Intermittent Fasting - What It Is & Why You Should Do It

Have you heard of intermittent fasting?  It's a practice that is growing in popularity, with articles popping up all over the place. Maybe you know someone who's tried intermittent fasting, or you've even tried some aspect of fasting yourself.

Before you push it aside as just another "fad", let's look at what intermittent fasting is, what the benefits of intermittent fasting are, fasting safety, and oh so much more.

Stainless fork on a white plate and blue placemat under it

What is Intermittent Fasting?

Intermittent fasting is an ancient practice, in all major religions, that involved abstaining from food for set periods of time for the purpose of health and spiritual focus. My emphasis here is on the health aspect, but I also believe the spiritual focus is a worthy reason to pursue intervals of fasting on a regular basis.

I have been practicing intermittent fasting for about 8 months now.  The time frames for me have been to fast from supper to supper 1 day/week (so about 24 hours) and then fasting supper to lunch 2 other days (so more like 18 hours). The beauty of intermittent fasting is that you can pick any time frame (most of us fast 12 hours or more naturally from evening until we eat our "break fast").

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Benefits of Intermittent Fasting

Weight Loss

One of the biggest benefits of intermittent fasting is weight loss. Over the 8 month time period during which I have practiced fasting, I lost 40 lbs.

This was in conjunction with a low-carb, high fat diet.

Simplicity

I have found that fasting is more simple to implement than any diet.  It is free and simple to fast, because you simply don’t eat.  Most special diets have some complications that require time and money to figure out. Intermittent fasting does not require time or money, which greatly simplifies life.

Insulin Resistance, Blood Sugar, and Metabolism

Other key areas of health that are impacted by intermittent fasting are insulin resistance and blood sugar levels.  When someone is insulin resistant, their cells are no longer sensitive to insulin, (which normally works to move glucose into the cells for energy), so their body has to produce more and more insulin just for basic metabolism. In turn, their body doesn't burn fat for energy.

Fasting lowers insulin levels and stabilizes metabolism, which then allows the body to burn fat for energy and get rid of some of the extra fat reserves. I have read many stories of situations where fasting combined with a low-carb, high fat diet has resulted in the reversal of type 2 diabetes and often the person getting off medication. In my life, fasting has helped with insulin resistance that I have dealt with for some years now and wasn't aware that I had.

Slows the Aging Process

One last thing I want to mention here is that intermittent fasting can benefit your brain and help your body stay young longer.  Memory improves with calorie reduction and lower insulin levels.

Our bodies are constantly replacing cells that have reached a certain age. Increased levels of sugar, insulin, and protein can also interfere with the process of this cell replacement.  Fasting can help the body to clear out the old and damaged cells and then restore with new cells.

People Who Should Avoid Fasting

Pregnant and Breastfeeding Women

Pregnant and breastfeeding women are two groups of people who should not fast.  You have a baby to care for, unborn or newly born.  Either way you need your calories to feed and care for your baby.  Of course those should be nutrient dense calories of real food, so that mother and baby will be nourished.

Children Under 18

Children under age 18 are still growing and should not fast. They don’t have to be pushed to eat if they aren't hungry, but they should not be fasting as a practice. Again, healthy food is necessary to feed children's growing bodies.

Malnourished & Those with Eating Disorders

Those who are malnourished or underweight should not be fasting. This also includes those with eating disorders like anorexia and bulimia, as it can encourage those kinds of eating issues. If you're not sure if you fall into that category, ask a friend or family member if you are underweight or malnourished--sometimes it's hard for to be objective about your own body.

If This Is You, You Might Benefit from Intermittent Fasting

Overweight

Those who want to lose weight may find their weight loss goals finally stop eluding them. Weight gain and loss is not a calories in, calories model as we have been taught for years. It is primarily a hormonal issue with the hormone insulin being one of the primary factors in weight gain or loss. Fasting means periods of not eating and skipping at least 1 meal in a given day. Not eating lowers insulin levels and encourages the body to burn its fat reserves.

Insulin Resistance

Those with signs of insulin resistance could do well to fast. Insulin resistance is when your cells are no longer sensitive to insulin and the body produces more insulin to force the cells to use glucose in the bloodstream. This starts with high levels of insulin, which then leads to higher levels of insulin and the cycle continues to grow. If you don’t eat, your blood sugar levels decrease, and if your blood sugar levels decrease, then your insulin levels will also decrease.

This category and that of those who need to lose weight will most likely overlap. However, there are some who are insulin resistant and do not have any significant weight to lose. The only way to really check this if you are not overweight at all is to check your glucose and insulin levels via blood work.

There are several different categories of people who should be cautious about fasting and consult with a physician prior to fasting.  This includes those with gout, those taking medications, those with diabetes (type 1 or 2) especially if taking medications for those, and those with GERD (gastroesophageal reflux disease). Such people should consult with their doctor and should fast only with close supervision.

Will Intermittent Fasting Make Your Metabolism Slow Down?

People can get concerned about you when you fast, that you are starving yourself and putting your metabolism in danger. The problem with slowed metabolism is not for those who fast, but for those who count and cut calories daily.

For example, the person who cuts calories 1000 calories daily to lose weight may see a change in metabolism. Initially they will lose weight, and then once their body realizes that this is the new normal, the weight loss will stabilize, because the body realizes that the amount of calories coming in is not enough for normal energy expenditures. Because we cannot live at a deficit long term, the body compensates and will decrease the energy expended as well.

Our bodies do not shut down or slow down with short term fasting. Actually our metabolism increases, rather than decreases.

Our bodies will burn the energy we have available and then switch over to burning body fat. Various studies have been done which demonstrate this and show that fasting actually increases the basal metabolic rate.

During fasting there are also changes in hormones that contribute to metabolism. Adrenaline and growth hormones will increase to maintain energy levels and keep muscle mass from decreasing. (So you won't lose the muscle you have if you fast, because the body works to maintain that.)

Adrenal Fatigue and Fasting

Before diving into this category, let me say that I'm aware that there is debate as to whether or not adrenal fatigue is a real condition. However, for the sake of this argument, let's assume that it is, or at least that there is a situation in which the adrenals are overly taxed.

If adrenaline and growth hormones increase when fasting, is this a danger to those with adrenal fatigue?

There is conflicting information about what is safe for those with adrenal fatigue, and this includes the area of intermittent fasting.  After researching this, my conclusion is that  if you have symptoms of adrenal insufficiency or fatigue, you should proceed with fasting cautiously.

My advice is to deal with the fatigue first and go very carefully and slowly on the fasting end. If fasting makes you feel worse and increases the symptoms of your fatigue, then stop for now. Work on healing your adrenals with good diet and supplements and adequate rest. When you see improvement, possibly move forward on fasting.

Supplements that I've found to be of great value with adrenal fatigue are Vitamin C, adrenal support herbs (turmeric, ashwagandha, etc.), and magnesium. I take magnesium malate, which isn't hard on my GI system and works well. {Adrienne uses Magnesium Glycinate which does not cause digestive upset and is apparently well absorbed.}

Free 10 Day Fasting Challenge

If you would like to try intermittent fasting, I offer a free 10 day fasting challenge several times each year. We'll be fasting together as a group for 30 days, but you can choose when and how long you fast. I send out emails twice weekly with information and tips on how to focus your fasting, how to deal with problems like hunger, suggestions on eating when you are not fasting, and more on metabolism and insulin resistance. Free 10 day fasting challenge

I also have a guide to intermittent fasting for sale if you would prefer to get all the information in one shot and do this on your own. This is also available at Purposeful Nutrition here. I am offering a discount to those who read this blog for a limited time. If you use the coupon code {whole new mom} on the sales page you'll save $3 off the regular price.

Intermittent Fasting Book

What do you think of all these benefits of intermittent fasting?
Are you going to try it?

Sources:

https://www.ncbi.nlm.nih.gov/pubmed/16051710
https://www.ncbi.nlm.nih.gov/pubmed/25540982
https://www.ncbi.nlm.nih.gov/pubmed/23582559
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3670843/
https://news.usc.edu/63669/fasting-triggers-stem-cell-regeneration-of-damaged-old-immune-system/
https://www.ncbi.nlm.nih.gov/pubmed/2186256
https://www.ncbi.nlm.nih.gov/pubmed/8172872

Jennifer Dages of Purposeful Nutrition


Jennifer is a happily married homeschooling mother of 4 who lives in a small town in Pennsylvania. She blogs at The Entwife’s Journal and at Purposeful Nutrition.  She's also an RN who's working to build a health business through blogging, speaking, and health coaching.

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38 Comments

  1. So for over 20 years I have spent 85% of my life either pregnant or nursing. (Eleven kids, all of them late on due dates, plus I nursed each one for at least a year but no more than 17 months.) That has kept me from trying any kind of total fasting for any reason. However, due to having 11 kids, I frequently go till 11 am without food. That means I have done 16 hour fasts. ? I guess kids can be helpful to your health!

  2. I have embraced intermittent fasting (IF) as a way of life for the past few years. Not being a breakfast eater, I was unintentionally using IF as a normal way of life! I eat clean food prepared from scratch -- on purpose low in carbs-- using good quality fats daily. Fats like coconut oil, pure Olive oil, Avocado oil, and pastured grass-fed butter. My fasting (normal for me) schedule is 7pm to 12 or 1pm when I usually eat lunch to break my fast. I do, once in a while, eat a big farm breakfast, but that keeps me fueled until I eat supper. I also walk at least 5 miles a day at a fast pace (4.3 mph). I feel great and I've slimmed myself down in the process! This is a very manageable lifestyle. Oh, and my recent blood work for my annual physical looked great! 🙂

  3. This is an essential topic , I have endorsed intermittent fasting for the past year and lost 34#. This regime has included changing my diet once diagnosed as celiac, as well as increasing my activity only by walking . The daily goal is a minimum of 10,000 steps which I don't meet every day . It's not been easy but it has made me feel so much better ! No more sluggish feeling , and G.I. distress, which has been wonderful to experience, after 10 years of being diagnosed with IBS . Fasting gives your system a break which is much needed, given our highly processed foods we consume daily.

    1. How wonderful! Would you mind sharing how often and for how many hours you fast and if you had any thyroid or adrenal issues? Thank you!

    1. I have read this from 1 or 2 folks, but it has not been my experience. Others like Dr. Fung do not seem to think this is a problem. Perhaps your body is changing for some reason and something else is going on. You may need to cut back your fasting or make some changes. I would experiment with making some changes in the frequency and duration of your fasts and see how it impacts your sleep patterns.

  4. I've been practicing this for about a month and besides the weight loss (about 6-7 pounds) I feel great! I look forward to my fasting days. It has made losing those extra pounds not feel like deprivation but doing something positive for my health!

    1. How interesting! How much have you been fasting as in hours per day and days per week? And did you have any adrenal or thyroid issues?

  5. Dr. Mercola has been recommending intermittent fasting for quite a while now. He is saying the same thing as the article. I've been following him for a couple of years now. Thank you for the article, it's very interesting!

    1. I haven't been reading as much of his information but overall I do like his content. Thanks for the kind words!

  6. Great post! I have been fasting for the last 6 months doing 3 day fasts with the Miessence FAST product you shared above. I LOVE IT! The genius of the product is that you are still supporting your body during the deep detox that happens during a 3 day fast, are "feeding" your body mega nutrients from the grass juices, herbs and superfoods, but all the while keeping your body in fasting mode and staying within the parameters to technically be fasting (under 300 calories and zero sugars or carbs). Fasting is the most powerful health tool I have encountered and I'm so grateful to have found it. I crave the feeling.... its a wonderful thing!

    1. Thanks, Alison!

      I've been meaning to order and try the FAST. I think for so long I thought that fasting was something that wouldn't be good for me, but the information in this post and in the comments is really compelling. I have to look more into this. So you are only eating 300 calories per day for 3 days in a row?

  7. I've been diagnosed with adrenal fatigue, pre-diabetes Type 2, and other not-so-fun issues. I found that when I fasted (16-18 hours), I had more energy, my head would be clearer, my blood sugar would stay balanced, and other benefits. I'm definitely going to continue this practice a few days a week. I am very careful about what I eat when I go off my fast, and feel great almost all the time, despite my current physical issues.

  8. I'm a 57 year old male and started daily intermittent fasting (IF) 6 weeks ago at the suggestion of my PT (Fast 5, only eating between 5 and 10 pm, but eating anything that I wanted, including cookies and pasta that I have previously been deprived of) when I was 40 lbs overweight. I dropped 10 lbs in two weeks when I was only drinking water during the fasting time. I started drinking coffee with heavy cream during the fast and regained three lbs in the past 3 weeks. So for me, even cream broke the fast, so now back to only water. My PT says that I have to really fast (only water, black coffee or tea), cut the carbs and eat healthy most of the time to get to my goal weight. IF is not the cure to daily cookies, bread and ice cream. I find that if I break the fast early with a small healthy snack, I can't resist eating more until full. For me, it is all or nothing. When I get a hunger pang, I drink more water and just tell myself to wait until 5 to take the first bite. The hunger goes away very quickly. When I do eat I get full much faster than before so it is not like I'm eating three meals worth of food within the 5 hours, more like one meal that is a bit smaller than my before dinner and maybe a snack before bed.

      1. Hi Adrienne, I have been doing it every day for the entire 6 weeks except for two or three times that I broke the fast at 2 pm instead of at 5 (I was stressed and "needed" to procrastinate on something). The key is to keep busy until 5 pm. I plan to keep doing it daily until I get to my goal weight and then see what it takes to maintain. My PT has been doing it daily for over two years except for an occasional longer fast up to 30 hrs and has excellent blood labs. 19 hr fasting is enough for me, at least as a newbie.

    1. Hi Beth. I'm certain you can as you wouldn't want to get dehydrated but I will let Jennifer chime in as well.

  9. How does one do this when diabetic?????? I don't see this being possible when on insulin for diabetes.

    1. Hi Caryn,
      There are diabetics who do this, but it requires some close supervision over your blood sugar. I would recommend that if you want to try it, you talk to your doctor and possibly find a health coach or work closely with a nutritionist. You would need to be checking your blood sugar quite frequently throughout any fasting times. And you would need to be watching closely for the effects on gout and GERD. So please don't just try this without some extra help. It can be done, but there are potential implications that can cause further problems that you don't want.

      1. Check out the Youtube videos by Dr. Jason Fung, an endocrinologist from Toronto, Ontario.
        He has written two incredible books, The Obesity Code and The Complete Guide To Fasting.
        He has helped hundreds of his diabetic patients. He graduated from the University of Toronto Medical School at age 23!!!

        1. Not only can you, you should be drinking water. Coffee and tea are also acceptable, but without sweetener. And in some situations bone broth can be okay, although that is not a true fast liquid.

          1. The people I read don't seem to recommend decaf over caffeine. Many people recommend bullet proof coffee with cream and no sugar.

          2. I actually don't know. I am not a coffee drinker and never have been so I have no personal experience. I know all the "experts" in fasting communicate that coffee is okay to consume while on a fast. I find it kind of unexpected too,.

        2. I love Dr. Fung. I have both of his books and his information has been the motivating force behind my journey into intermittent fasting.

          1. Wow. I need to look into this. Very interesting. How does his work intersect w/ the concerns regarding those w/ adrenal issues. I would think that many w/ diabetes have adrenal issues too -- or perhaps not?

          2. I urge you to watch his videos - they are very informative and he is very funny. His videos can also be seen at Diet Doctor.com (I watched all of the videos in the first two weeks when it is free). His assistant, Megan, corresponds with a lot of clients by e-mail (if you don't live in the Toronto area). If you are lucky enough to live in the GTA, he sees clients in his office.
            https://thefastingmethod.com/
            (I am just fan of his work - I am not connected with his company!)
            Alison

          3. Dr. Fung is one person I researched about his perspective on fasting and adrenal issues and he is not concerned about that. He is the one who clearly has stated that fasting is fine for those with adrenal fatigue.
            Diabetes and adrenal fatigue don't necessarily go together although sometimes of course they will.

            1. Wow. This is so fascinating to me especially in light of my current practitioner recommending it to me (with caution).