If You Want to Lose Weight With Intermittent Fasting, Here's a Must-Read Beginner's Guide

There are tons of reasons to try intermittent fasting (IF) such as disease prevention and improved digestion and reduced bloating, but weight loss is what draws most people to it. If you're new to the whole idea, this intermittent fasting guide will explain all the details.

Just note that intermittent fasting may not be right for everyone, especially those with a history of disordered eating. Registered dietitian Lisa Eberly Mastela, MPH, RD, told POPSUGAR that any form of IF should be done under the supervision of a registered dietitian.

If you're ready to dive in, here's what beginners need to know about how to use intermittent fasting to lose weight.

It's Not a Diet
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It's Not a Diet

Intermittent fasting isn't a diet; it's a pattern of eating that focuses on a period of time where you fast and a period of time where you eat. Whether you eat plant-based, low-carb, keto, gluten-free, or Paleo, anyone can do intermittent fasting with the diet they're already eating.

People find weight-loss success with IF because it's sustainable, and you never feel deprived because it doesn't require you to cut out food groups. It can also allow freedom from the strict calorie counting you may have tried in the past that made your diet feel too calculated and restrictive. You just want to be mindful not to eat 5,000 calories of pizza and candy during your feeding window and still expect to lose weight; you want to eat healthy, whole foods (more on that later) until you're satiated but not stuffed.

Another great thing about IF is that you can eat larger portions, which helps you feel more satisfied. IF is a lifestyle that you can use to both lose and maintain your weight, and from my personal experience, it feels effortless.

Get Checked by Your Doctor Before You Start
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Get Checked by Your Doctor Before You Start

Before beginning this new eating lifestyle, make an appointment with your doctor. Have your blood pressure and heart rate checked, as well as a panel of basic blood work. Talk with your practitioner about your plan, making sure he or she is on board with you doing it.

Aside from feeling good about knowing that you're healthy enough to start intermittent fasting, it'll be great to go back for a follow-up appointment and be able to compare your blood pressure, cholesterol, weight, and other numbers to see how much they've improved.

You may also want to make an appointment with a registered dietitian. You can discuss which IF method would be the best for your lifestyle. They can also help you formulate a daily eating plan that's balanced and offers your body what it needs for its health and fitness goals.

The Best Methods of IF For Beginners
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The Best Methods of IF For Beginners

There are so many different types of intermittent fasting, and these are the best methods for beginners:

  • 12:12: You eat for 12 hours of the day and fast for the other 12. For example, you'd eat from 7 a.m. until 7 p.m. every day. This is perfect for IF newbies as it's consistent every day, you can eat three regular-timed meals, and it can help those who tend to overindulge with bedtime snacks.
  • 14:10: You fast for 14 hours of the day and eat for the other 10. This could be a great next step after trying 12:12. An example would be that you eat from 10 a.m. until 8 p.m., perfect for those who don't like to eat breakfast right away.
  • 16:8 or Leangains: Probably the most popular form of IF, you eat for eight hours of the day and fast for 16. An example would be eating from noon until 8 p.m., basically just skipping breakfast. This is something you can do every day and still be able to enjoy dinner with the family or out with friends. If you're a morning eater, you can eat from 8 a.m. until 4 p.m. — you can make the eight-hour eating window work for you.
  • 5:2 or Fast Diet: Twice a week (nonconsecutive days) you restrict calories to around 500 calories a day (600 calories for men), and on the other five days, you eat as if you are not on a diet. On the fasting days, you can eat three small meals or two slightly larger meals (lunch and dinner).
  • Eat, Stop, Eat: Once or twice a week, you fast for 24 hours, but you never go a day without eating. Eat dinner Monday night, finishing by 6 p.m., fast all day Tuesday, then eat dinner at 6 p.m. on Tuesday night. Start with building your way up to fasting for 18 hours, then 19, then 20, etc., until you make it to 24. Do this once a week at first, then build your way up to two 24-hour fasts.
Here's How to Choose the Right Method
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Here's How to Choose the Right Method

Research all the methods and choose the one that best suits your lifestyle, taking into consideration your work schedule, your workout routine, your family life, and your goals. There is no one plan that's best or the most effective — it's whichever plan is best for you, one that you can easily maintain.

Many people begin with the 12:12 plan, then move to 14:10, then to 16:8. Some may prefer doing 5:2, because they only have to think about fasting twice a week, and longer fasts may be more effective for you. Try a method for a few weeks and see how you feel, then modify if you need to.

How to Begin
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How to Begin

After seeing your doctor and choosing the right plan for you, the very first thing you need to do is identify your "why," or your purpose. Keeping this in mind is what is going to inspire you to stick with intermittent fasting when moments get hard.

Your "why" could be that you want to lose weight so you can enjoy running around with your kids. Or maybe you want to prevent weight-related diseases like type 2 diabetes or heart problems. Or maybe your "why" is to feel more confident in your skin.

Even though you may be doing intermittent fasting for weight loss, your "why" may also be to get control over your food addiction or sugar cravings. Stephanie Ferrari, a registered dietitian with Fresh Communications, said intermittent fasting can help curb sugar cravings if you do it long enough. When you're eating less, you're bound to eat less sugar, and the less sugar you eat, the less you crave it.

Or your reason to do IF may be to cure digestive issues or constant bloating, since I found IF can help with both those issues. Although everyone's body is different, when I took a break from IF, my bloating issues came back.

Write down your purpose in a journal so you can refer back to it when you have thoughts of giving up. Once you know your "why," begin incorporating intermittent fasting slowly. Even if you're a jump-straight-in-the-pool kind of person, it's better to take a one-step-at-a-time approach. If you go from eating three meals and three snacks a day to eating only 500 calories a day (5:2 plan), you're more likely to have terrible side effects, including headaches, dizziness, and even nausea.

There's no rush! Take several weeks to ease into the plan you've chosen. If you're especially hungry on a certain day or not feeling well or expecting your period, listen to your body and eat if you need to.

When You're Not Fasting, Eat This
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When You're Not Fasting, Eat This

One of the amazing things about intermittent fasting is there are no restrictions on what you can eat during your eating window. You can eat whatever foods you like, including the ones you may have cut out when trying to lose weight in the past, like bread or wine. Since you're saving calories by fasting during certain times of the day, you can enjoy pizza or ice cream every once in a while and still lose fat — the 80/20 rule works great with intermittent fasting!

That being said, you'll have the best results if you focus on mostly healthy, whole foods. Ferrari told POPSUGAR that if you want to lose fat (especially belly fat), avoid refined carbs, sugar, and fast food, and load up on lean proteins, complex carbs, healthy fats, and fresh fruits and veggies. If you have medications or vitamins, take them during this time.

You can structure your meals and snacks however you like during your eating window. Just make sure you eat enough during your eating windows, meaning eating until satiation (but not overeating). This will help you feel more satisfied when you're fasting.

When You're Fasting, Here's What You Can Have
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When You're Fasting, Here's What You Can Have

This is easy to remember, since it's a short list.

  • Water of any kind, including sparkling and mineral, just avoid any that contain fruit juice or sweeteners, even stevia. Some experts say you can have a slice of lemon in your water or a splash of apple cider vinegar. If this is necessary for your compliance, go for it, but if not, drink it plain.
  • Black coffee is allowed, just avoid cream or sweeteners (both sugar and sugar-free sweeteners) — this includes Bulletproof Coffee.
  • Herbal tea.

Avoid BCAAs, smoothies, protein shakes, sports drinks, and bone broth. Fasting expert Jason Fung, MD, a nephrologist (kidney specialist) and author of The Complete Guide to Fasting, told POPSUGAR that even chewing gum can "produce an insulin response." The point here is that if you take in calories, then you're not technically fasting.

These Are the Common Side Effects You'll Experience
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These Are the Common Side Effects You'll Experience

In the first couple weeks of intermittent fasting, you may experience these not-so-fun side effects:

  • Headaches
  • Fatigue and low energy
  • Inability to concentrate
  • Irritability (feeling hangry)
  • Feeling cold
  • Nausea
  • Insomnia
  • Hunger

Fasting will be challenging for the first four to seven days because of these annoying and uncomfortable side effects, and maybe even for longer, but Dr. Fung told POPSUGAR that your body quickly adjusts.

After the first week or two, your mind will feel clear, you'll likely have more energy and improved sleep and digestion, you'll actually feel less hungry, and you'll look leaner. So hang in there! If you're still feeling these symptoms after a few weeks, talk to your doctor.

If at any point these symptoms feel debilitating (i.e. if you feel like you're going to pass out or are so hungry you can't concentrate at work), try adjusting to another IF method, such as a shorter fasting window. Otherwise, IF may not be for you — and that's OK! Every body is different.

Here's How to Deal With Side Effects
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Here's How to Deal With Side Effects

To prevent these side effects, drink plenty of water. Pound a big glass right when you wake up, and drink throughout your fast.

Caffeine can also help, so sip on black coffee or green tea. If you're fasting for longer periods of time, putting a little pink Himalayan sea salt in your water can prevent feeling foggy-headed. Going for a walk or light stretching can also make you feel better.

Here's How to Safely Deal With Hunger
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Here's How to Safely Deal With Hunger

A little grumbly tummy and light hunger is totally normal, but just know that it comes in waves, meaning it'll soon pass, and it never really gets more intense. Listen to your body, though! If insatiable hunger persists or you feel terribly ill, nauseated, or like you're going to pass out, shorten your fasting time and eat. You can try fasting again tomorrow.

Once your body gets used to this new eating schedule, you won't feel hungry anymore, but in the meantime, here's how to deal with hunger:

  • Keep in mind the reason you are fasting: If you summon that big reason when hunger pangs strike, you can just embrace them — a positive attitude goes a long way.
  • Drink tons of water! Staying hydrated will help prevent hunger as well as the headaches dehydration can cause. When you're hungry, pound 12 ounces of water; it helps fill you up.
  • Caffeine is another faster's friend: Go for black coffee or green tea. Herbal tea and sparkling water are other zero-calorie drinks that can help curb hunger. Just stay away from the zero-calorie sodas and other beverages made with artificial sweeteners.
  • Keep busy: Focus on work, take a walk, do a hobby, write in your journal, spend time with friends, clean the house . . . doing anything that occupies your brain away from food is a plus!
  • Stay away from food: When you first start fasting, the temptation to eat is huge. Don't make it harder by grocery shopping, walking past your favorite bakery, fasting during your friend's birthday dinner, or preparing food for other people. When you're starting out, go with this motto: "If I don't see it, I can't eat it."

Note that having your period, feeling super stressed, not getting enough sleep, eating tons of refined carbs during your eating window, and intense exercise can increase hunger. Don't ignore it if that means you can't function normally.

You Want to Avoid These Mistakes, Which Can Lead to Weight Gain
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You Want to Avoid These Mistakes, Which Can Lead to Weight Gain

In the first few weeks and months of your IF journey, here are some mistakes to avoid:

  • Choosing the wrong plan: Be realistic about what plan will work with your lifestyle, personality, and body. 5:2 may sound good on paper because fasting longer each day can help you lose weight faster compared to a plan like 16:8, but if you have a stressful job where you work long hours, this will be hard to maintain.
  • Doing too much, too soon: Maybe you want to work up to 16:8, but you'll find the most success sticking with IF if you start off with 12:12 to allow your body time to adjust.
  • Giving up too soon: Intermittent fasting takes a certain amount of discipline and a period of time where you may not feel good or see results. Unless you're experiencing unbearable issues where intermittent fasting is affecting your ability to sleep or do your normal day-to-day tasks, or you find that it doesn't work with your lifestyle, then stick with it for at least a month before throwing in the towel.
  • Eating too much during your eating window: Don't make up for lost time by eating way more than you would if you weren't fasting. Intermittent fasting doesn't give you a green light to overeat, because you will gain weight.
  • Eating too little: If you don't eat enough, you'll feel especially hungry the next day, which can cause you to overeat. Make sure to never dip below 1,200 calories (unless you're doing 5:2), especially if you're working out. For reference, the USDA dietary guidelines recommend adult women consume 1,600 to 2,400 calories a day, but that number will vary based on your age, height, weight, and activity level. Eating too little will not only slow down your metabolism, but it will also make you so ravenous that you won't be able to fast, or you'll overeat when you do eat.
  • Eating the wrong foods: Skip the fast food and refined carbs and get your fill of protein, healthy fats, fiber, and complex carbs. This will satiate you longer, continue to help you build muscle, maintain a healthy brain, and just make you feel more energetic and happier overall.
What You Need to Know About Exercise
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What You Need to Know About Exercise

If exercising regularly is already part of your life, when you first start intermittent fasting, you may need to modify your workout routinehunger from intense workouts will make it much harder to stick to your plan.

If you're used to hitting the gym in the morning, fasted workouts might "feel hard at first," Precision Nutrition coach and fitness trainer Austin Lopez, CSCS, told POPSUGAR. This is especially true if you usually eat before a workout and if your workouts are vigorous, "but your body gets used to it," he said, and soon you may even prefer it.

On the other hand, working out while fasted might make you feel super tired and unable to go as intense as you want, warned Kellilyn Fierras, MS, a registered dietitian, NASM-certified personal trainer, and instructor at EverybodyFights in Boston. If that's the case, listen to your body, and shift your workouts to a time during your eating window instead.

Or you might find exercise is too difficult to do at all when you first start intermittent fasting. So focus on getting your IF schedule established, which might mean putting your workouts on hold, doing easier forms of exercise, or changing the times you work out to suit your IF schedule. Gradually work up to your regular workout routine; this shouldn't take more than a few weeks.

How to Track Your Progress
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How to Track Your Progress

One way to know you're losing weight is if you weigh yourself throughout your IF journey. Maybe weighing yourself every day will help you stay accountable, or you may prefer weighing yourself a couple times a week or once a week. Your weight can fluctuate from day to day, so as long as your weight is trending down, you can stick with your plan.

Be aware that working out can cause muscle gain, which will actually show numbers increasing on the scale, so also be sure to take measurements and progress pics. The numbers won't mean a thing if your before-and-after photos prove IF is working.

Since weight loss isn't the only benefit of IF, also take note of how you feel. Do you have more energy, a clearer mind, and better digestion and are you sleeping better? Do you feel more in control of your eating habits and your cravings? Do you have a lightness about you because you finally feel free from restrictive diets? Do you feel happier? Write all this down in a journal so you can look back and determine if intermittent fasting is working for you.