer.
- Changing the expression of genes related to longevity and resistance to disease in a positive way
- Reducing body fat
In short, there aren’t any specific dieting rules other than deciding when to eat and when not to eat. However, when you eat, it is best to eat primarily healthy, nutritious food. These include lean proteins (skinless poultry, fish, legumes, tofu), whole grains, healthy fats and plenty of vegetables and fruits. To make it easier to choose foods, many nutritionists recommend combining intermittent fasting with the Mediterranean diet.
Intermittent Fasting Methods
So, how do you start reaping the benefits of this diet? There are a few methods of fasting that you can try, but the four most popular methods will be discussed here.
16/8 Method (Leangains)
Under the 16/8 method, you restrict your daily “eating window” to 8-10 hours. You can eat two to three meals within that time. A typical eating window schedule ranges from noon to 8 p.m. and skip breakfast in the morning. During a fast, you can drink water, coffee and other non-caloric beverages to reduce hunger levels. As the name suggests, you’ll be fasting for 16 hours, but if you’re sleeping eight hours each night, you’ll only be awake and fasting for about eight hours during the day.
The 5:2 diet involves eating only one small meal twice a week. On fast days, you mostly stop eating from dinnertime the previous day, eating only one 500-600 calorie meal during the day. You resume eating at breakfast the following day. Like the 16/8 fast, non-caloric beverages are allowed during your fast day. On an “eat day” you can eat a full slate of healthy meals. It’s important that you don’t fast for more than one day in a row so your body can get its proper nutrients on eat days. This method is a bit more difficult than the 16/8 method, but some practitioners can fast for as many as three days a week, a.k.a. alternate day fasting.
Eat Stop Eat
This method involves a complete 24-hour fast once or twice a week. During the fast day, you would consume only water and other zero calorie beverages. If you are doing this for weight loss, when you resume eating, you should eat a normal amount of food, like you would if you were not doing any fasting. Otherwise, there is a risk that you will binge and then not lose any weight.
With this method, you will eat just small amounts of clear broth, dairy, hard-boiled eggs, raw fruits and vegetables during the day and then eat one large meal during a four-hour window at night. At that meal, you would eat food like that on the paleo diet: whole, unprocessed proteins and produce.
According to Johns Hopkins Medicine, fasting times longer than 24 hours are not necessarily better for you and may be dangerous. In addition, longer fasts may trigger the body to go into starvation mode in which it holds onto fat and breaks down muscle for energy.
Are you curious about trying any of these methods? Explore some of the benefits of fasting below and see if you walk away convinced and motivated to start.
Does Intermittent Fasting Help You Lose Weight?
When we eat, our main energy sources are glucose and fatty acids. Glucose (sugar) is used for energy after we eat and any excess glucose is stored as fat. When we fast, the body breaks down the fat for energy because there is no glucose available in the blood. The liver converts fatty acids into ketones, which provide a high energy level for tissues, especially the brain. According to a review published in the Annual Review of Nutrition in October 2021, intermittent fasting results in about the same amount of weight loss as a diet that cuts caloric intake by 500 calories a day.
Weight loss was mild to moderate (a loss 1-8% of baseline weight). In addition to decreasing blood pressure, insulin resistance and oxidative stress, intermittent fasting helped participants by regulating appetite and causing favorable changes in the diversity of the gut microbiome. In a review of 40 studies published by the Harvard School of Public Health, the typical weight loss from intermittent fasting was 7-11 pounds over ten weeks.
Pros of Intermittent Fasting
As mentioned earlier, there are numerous health benefits to fasting. If beginning a fast sounds unpleasant, you may reconsider when you hear some of the reasons in favor of skipping lunch.
- Easy to start. There are no cookbooks, guides, measurements or any other precursors to start this diet. It’s as simple as refraining from eating.
- Add-ons. This eating plan works well with pretty much any other diet you’ve been meaning to try. Your best bet is a balanced diet with plenty of fruits and veggies.
- Multiple health benefits. Some studies suggest that fasting every other day showed many positive effects, such as stress resistance and increased insulin sensitivity.
- Reduces cholesterol. A study showed that intermittent fasting done on the Muslim holiday of Ramadan reduced total cholesterol, LDL (bad cholesterol) and triglycerides and increased HDL (good cholesterol) in participants.
- Promotes longevity. Intermittent fasting reduces morbidity and increases life span.
- Improves brain health and cognition. In a clinical trial, older adults improved verbal memory after intermittent fasting, while another study showed that it also improved executive function (decision making) and overall thinking.
- No category of macronutrients are restricted. Unlike low-carb, keto, vegan or paleo diets, no major macronutrient (protein, carbohydrates, fat) is eliminated, so it is easy to get all the nutrients your body needs.
- Resting your digestive system. Taking a break from eating frees up 65 percent of your body’s energy consumption to do other things, like concentrate better. Although you may feel some sluggishness on your first few fast days, this tends to pass in time.
- Weight loss. It’s a simple, well-known fact that eating less leads to weight loss. Fasting creates a caloric deficit that can lead to real results on the scale. As long as binge eating doesn’t occur on eat days, fasting can help those seeking to shed a few pounds.
- Quick and beneficial changes. A study looked at how a diet similar to fasting affected a number of health markers. After just three months, the participants lost 5.7 pounds on average, had lower levels of insulin, lower markers of inflammation, lower Body Mass Index (BMI), less trunk fat, smaller waist circumference, lower blood pressure and less cholesterol.
- Reducing risk factors for disease. A study in the journal Cell Metabolism showed intermittent fasting may decrease risk factors for diabetes, cardiovascular disease and cancer.
- Community. There are several online communities on Facebook and elsewhere that help promote intermittent fasting and can guide you on your journey.
Cons of Intermittent Fasting
There’s no way around it: starting regular fasting is hard. It’s not for everyone either, especially if you have certain health conditions or predispositions. Explore some of the reasons why fasting may not be the best choice.
- Difficult hunger pangs. Depending on your body and needs, it may be more difficult to get past the initial hurdle of hunger and make this into a consistent habit.
- Not recommended for pregnant or nursing women. Women who are pregnant or nursing should not attempt to fast, as their bodies are under increased caloric and physical demands.
- Not great for the sick. As with any change in diet, you should consult your doctor to see if fasting is right for you. Fasting can interfere with various medical conditions, such as diabetes and kidney and liver diseases as well as medications. If you have diabetes and want to try intermittent fasting, do it only under a doctor’s supervision since in some people, it can worsen insulin sensitivity.
- May contribute to disordered eating. Fasting is not recommended for those with a history of eating disorders.
- Risk of overdoing it. Extended fasting can lead to dangerous complications and health problems.
- May reduce physical activity. When you are fasting, the last thing you want to do is exercise, so your overall activity level may decline.
- Temptation to overeat on eat days. It is natural to want to reward yourself for doing something difficult like fasting, so you may be tempted to overeat or eat high calorie foods on eat days.
- Weight loss results similar to other calorie-cutting plans. A study found that of 100 overweight people assigned to one of three eating plans, those assigned a calorie-cutting diet and those who fasted fared about the same when it came to weight loss.
- High dropout rate. The same study found that 38 percent of those assigned to the fasting regimen gave up on the diet. However, this is less than the dropout rate for many other diets. Generally speaking, the dropout rate for all diets is 54%.
How to Do Intermittent Fasting
While getting started on a fasting diet is simple enough, it definitely isn’t easy. You may feel hungry and get irritable in the beginning, but usually after two to four weeks, your body will acclimate and you will feel better. The good news is that once you get through this adjustment period, you are likely to stick with the program.
Begin by setting a small goal of fasting through one meal, like breakfast. The 16/8 method might be better for those just starting out. If you prefer fasting on the 5:2 method, start by fasting through breakfast and lunch one day, then slowly moving on to fasting through dinner. Make sure to go at your own pace and no faster than that. Listen to your body!
If all of that seems too difficult, give a liquid, fruit or mono fast a try. By fasting on smoothies or small bowls of rice, you’ll get many of the benefits of fasting without having to fully commit. You may also want to change up your diet before undertaking fasting — transitioning from light, plant-based meals to fasting is much easier than if you’re eating carb-heavy meals.
When you do eat, make sure to include lean protein sources such as chicken breast, plain Greek yogurt, beans, lentils and other legumes, fish and shellfish, tofu and tempeh. You should also eat foods with plenty of fiber such as fruits, vegetables and whole grains. These two macronutrients will help you feel full so that you are not as hungry when you are in the fasting period.
How to Stay Motivated
Fasting takes a bit of extra effort and entails some discomfort, especially at first. How do you stay motivated when you’re feeling those hunger pangs? It may be good to find a fasting buddy or an online community so you can talk about your struggles. You may also want to write down your motivations for fasting and read them aloud once each day. Taking photos of your changing body may also keep you determined. An app like My Fitness Pal keeps track of your weight, caloric intake, progress photos and more. But also remember that in addition to weight loss, intermittent fasting is improving your overall health and resistance to chronic diseases like heart disease, type 2 diabetes, Alzheimer’s disease and cancer.
Set short-term goals and take it easy if you make a mistake. Your health won’t be built in a day. It’s the result of a collection of small choices you make over a period of time.
Preparing for Fasting
There’s not much prep work in a fasting diet, but you want to make sure to talk to your doctor before starting any fasting regimens. Also, remember to eat a whole day’s worth of meals before you set out on any fast. It’s easier and healthier to fast when you’ve gotten all your nutrients the day before. Focus on eating veggies and protein to stay feeling full for longer.
Have a water bottle handy, since it is important to stay hydrated while you are fasting. Drinking plenty of water will also make you feel more full. When you are tired of water, you can substitute other zero-calorie beverages such as herbal tea or black coffee.
If you want to be extra prepared before fasting, alter your diet one to two weeks before starting your new regimen. Reduce your intake of refined sugars and processed foods, and switch to a healthy diet full of fresh foods. You may also want to reduce your caloric intake and get some moderate amounts of exercise.
Here are some ways to make fasting easier.
- Stay hydrated. Keep plenty of calorie-free drinks available, especially water.
- Distract yourself. So that you stop obsessing over the breakfast you didn’t eat, plan activities for that time period like doing a hobby, reading, organizing or watching a movie.
- Take it easy. If you are doing the 5:2 fast or the Eat Stop Eat method, rest and relax on fast days and avoid doing anything strenuous. Gentle exercise like yoga or tai chi is fine and may be beneficial.
- Make it count. When you can eat, choose foods that are nutrient-dense with plenty of lean protein, fiber and healthy fats (like in salmon, avocados and olive oil). This is especially true when eating small amounts during the fasting period of the Warrior diet.
- Choose high volume food. Foods with a large physical volume like fresh fruits and vegetables and popcorn will fill you up without overloading you with calories.
- Pump up the flavor. When you eat flavorful foods, you may feel less hungry. Seasonings to use include spices, garlic, herbs and vinegar.
- Mix it up. Eat a variety of nutrient-dense foods during your eating period so you can ensure that you are meeting all of your nutritional requirements. It will also keep your blood sugar levels steady and contribute to weight loss and overall health.
A Day in the Life of Intermittent Fasting
While you can practice any kind of diet while practicing intermittent fasting, let’s focus on healthy, protein-rich and plant-based meals for breaking your fast. Here’s what a regular day on a 16/8 fast method looks like.
Breakfast: Skip this meal and don’t eat anything until lunchtime. You can have non-caloric drinks like coffee (and if you really need it, a non-caloric sweetener like Splenda).
Lunch: Creamy avocado and white bean wraps
- 2 tablespoons apple cider vinegar
- 1 tablespoon canola oil
- 2 teaspoons finely chopped, canned chipotle chile in adobo sauce
- ¼ teaspoon salt
- 2 cups shredded red cabbage
- 1 medium shredded carrot
- ¼ cup chopped, fresh cilantro
- A 15-ounce can of rinsed white beans
- 1 ripe avocado
- ½ cup shredded sharp cheddar cheese
- 2 tablespoons minced red onion
- 8- to 10-inch whole-wheat wraps or tortillas (4)
- Whisk the vinegar, oil, chipotle chile and salt in a medium bowl. Add cabbage, carrot and cilantro. Toss it together to combine.
- Mash the beans and avocado in another medium bowl with a potato masher or fork. Stir in the cheese and onion.
- Assemble the wraps by spreading about ½ cup of the bean-avocado mixture onto a wrap (or tortilla) and top it with about ⅔ cup of the cabbage-carrot slaw. Roll up. Repeat with remaining ingredients. Cut the wraps in half to serve, if desired.
Dinner: Roast chicken and sweet potatoes
- 2 tablespoons whole-grain or Dijon mustard
- 2 tablespoons chopped, fresh thyme or 2 teaspoons dried
- 2 tablespoons extra virgin olive oil, divided
- ½ teaspoon salt, divided
- ½ teaspoon freshly ground pepper, divided
- 1½ to 2 pounds of bone-in chicken thighs, skin removed
- 2 medium sweet potatoes, peeled and cut into one-inch pieces
- 1 large red onion, cut into one-inch wedges
- Position the rack in the lower third of the oven and preheat to 450 degrees Fahrenheit. Place a large-rimmed baking sheet in the oven to preheat.
- Combine mustard, thyme, one tablespoon of oil and ¼ teaspoon each of salt and pepper in a small bowl. Spread the mixture evenly on the chicken.
- Toss the sweet potatoes and onion in a bowl with the remaining one tablespoon of oil and ¼ teaspoon each of salt and pepper. Carefully remove the baking sheet from the oven and spread the vegetables on it. Place the chicken on top of the vegetables.
- Return the pan to the oven and roast, stirring the vegetables once halfway through, until the vegetables are tender and beginning to brown. Insert an instant-read thermometer into a chicken thigh and make sure it registers 165 degrees Fahrenheit. This should take 30 to 35 minutes.
Snack Suggestions: Hard-boiled eggs, cucumber sushi, avocado hummus, bell pepper oven fries, cool ranch crisps, apple chips, trail mix bites, froyo fruit bites, melon prosciutto skewers or pickle rollups.
Drink Suggestions: Water, coffee, tea, La Croix, red wine, fruit and veggie smoothies and anything without added sugars or too many calories.