Intermittent Fasting for the Vegan Athlete: Is It Right for You?

By: Pamela Fergusson, RD, PhD

Intermittent fasting is all the rage—but is right for you?

Fasting has long been a common practice in many cultures, used to promote mental health and longevity. More recently, it’s gained popularity as a weight loss tool. (And it happens to be one of our favorite weight loss approaches, right up there with minimizing calorie density.)

But significantly restricting your calories for a long period of time can be dangerous. Not to mention incredibly difficult, scary, and simply not fun.

That’s where intermittent fasting comes in. Intermittent fasting refers to dietary patterns that cycle between fasting and and non-fasting, to help you experience the health benefits of fasting without many of the downsides.

And studies have shown that it can help you lose weight, boost your metabolism, reduce the risk of certain diseases, and even improve your mood.

The best part? Intermittent fasting is completely natural.

According to a 2014 article in the journal Cell Metabolism authored in part by Valter Longo, the director of University of Southern California’s Longevity Institute, intermittent fasting may act as a low-grade stress, which triggers the body’s cellular defense mechanisms, repairing damage and fighting disease.

It’s a tool that helps to trigger our bodies’ own natural healing processes. And speaking as someone who has practiced it for over five years, I can tell you that it works.

 What is Intermittent Fasting?

Before we go any further, it’s important to explain what intermittent fasting actually looks like. It’s confusing, in part, because when people refer to intermittent fasting, they could be talking about several different approaches:

1. The 16:8 method where you eat within an eight-hour period each day and fast for the remaining 16 hours. When you’re fasting you can’t take in any calories, but you can consume non-caloric beverages, including coffee, herbal tea, water, and sparkling water.
2. The 5:2 method where you eat normally for five days of the week, and restrict your calories to 500 (women) or 600 (men) the other two days.
3. The eat-stop-eat method where you do one or two 24-hour fasts each week; for example, not eating after lunch until lunch the next day.
4. The alternate-day fasting method which involves eating normally one day, and then eating very low-calorie (500 calories) the following day.

As you can see, none of these calls for more than two days of complete fasting per week, and most allow for calories every single day.

In my opinion, as long as you stick to one of these four options, there’s no wrong way to approach intermittent fasting. Which option you choose has more to do with your preferences and needs, but I’ll get to that in a few minutes.

Intermittent Fasting on a Whole Food Plant-Based Diet

If I were to poll ten vegans about the ideal diet, I’m willing to bet at least nine of them would say “whole foods plant-based.” In our circle, the whole food plant-based diet (WFPB) is what most of us strive for.

It’s the top dog. The (vegan) crème de la crème.

But for some of even the strictest WFPB followers, it may not be enough. They may still struggle to find their ideal weight, or want to take their diet one step further.

I’ve had many people come to me in my practice and say that they feel they must be doing the WFPB diet wrong. That despite following it (and feeling great), they can’t seem to lose the extra weight. That’s relatable, because that has also been my own experience.

Even though I eat a WFPB diet—with the rare vegan treat, of course—and I am very active, I still have to rely on intermittent fasting to prevent weight gain.

But how do they work together?

As a vegan Registered Dietitian, I’ve see many people in my practice get the benefits of a WFPB diet combined with intermittent fasting. In fact, combining WFPB and IF is a highly anti-inflammatory way to eat, and may reduce your risk of disease even more than either approach can on its own.

5 Great Reasons to Consider Intermittent Fasting

Now that we know what it intermittent fasting is, and that it can work together with a whole foods plant-based diet, let’s talk about the why. That is, why intermittent fasting may be right for you.

Here’s what we know:

1. It’s simple. There are no extra supplements to take, and your meal prep and planning will be simplified because you’ll eat less often. As a result, it will likely reduce your food costs too.

2. It is effective. Intermittent fasting can be just as effective (if not more effective) as calorie restriction in promoting weight loss.

On top of that, studies have shown that intermittent fasting may:

3. Improve your mood and your focus. I know some of us get hangry when we don’t eat, but, with a little practice, fasting can actually improve your mood and focus. In fact, intermittent fasting may be successful in helping to treat depression.

4. Help you lose fat while preserving muscle mass. Unfortunately, when we lose weight, we don’t just lose fat, we lose muscle too. But intermittent fasting is more effective than calorie restriction at preserving muscle mass during weight loss.

5. Reduce your risk of disease, and possibly help you live longer too. Calorie restriction is one of the few things that has been proven to extend lifespan. Interesting … but are you now just going to be hungry and miserable for a longer period of time? intermittent fasting helps to alleviate that concern.

Some researchers argue that you can get may of the same benefits through periodic restriction, like intermittent fasting. It may also improve insulin sensitivity, reduce inflammation, and reduce risk of diabetes, cancer and heart disease.

Weight Loss Results: What to Expect

Weight loss with intermittent fasting is similar to the results with calorie restriction. If you are consistent, you can expect to see a loss of 1 to 2 lbs per week.

For some people, intermittent fasting may appear to work much better than calorie restriction or other similar methods, however this is likely to be because you’re able to be more consistent with it. I hate to break it to you, but if you’re not consistent, just like with any other diet, it won’t work.

Think of intermittent fasting as a lifestyle change, not something you will just do for a few weeks to get to race weight or to fit into a bridesmaid’s dress. It’s something you can do for life—just like going plant-based or picking up running.

When you reach your “happy weight” you can maintain it by fasting less often, or in a less restrictive window. This is what I do, and I love the results.

Who Should Try Intermittent Fasting

I believe that most people can benefit from some form of intermittent fasting, and that some people seem to really thrive with it.

If you’re an “all or nothing” person who finds moderation challenging (just how many vegan brownies is a once-in-a-while treat?!) then intermittent fasting may be perfect for you. That is one of the many reasons I myself love it.

It just makes eating and meal planning and snacking simpler. You’ll need to organize and prepare fewer snacks and meals and that reduces decisions and time spent in the kitchen.

And who knows, you might just save some cash too.

But Proceed with Caution—It’s Not for Everyone

Have I sold you on intermittent fasting yet? Before you dive in, let’s make sure it’s a good fit.

Fasting is not for everyone. It’s not a good strategy for if you are diabetic and take insulin, or if you are pregnant or breastfeeding. People who have a history of an eating disorder should be cautious with fasting because it might be a trigger for them.

Or, if you’re just the type of person who gets really hangry when you don’t eat (yeah, you know who you are), you probably shouldn’t practice intermittent fasting. If not for yourself, then for the sake of everyone who has to live or work with you.

Finally, some people just don’t like fasting, even after getting used to it. And if that’s you, that’s okay. Good for you for giving it a try.

How to Get Started with Intermittent Fasting

When I first tell most people about intermittent fasting, their eyes glaze over thinking about all the rules and complications. But it’s a lot simpler than it looks, as long as you’re smart about your approach to getting started.

1. Make a plan: For fasting to work it will require structure and rules, because as you can guess, there are times when it’s going to be hard.

But there are a number of ways to set those boundaries. When trying to select which protocol will work for you, follow your instincts. People usually have a sense of what might fit well into their lifestyle, and for some, trying to eat only 500 calories in a day seems too restrictive and they would rather try eating within an eight-hour window using the 16:8 method.

It’s less about which is best, and more about which is sustainable.

2. Ease into it: Going all-in on day one could result in no day two. Ease into it.

For example, It‘s fine to start with a twelve hour feeding window (say 7am to 7pm) and then move to a ten hour window before ultimately dropping to that eight hour window when you’re getting in that day’s calories. If you start with eight hours right off the bat, chances are it will be too hard to sustain.

3. Set a target: Like with any health and lifestyle improvement, intermittent fasting takes some time to have an effect. It is important to give a good try before deciding if it works for you. Set a target of trying it for 30 days.

Although fasting can be difficult at first, many people actually report that it gets easier with time. And after your target date, if it is not working out, don’t feel you need to give up on fasting entirely. You can always experiment with a different fasting protocol.

4. Plan to succeed: Meal planning while fasting? I know, I know …

But I still recommend it. We often make healthier choices when we plan in advance and have all the ingredients we need on hand; even better if we do some of the prep in advance. This is particularly important when you are fasting, because once your feeding window opens you’ll likely be hungry and want to eat whatever is fastest.

Instead, you should be focusing on healthy, fiber-rich meals that will sustain you when you are fasting.

My Top 3 Tips for Success

1. Don’t be afraid of a little hunger. Hunger tends to come in waves, and even if you are feeling very hungry now, you might not in 30 minutes if you can keep busy and take your mind off of food.

Many of us have become accustomed to continual snacking, and that is a habit that we need to break if we are to become successful at intermittent fasting. We can use our energy stores to support our activities when we are not fueling, and that will help us burn fat.

Of course if you are feeling lightheaded or can’t concentrate, it’s time to break your fast.

2. Stay hydrated. You will find fasting much easier if you drink lots of water or herbal tea. People often mistake the feeling of thirst for hunger, and drinking will keep your hands busy and help you feel fuller.

3. Once you know the rules, you can break ‘em … a little. One of the great things about intermittent fasting is its flexibility. If you are following 16:8 and your usual eating window is between 11:00 am to 7:00 pm, and you know you are going to a party in the evening and you would like eat and drink at that party, then you can adjust your window to later in the day: say 2pm to 10pm.

You could also try for a less restrictive window that day, like an eating window of 10 or even 12 hours. Finally, you could just take a day off from fasting. If you were faced with the same situation and you follow the 5:2 pattern, just move your fasting days around so they don’t fall on the day of the party.

Training while Intermittent Fasting:

Okay, now to the question I’m sure all No Meat Athletes have in the back of their mind: How will this affect your training?

Intermittent fasting can be successfully combined with running, swimming, walking, zumba, martial arts, Crossfit, and just about any fitness activity.

At a recent Academy Workshop on intermittent fasting I hosted with Doug, we discussed this topic. You can watch that clip here:

(Want to watch the entire Workshop? Register for free here.)

We have enough glucose stored in our liver to support moderate intensity activity for 90 minutes or so, and 30-60 minutes for high intensity. You can do these workouts without fueling.

Keep in mind, however, that not fueling may impact your performance. If you find that’s the case, try doing your workout during your eating window or on non-fasting days. You may also decide that for the moment weight loss is more important to you than gains in performance. For most people the difference in performance with or without fueling on shorter efforts is marginal. Give it a try before deciding that you need your pre, during, and post workout snacks.

The one possible exception to this is long efforts.

If you are a marathon or ultramarathon runner or a distance cyclist, and your workouts last several hours, you will almost certainly need to fuel during those workouts. In that case, try to workout during your eating window, or don’t fast on the days when you do your long run. If that seems impossible to coordinate, then maybe intermittent fasting is not for you. You can perhaps try it at a later time, when your race goals and workout plan has changed.

Intermittent Fasting FAQ

What can I drink during Intermittent Fasting?

Hydration is very important during fasting. Drinking plenty of water can help stave off hunger pains, especially when you’re first adjusting to this new way of eating. It is perfectly fine to drink any liquid that has 0 calories. This can include coffee (black, or a very small amount of plant-based milk), tea, sparkling water, and even some sports drinks (so long as they are 0 calorie).

Can I take supplements during IF?

Supplements are an important part of any diet, and it’s certainly safe to take them during fasting. Since some supplements can cause discomfort on an empty stomach, you should be sure you schedule your eating window and supplement-taking schedule accordingly, so you don’t take your supplements on an empty stomach.

How can I decide which IF schedule is right for me?

The only way to know is to try. There truly is no right or wrong way to do intermittent fasting. The important thing is to listen to decide what fits best in your lifestyle. Consider what your daily/weekly schedule looks like. Is it possible for you to limit your calorie intake to fit alternate-day fasting? Can you stick to a 8-hour eating window while eschewing food the other 16? Ask yourself these types of questions and try one method for a few weeks and see how it works.

When is the best time to fast/break fast?

This is generally a choice you can make for yourself based on your lifestyle and daily schedule. However, if you’re trying intermittent fasting with a goal of weight loss, it’s important to note that our bodies are more metabolically active in the morning. That would make 7am – 3pm a good window for eating to help support that goal.

Otherwise, just consider your lifestyle. Do you want to eat dinner with your family? Do you like to go out with friends in the evening?

Who should not consider IF?

For the most part, IF will work for anyone. But if you are pregnant, nursing, or trying to conceive, this may not be the time to make a drastic change to your eating schedule.

Importantly, if you have an eating disorder, intermittent fasting is definitely not the right choice for you. I encourage you to work with intuitive eating and be very kind to your body. This is a restriction after all, and even if you’re light and playful, this is not a good path to go down.

Is it okay for a person with diabetes?

Absolutely. Intermittent fasting can be a very successful protocol for people with diabetes. Before you start, be sure to talk to your doctor, especially if you are on medication. Your prescriptions will need to be adjusted for fasting periods.

Can my children/teens do IF with me?

Children and teens are growing and have different energy needs than most adults, so it is important to make sure they are getting the calories they need to be healthy and for their bodies to grow and change the way the need to.

If your child or teen is interested in trying intermittent fasting with you for whatever reason, I recommend the 12:12 method, and not going lower than that for them.

How does intermittent fasting work with training?

The short answer is that it can work very well, if you make it work for you.

If you are planning for a workout that lasts up to an hour, it’s safe and still effective to go into that workout during your fasting time. A pre- or post-workout snack is not necessary for that workout to still be effective.

If your workout will last 2 or more hours, you should schedule that during your eating window, so that you can fuel before and after that effort.

If you are hitting the gym and trying to bulk up, it’s important to schedule that workout during your eating window as well, so you can have that post-workout snack to get nutrients to those muscles.

How long can I do IF?

Intermittent fasting can be a long-term lifestyle choice for almost anyone. The benefits, both short-term and long-term are incredible, and there is virtually no downside. A lot of people love the structure it brings to their life and have done it for years.

If you find yourself months or even years into intermittent fasting, consider switching things up. If you’ve been doing 18:6, try going to alternate day fasting for a few weeks, for example. Keeping it fresh and keeping your body adjusting can maximize the benefits of intermittent fasting. Have fun, and try new things!

Ready to Start Fasting?

I’m the first to admit that the idea of fasting can seem a bit crazy—even scary.

… What if I’m hungry all the time?

… Will it leave me tired and weak?

… What will other people think?

Intermittent fasting can take away many of the concerns around fasting because it offers so much flexibility, while at the same time acting as an effective health tool.

If intermittent fasting sounds interesting to you, give it a one month try and see what you find. It could but just the boost you need to drop a few pounds and jump start your long-term health.

About the Author: Pamela Fergusson is a vegan Registered Dietitian with a PhD in nutrition. She and her husband Dave have four children, and she loves to speedwalk ultramarathons. Read her nutrition blog and find her on Facebook.