40 Days of Fasting (Intermittent)

Actually it was 43 days before I got my blood test and 47 days before I finally cheated. My plan at first was 30 days, then figured who fasts for 30 days? 40 days has more history, then I figured I’d try to do at least one more day than Jesus, then I had to wait for an appointment for my blood test. The lady at the lab asked if I had been fasting and I said, “heck yeah, for 43 days!” After my blood test I thought about hitting Taco Bell, but I wasn’t that hungry so I figured I’d keep fasting. Today I’m 78 days in with just 3 cheat days, but I never ate before 5 pm the first 47.

It all started (for me) when I read, and blogged on that paper about the calorie restricted (CR) monkeys having MORE muscle mass than those who ate as much as they wanted. I was like what? That’s the opposite of what I would have expected. Guessing as to why I did some follow up research on Pub med and found out that both young and old CR monkeys had increased testosterone as well, which is partially explanatory, as was another paper that found less muscle cell apoptosis (programmed cell death) in CR animals. Looking through the animal research, with human studies tending to be in agreement, caloric restriction was a very healthy thing that basically slows the aging process and helps with a plethora of metabolic illnesses. More reading led me to papers that found intermittent fasting (either eating every other day), or time restricted feeding (eating only certain hours of the day) had similar and sometimes greater health benefits as caloric restriction. Some of these benefits were both neurological or musculoskeletal which I thought could really help a lot of my physical therapy patients. In my physical therapy practice I do a lot with exercise and EMS, which I know does a lot of good treating people from the outside. However with calorie restriction, for which intermittent fasting seemed the easiest way to go about it, I thought it could do a lot of good to cure them from the inside, particularly if combined with my largely exercise/EMS programs. Always wanting to test something new, I wondered how hard was it to do in practice, and what would it do to me?

So April 17th I wrote my monkey blog about eating less for more muscle and on April 20th I started healthy intermittent fasting. I had read the wiki on The Warrior Diet years ago, and had tried it on and off, skipping lunch from time to time (I already skipped breakfast) but on April 20th I figured I’d start it strict, actually read the book, and see what could happen. Had I read the book first I might not have tried it. Although I thought the basic premise was sound and a number of his observations agreed with my own, in the book the author Ori Hofmekler said he didn’t really fast during the day, but just ate small meals “underfeeding” to later “overfeed” after 6 pm. A lot of his claims came across pretty pseudoscientific and he recommended the sale of a lot of his own supplements, and per the order form in the back of his book, his supplements cost a total of $416 plus shipping. The thing that appealed to me about the Warrior Diet was not having to worry about eating at all during the day, so I was a bit disappointed. Later reading the criticisms of the Warrior Diet on amazon.com someone mentioned the Fast-5, written by Bert W. Herring, MD. Best of all the Fast-5 book is FREE, simple to follow, there were no supplements to buy, and it really was fasting. I’m currently reading Martin Berkhan’s leangains.com blog, in which he recommends an 8 hour eat and 16 hour fast phases, geared towards bodybuilders trying to lose fat while maintaining or gaining muscle. It’s not exactly my emphasis but is great resource for research and rationales regarding intermittent fasting. For some star appeal, 8 on 16 off is what Hugh Jackman did to get in shape for Wolverine. For now the Fast-5 suits my personality and lifestyle so I plan to stick with it, slightly modified, for the time being.


My last body fat test was 6 months prior to the fast that was on 9-29-14 as I was wrapping up my year of electric muscle stimulation self experiment and I was 183 lb and 7.2% body fat. The last time I weighed myself before the fast I was 179 lb. May 5th, (16 days in) I figured I should measure where I was at and I weighed 179 lb at 7.4% body fat. On 6-1-15, 43 days in I weighed 183 lb with 6.8% body fat and felt pretty jacked. Skin-fold tests have a good 2% error range and my body weight in a day will fluctuate as much as 4 lb, but I feel pretty good about saying at the end of 40 days I didn’t lose any muscle, and did seem to measure a bit leaner. I did EMS workouts only one weekend over that month because I was worried I was losing muscle, and I did a couple hard (for me) interval cardio workouts on the Stepmill to see how that affected my hunger level (surprisingly they didn’t), but otherwise I was pretty sedentary because I wanted to see what the diet did by itself.

My blood test results were more dramatic. A couple months prior to starting the fast (2-22-15) I had a physical, and I was yet again told I had high cholesterol, so I was curious what IF would do for that. Since I had just blogged on caloric restriction and testosterone levels, I wanted to see what healthy intermittent fasting did to mine, and I was glad to see that my prior blood test checked my pre-fast testosterone. The results were:

[table id=4 /]

So boom! After 40 days of fasting my total cholesterol dropped 41 points moving me from “high cholesterol” to “good cholesterol.” HDL cholesterol dropped 7 points (so that stinks) but LDLs dropped 35 points still  improving my cholesterol/HDL ratio. My free testosterone increased 6.2% and total testosterone increased 25%, just like the monkeys!

How hard was it? A lot easier than you might think. The Fast-5 recommends you start by skipping breakfast for some time, then when you’re used to that you skip lunch, start eating after 5 and you are on your way. I have skipped breakfast almost every day for the last 20 years (to the chagrin of everyone fatter than me who ‘knew better’ but I digress), so all I had to do was start skipping lunch. Also I had played around, inconsistently, with what I thought was the Warrior Diet for a couple years so skipping lunch wasn’t unheard for me so I might have had an easier time getting started than most. In the book the 8 Hour Diet (which turned out to be a watered down version of the leangains.com diet) the author interviewed one of the intermittent fasting researchers, who said if the subjects lasted 2 weeks, they were all able to stick with it. That sounded reasonable per my experience. Fasting got easier the longer I did it and having a 30 day, and later 40 day goal, gave me something to stick to. Since then I have stuck with it because I like it.

I should point out that the Fast-5 diet allows eating in a 5 hour window from 5-10 pm, but a handful of times I would eat as late as 11 pm or so. Sometimes I would come home from work, have a high carb meal, fall asleep, wake up at 10 pm and still be hungry.  If that happened I ate more that night rather than make myself wait till the next day, so at worst my longest eating window was maybe 6 to 6.5 hours rather than 5. However, I was real strict about waiting till 5 pm to start eating each day.

Also what I thought was interesting about the 8 Hour Diet book, was that it said pretty much all the researchers testing fasting on animals and people were fasters themselves and they all looked great. And that was something I wondered about that you didn’t see written about in the objective research.

What I like about fasting:

  1. It’s easy! In fact it’s better than easy! You get to stop doing things you were doing already, like preparing breakfast, lunch, and snacks.
  2. It’s free! In fact it’s better than free! Not only does it cost nothing, you save all the money you were paying for breakfast, lunch and snacks.
  3. It saves you time, eating and preparing.
  4. You don’t have to count calories.
  5. You don’t have to think about food.
  6. More energy all day (very noticeable), and for me seemed to improve especially around 30 days or so.
  7. My BP dropped from borderline high ~140/90 to normal ~120/80.
  8. My cholesterol dropped A LOT!
  9. At night you can eat whatever you feel like.
  10. At night you can eat as much as you feel like.
  11. After a while I noticed myself getting full faster, to a point where I wasn’t eating much more at night than usual, and I might have been eating less. So I think my stomach actually shrank, which I started to notice after maybe 15-20 days or so. I didn’t notice that with inconsistent missed meals prior to starting the my strict fasting program.
  12. You know how food tastes really good when you are really hungry? It’s like that every day.

What I don’t like about fasting:

  1. Sometimes you feel hungry (especially when others are eating, or if you are bored) and you want to eat, but I imagine this is no worse than any other diet.
  2. It’s a bit anti-social, I’d be out with friends and everyone would go to a restaurant, so to be social I would go along, but it’s a little weird when they are eating and you aren’t. In time I got used to that too and I found myself ordering take out so I could just eat the food that looked best later.

Things I noticed about fasting:

  1. The things I liked list is a lot longer than the things I didn’t like.
  2. Ordering healthier appetizers. I started ordering brussel sprouts. I hate brussel sprouts, or used to, but they taste better now. So blander foods seem to have more flavor.
  3. Super high fat appetizers, onion rings and fried calamari started to make me feel sick. So that’s weird. I used to love that stuff but fasting seemed to make really high fat foods unappealing. I remember in the movie Supersize Me, Morgan Spurlock said he felt sick when he first started eating McDonalds and I thought that was a little over the top. I thought he was playing it up for the film because I had never felt sick after eating high fat foods. Now I think (coming from a vegetarian diet) he was legit.
  4. A container of spun honey I bought lasted me better than a week. Just a couple spoons satisfied my sweet tooth, when before I would have eaten the whole thing. I never enjoyed moderation before.
  5. I can workout in the morning (20 minutes of hard Stepmill intervals) and be fine, hunger-wise until evening. I miss my post workout carb loading interval so it may not be ideal for sports performance and recovery, but I was no more hungry than usual and I imagine a burned a fair amount of fat.
  6. Starting to eat at 5pm instead of 6pm means you catch all the happy hours.
  7. At the store at the checkout, I’m not tempted to buy sweets cause it’s not 5 pm.
  8. Fasting gives you willpower. People say they have trouble not eating, but this just gets you used to it. People who know me know I had no willpower whatsoever with regards to food. In fact, fasting is the first “diet” I have ever attempted short of carrying around a cooler in college to make sure I ate 5000 calories a day to gain weight for weightlifting. Generally I would eat cookies, candy, and chips till they were gone, it was what I was used to. In hindsight the things that saved me from obesity was my fair amount of residual muscle mass from prior bodybuilding and residual weightlifting, and the fact that I always skipped the least important meal of the day, breakfast.
  9. If you are busy you don’t feel that hungry, when you are hungry it’s a feeling you are used to and you know it’s healthy so you don’t mind the feeling as much as you used to.
  10. If I had something to do at 5 pm, it was no big deal to keep waiting. A lot of times I would stay after work talking to people, or would go home and surf the web, and not start eating till 6:30 or 7 pm.

Other thoughts

  1. Intermittent fasting might share benefits with various cleanses/detoxes talked about with alternative-med/new-age folks, but it’s like a clense/detox you do every day.
  2. Intermittent fasting might share benefits with vegetarianism.
  3. It probably helps mentally to know that you aren’t abstaining from anything, you’re just waiting, and in my experience that’s enough to get you past all the midday temptations and I just felt like making better food choices later on. Instinctively or cognitively thinking that if you are only going to have one big meal a day, it probably shouldn’t be junk.
  4. I felt pretty stoic around 35 days into the fast, and when I see people eating or snacking it makes me think they are weak willed. That’s not exactly pro-social but I recall hearing that anorexics like the feeling they get when depriving themselves and not giving into their impulses. So I wonder if the feeling is similar and if time restricted feeding would be a treatment option for those with eating disorders. They would get the satisfaction from the deprivation (which I found one study which showed they do in fact get that satisfaction) but they would still be able to so called binge, each and every night.
  5. The big test was my last official 41st day, where I went to a party at 3:30 with awesome food and I couldn’t start eating till 5. Actually it made for some good conversation as a lot of people were interested in why I wasn’t eating, so I showed them my monkey photos, talked about healthy intermittent fasting, which people seem genuinely curious about. So at 5:00 I started eating, it was great, and I didn’t cheat on my fast. I was thinking if I had been on a typical calorie restriction diet I either would have been miserable all night or I would have cheated.
  6. Also I thought with the Fast-5, where you eat at night, that if you like food, every day ends on a good note. So you always go to bed feeling full and satisfied vs calorie restriction, alternate day versions of intermittent fasting. I had recently read something somewhere about a psychological principle that however the end of something goes the better you feel about it. So the better the end of a workout, a physical therapy session, a phone call, a relationship, etc. the better you feel about it, even if the beginning and middle were tough. Basically a psychological principle of all’s well that ends well. So the cool thing about the Fast-5 is that regarding food and satiety, every day ends well.

Going Forward

I plan on sticking with the Fast-5 but I figured I’ll let myself cheat once a week in a social situation or if I just feel like it. However in the almost 40 more days it took me to get around to organizing these notes, usually I don’t take my cheat day. I think because I feel better fasting, but lazy and weak willed if I cheat.

I’ve started lifting weights pretty hard to see what I can do with my extra 25% of testosterone and see I can gain back muscle on it. So far it’s going well and lifting on an empty stomach is no big deal, nor is not eating afterwards. It’s likely not ideal, as a number of bodybuilders and Hugh Jackman are making use of an 8 hour eating/16 hour fast and getting great gains by having a pre-workout meal then loading up afterwards, but I want to see what happens if I stay with my 5-6 hour window, at least for now.

So overall, the healthy intermittent fasting was everything it was said to be; healthy, decreased blood pressure, decreased cholesterol, fat but no muscle loss, increased focus and energy, increased testosterone. It was a little unsocial, but if you are a social person and you live in America and you want to eat everything you want when your friends want you to, well, then you’re going to be fat.

Thanks for reading my blog. If you have any questions or comments (even hostile ones) please don’t hesitate to ask/share. If you’re reading one of my older blogs, perhaps unrelated to neck or back pain, and it helps you, please remember Spinal Flow Yoga for you or someone you know in the future.

Chad Reilly is a Physical Therapist, obtaining his Master’s in Physical Therapy from Northern Arizona University. He graduated Summa Cum Laude with a B.S. Exercise Science also from NAU. He is a Certified Strength and Conditioning Specialist, and holds a USA Weightlifting Club Coach Certification as well as a NASM Personal Training Certificate. Chad completed Yoga Teacher Training at Sampoorna Yoga in Goa, India.

14 thoughts on “40 Days of Fasting (Intermittent)”

  1. Hey, Chad. Great post, as usual.

    Today is my first day on the Fast-5 diet. Reading your notes convinced me to give it a try.

    I’ve experimented in the past with ultra low carb dieting – eating less than 30g of carbs per day, not eating until (but no later than) around noon (to avoid catabolism) and having a cheat night once per week to increase fallen leptin levels from the 6 days of low carbing (this is supposed to help burn fat). I got used to skipping breakfast very quickly and soon after that stopped craving sugar during the week. However, I noticed that after my cheat night (eating basically anything I wanted post-workout for up to 8 hours – limiting fat a bit to allow for the highest insulin spike possible and keep calories somewhat controlled) I would have put on all the weight I felt I had “lost” during the week. In the first few months of this type of dieting, I kept making adjustments to things like nutrition timing, workouts, etc hoping that eventually, the scale would reflect that I had put on some water from the cheat night on the following day when I resumed low-carbing but that every week or two, this number would be smaller. OR that I would eventually notice that I had gotten much leaner AND had put on a modest amount of muscle – which I felt would explain the constant scale weight, too.

    Long story short, on this diet, I always seemed to look the same. I got really confused when I started consuming carbs every work-out day and then eventually even on non-workout days and didn’t put on any weight (the only noticeable difference being that I did seem to have much better training sessions when I was all carbed-up). The only way I would begin to notice some fat gain was if I gorged myself every day for at least 4 days without training at all – but that seems obvious. So, I thought: what the hell? I thought carbs played such a huge role in fat gain/loss!

    I think the worst part of it for me mood/discipline-wise was that on the day after each cheat night, I felt incredibly deprived and my cravings were extremely difficult to cope with. I would push through most of the time but, it was often very unpleasant – I felt like a starved wild animal that had been given a tiny taste of blood and all I could do was think about how much I wanted to eat heavily again. I’d say that it would have been worth all the mental anguish if I had actually ever seen the results i was looking for.

    I realize now from reading your notes that probably the reason I didn’t gain a whole lot of fat from when I started to eat carbs at will is that I tend to eat heavily exclusively at night and I never stopped skipping breakfast. Now I’m excited to see what happens when I skip breakfast AND lunch and only eat between 5-10.

    I have a couple of questions for you. Please feel free to direct me to other posts of yours if you have already addressed these questions elsewhere.

    1. Are there any foods/beverages you avoided at all on the Fast-5? If so, did you do this for any particular reason?

    2. I’ve always heard that eating fat in conjunction with carbs post-workout stymies insulin spikes. Would you recommend holding off on fat until later in the night to avoid this possibility on work-out days or do you think that’s totally unnecessary?

    3. Is there any reason to avoid black coffee in the morning? As far as I know, it plays some role in cortisol production but I don’t know if that would be good or bad with respect to this diet. I only know that it helps to suppress my appetite by reducing the effects of ghrelin (stomach growling, nausea, etc).

    4. I plan to do lots of walking (I never run) during the day at my treadmill desk, lift weights starting at 3pm at least 4 days/week, and do EMS workouts when I feel like it. You mentioned that you avoided EMS because you didn’t want to lose muscle and that you didn’t lift because you wanted to see how the diet worked on its own. I’m not really worried about seeing how the diet works on its own because I’m not “researching” it to help people as you did. But, I am hoping to gain a bit of muscle while on the Fast-5. Do you think the plan I just mentioned would help me do that?

    5. Lastly, in the past, I have noticed that restricting myself to about 1200 calories/day (about a 30% caloric deficit from my maintenance intake) is the only way I lose any amount of fat. It’s just been historically difficult for me to maintain this because it’s a huge pain to count calories. I would usually count calories through macronutrients, if you will. In other words, I’d keep track of how many grams or protein, fat, and net carbs (subtracting fiber from carbs) I consumed in a day and made sure that the total grams I consumed in macros was equivalent to 1200 calories – this allowed me to see where my calories were coming from. Portioning everything out gets old fast. Especially since I cook for my husband and our roommate and typically add lots of ingredients to my meals for flavor that I would then have to count out to make sure I wasn’t getting more than 1200 calories (or, rather, I’d have to make sure I wasn’t getting more than my allowed 150g/protein, 70g/fat, and <30g/carbs). But, since that's about the amount of calories I feel I can consume in a day and see a downwards trend in body fat, I'm worried that I'll blow that number right out of the water on a diet like the Fast-5 since I love to eat. Then again, maybe the reason it has been so hard to stick to around 1200 calories/day is because I used to spread those calories out over an entire day. So, I don't really have a particular question here – I would just really like to hear your feedback on this concern of mine.

    Thanks for reading!

    • Cool Bridgette! I’ll be interested to know what you think. How well it works and how easy it seems. I would caution that though I thought the Fast-5 was easy and I like it, it is one of the more austere ones, with the leangains.com 8 on 16 off maybe being easier to follow. So maybe keep that in mind as a plan ‘B’ if it gets rough. I know Martin from leangains said he usually starts women off on a 10 hour eating phase, 14 fast phase because they tended to have more mood issues than guys, and they if they did well he would shift them to 8-16. I’ve been fasting for 80 days now and he’s been doing it since 2006 so I expect he knows what he’s talking about. That said the Fast-5 was written in 2005, so eh, follow your heart and let me know what you think. As for your questions:

      1. I ate whatever I felt like after 5pm, literally whatever I felt like. Lots of pasta, but now I’m trying to eat more protein and less carbs just because the carbs put me to sleep. Before 5pm I didn’t eat or drink anything with any calories whatsoever. I drank a lot of water, coffee, and tea without sugar or cream.

      2. I don’t know. I would think you would want a lot of everything post workout. In the leangains guide Martin says:

      “Generally speaking, carbs and total calorie intake is highest on training days. On rest days, carbs are lower and fat is higher. Protein is kept high on all days.”

      That said, I eat pretty much the same things whether it’s a training day or not and though I’m making efforts to eat more protein, I’m still not counting anything. I have no idea how many calories or grams of anything I’m eating in a day. I’m too lazy to want to know, and the diet still works, which is what I like about it.

      3. I think I drink about a pot of black coffee most mornings. I don’t feel like I have to, and I don’t drink it on weekends, but at work I do. I think it does suppress the appetite like you say and I think every author from every book on fasting I have read says they drink coffee.

      4. Since I started lifting, 30 days ago or so, I have gained back a lot of strength, maybe gained 5 lb, but it’s been hard to keep gaining. Probably the Fast-5 isn’t the best to gain muscle on. 8-16 seems to be what all the bodybuilders are doing. I’m still wondering what I can do within the confines of the Fast-5-6 though.

      5. When I first started I ate a lot for dinner but probably not more than usual, however after a while I noticed I got full faster and was throwing away a lot of what I cooked because I just couldn’t finish it. So if you are like me overeating during your 5 hours might not be a problem at all, and likely less of one as time goes on. And sugar/fat cravings are gone. I didn’t feel like I was addicted to it, but now I feel like I was and the Fast-5 really made me lose those cravings. It was kind of weird. Unfortunately other than reading about it, the only person I personally know that tried it and stuck with it is me. I tell people about it all the time, because I really think it’s the easiest version of a healthy diet if you live in ‘Merica’. But most people just think I’m nuts for doing it, or they think it’s something they could never do. I know a few at least that are trying it since I wrote my blog so I might be a better writer than talker. So definitely let me know what you think. If a bunch of people try the Fast-5 and say they like it then I’ll probably recommend it. If most say it’s too tough I might make the 8-16 my go to recommendation.

  2. Can one drink a 4oz glass of red wine with dinner? I am very interested in this. Dr borden was my mentor and sent me your blog. Very interested.

    • Is this THE Mike Burgener from Mike’s Gym? If so I remember you from NAU and I think I still have one of your T-Shirts, “God Made Weight Machines to Keep Geeks off Barbells” and I’m honored you liked my blog.

      As for the wine I have not seen any research that combines the health benefits of moderate alcohol consumption with that of caloric restriction and/or intermittent fasting. However I would expect the health benefits of each would be operating by different means and would thus be additive or at least partially additive. I couldn’t imagine one would subtract from the other. So I think it’s probably better if you DO drink a glass of wine with dinner. If it were me I’d drink two.

      I did a fair amount of research on the effects of alcohol consumption a few years back and the best conclusion I found was that there was a dose response relationship with the benefits of alcohol, up to a point, beyond which the negatives started to outweigh the pros. Based mostly on body weight the sweet spot for alcohol and health was two drinks per day for a man, and one a woman, being the most healthy. Interestingly, in the really early papers researchers thought it was the tannins or oxidants in the red wine that was improving longevity, and I remember some company started marketing pills with grape extracts or something. However in later research they learned it was the alcohol itself that provides the bulk, if not all, of the health benefits. So today I drink a variety of drinks with dinner, sometimes a couple glasses of wine, sometimes beer, currently Johnnie Walker Black Label.

      Anyway, I know you know your stuff, so if you try intermittent fasting I would love to hear which version you like and your experiences with it.

  3. I am the mike burgener you know. I have a very interesting story you might like to hear. If you could send me your e mail we might be able to discuss and see if it would be appropriate and appreciated.

    I am going to try the fast-5 or 6. I did this inadvertently 20 yrs ago and not on purpose and was very successful eating chips, drinking beer and anything else. Lol. Weighed 175.

    • Hi Mike,

      I used to do Olympic lifting, coached by Rich McClure at the time and I remember you would bring your family up to lift with our team at NAU. I’d love to hear your story. It’s funny, a lot of people I talked to said they used to do things real similar to the Fast 5-6 and did great with it. Then later some nutritionists, who were probably shills from Kellogg’s corporation told them breakfast is the most important meal of the day, and they should have 5 more meal on top of that. Email incoming.

  4. Hey Chad!

    Today is my 23rd day on the Fast 5 and I love it! I don’t really see myself ever returning to a typical eating style. I thought I’d share some of my observations so far.

    1. When I first started the diet (July 7), I weighed 174. I lost 6 pounds within the first 10 days without doing any walking (was still nursing a nasty ankle sprain). I was taking +/- 10g creatine everyday and didn’t bother limiting my carbs at all on non-workout days. Normally, I lose weight very fast on an ultra low-carb diet but, it’s all water and I put it right back on as soon as I eat carbs. So, I was pleasantly surprised that I had lost 6 pounds and that it was staying off in spite of paying no attention to my carbs or caloric intake.

    2. My weight has stayed at 168 for the past 13 days. Not discouraging since, as I said before, I would normally have gained back any losses by now. Plus, I’m on day 1 of my cycle and I usually start to gain weight around day 20 and don’t really lose it until after day 5. Also, I’m sure some of that initial drop in weight was water. I believe it’s only about a pound of fat that you can lose in a week, typically. It might also be that I simply won’t drop much more fat without more walking – which, I started doing seriously again yesterday. If that doesn’t seem to help after a couple of weeks, I might eliminate something from my diet each night – like skip that extra serving or something. Not too worried about it, though.

    3. My cravings have all but completely subsided. If I find I want something during the day, I just remind myself I can totally have it in just a couple of hours! It’s that simple; I just wait a little while. Not hard. I’ve told a couple of my friends I’m doing this and they say, “Oh my god, I could never do that! I love food too much!” I love food, too. A lot! But, can’t help but think the only reason they would find this to be THAT challenging is that they have very low frustration tolerance. All you have to do is wait until the evening and you can have anything you’re craving. Doesn’t seem that hard to me. And it’s not because I’m special – it doesn’t seem to be that hard for anyone who sticks with it longer than a couple of days.

    4. Fast 5 helped me control my PMS eating habits this month. Personally, PMS eating has always looked a lot like binge eating to me and Fast 5 helped me make sure I didn’t do that during the day. In turn, I probably saved myself a few thousand calories last week alone just by waiting to eat until after 5. I cannot overemphasize how much easier it is to not eat for a long time than it is to eat just a little bit!

    5. I haven’t really wanted the cheat nights. I had a cheat meal around 11:00pm one night when some friends were over (a few beers, some waffles) but, I didn’t feel I HAD to have it – I just wanted it – and I didn’t miss the excess eating the next day.

    6. I’ve been getting more work done during the day. I’m not as concerned with what I’m going to eat/if I should eat during the day. This not only saves me time on meal preparation/consumption but also helps clear up some head space so I can focus on getting things done. Waiting until 5 every day also gives me something to look forward to WHILE I’m getting work done. I didn’t expect it to feel like a reward but, it kind of does. I am happy I’ll be eating soon every day around 4pm and I’ve been revisiting my love for cooking and experimenting with flavors, too. 🙂

    7. I lift regularly and find that knowing I’m going to eat at 5 helps me keep my workout timing consistent. I usually start heading to the gym around 3:30. I train until around 4:30/4:45, come home, shower, then break my fast with post-workout nutrition. My workouts have been easy compared to when I’m training in a keto-state. No lightheadedness, plenty of energy. I haven’t noticed any decrease in strength or muscle mass whatsoever.

    8. I’m much kinder to myself when I eat. I don’t feel pressured by every calorie or every gram of carbohydrate I consume. I just know I’m going to eat until I’m full and I’m content with that. I also don’t feel like I’m in a hurry to eat everything I possibly can because it might be another week before I’m able to enjoy some of my favorite foods. I’m not frantic like I was on Carb Nite. I know if I didn’t get to eat something I really like on any given night, I can just have it the next night and it’s no big deal.

    9. I’m not as hungry during the day. I’m sure the black coffee is helping a great deal with this.

    10. Finally, my acid reflux is getting better. Since I’m not in such a hurry to stuff my face with “what’s allowed” for the night, I find I eat until I’m full, then stay up and watch a show, read, write, or go for a very slow-paced stroll. Often, I don’t want anymore food by 9pm. I’m just not as concerned with it as I used to be. This gives me a whole two or three hours of not eating before I go to bed which really helps my digestion. I suspect this will have nice long-term effects on the acid reflux I was having. To be continued.

    I haven’t taken my body fat% since a couple of days into Fast 5. I’m giving it the full 40 days before I do that. I will let you know what the results are!

  5. Good info. Started yesterday.

    18hr fast 6hr eating window

    Window starts at 5:00pm Workout at 9:00pm Final meal at 10:30pm.

    Goal: Lose some weight while maintaining strength. I will also try to see how explosive I am in jumping during fast period.

    Will let you know how it goes when we meet in 20 days.

  6. Chad,

    I’ve been reading a lot about different IF protocols. It seems like there are numerous benefits! I’m an endurance athlete and do moderate to high intensity cycling anywhere from 12-15 hours a week. My challenge is that I experiment with IF on days I ride late or off days but it’s not doable on ride days (here in AZ we ride early). I recently read about fast 5 and if I understood it right the window could be any 5 hour period of the day. Have you tried Fast 5 in the morning or mid day by chance? This may work for my endurance sports if I eat lets say between 6AM and 11 AM – not sure if that would cause me adverse effects like sleep problems. Any thoughts would be appreciated. Thanks!!

    • Hi Jon,

      That’s a good question. So far, I am aware of no research that looks at the effects of intermittent fasting for endurance athletes. With bodybuilders there isn’t much research either, but at least there is a bunch of “broscience” that I actually think is pretty credible. However, endurance athletes not so much, or maybe I’m not as much in that loop. However, I still have ideas, that I would love for you to tell me what you think, or better yet, try out and say what happens. Then we’ll have our own broscience.

      You are correct about the Fast-5 being that you eat any 5 hour block that you want. I still love and recommend the Fast-5 to people, largely because the author Bert Herring gives away his book for free and doesn’t try and sell you on a bunch of other worthless supplements. I’ve been doing versions of it over two years now, but in theory I keep my window 4 hours or under and in practice I usually just eat one meal that might only take an hour, so mostly I’m doing the 23/1.

      While in theory you could make your eating window in the morning, I wouldn’t. As you surmised sleep problems are likely to be among them. I did a blog on how I thought most dietitians advise about when to eat is wrong and I stand by that. I sleep great on a full stomach and I have done a fair amount of overnight fasts in the last couple of years and those nights my sleep has definitely been disrupted. For me, not eating at night feels like I started drinking coffee at 6 pm and never stopped. Other reasons I wouldn’t eat in the morning, is that it makes evenings less happy. One of the things I love about the Fast-5 with a late window is that if I get hungry, I’ve always got that reward coming, so I’m never abstaining, I’m just waiting. With a morning window you don’t have that reward to look forward too. There are other reasons, but they mostly come down to the fact that a late eating window is psychologically more difficult. However, all these things are experiments of one, what matters is what happens on yourself, and in the last couple years I have done a lot of things with my fasting that maybe isn’t ideal, but I just wanted to see what would happen. I tell people dieting is a chore but fasting is an adventure as you continually test to see what happens and what works best.

      Anyway, these are my thoughts for an endurance athlete, not really being one myself. While there is as yet no research on fasting and endurance sports, there is some on ketogenic (low carb) diets and what they find is that when endurance athletes start a ketogenic diet, their performance immediately suffers. However, I think there are two papers, that found that if you stayed on the diet for 4 weeks, endurance was found to increase back up to baseline. I think they thought it was because your body shifted it’s hormones and enzymes around to match the current diet and became “keto adapted.” Thus able to better derive energy from fat than from carbs. So I think something like that maybe happens with intermittent fasting, particularly the time restricted feeding (TRF) variety like the Fast-5.

      Subjectively, when I did my first 40 days, after about 30 days I really started to feel good on it. I then began noticing the increased energy, and that’s when I knew I was going to stick with intermittent fasting indefinitely. It was towards the end of those 30 days that I started doing some intense (for me) 20 minute morning intervals on my stepmill and I did just fine, even though I did not eat till hours later in the evening. In the first couple weeks of fasting you may see a performance decrement, but half of that is probably mental, and once you get used to training on an empty stomach you’ll probably come to like it.

      Also, unlike with a ketogenic diet I don’t think you are really running low, or that low, on glycogen. In the last year I have been testing my blood glucose (just to see what’s really happening) and without breakfast I’m always higher (maybe 110ish) in the morning, with my blood sugar slowly dropping throughout the day. In fact, even if I eat a Sunday night, have high blood glucose Monday morning, that drops to the 70 by nightfall. If I skip my eating window Monday (thus fasting 44 hours by the time I eat Tuesday night) my blood sugar is still higher 100-110 Tuesday Morning. It’s like my body knows it needs to be ready for activity. Diabetics call it the dawn phenomenon, however I’m starting to wonder if it’s only known with regards to diabetics because they are the only ones testing their blood sugar. At this point, and I’ve tested it a lot, I only start to notice a drop in endurance (per my stepmill) and energy throughout the day if I have been fasting longer than 38-40 hours or so. So I expect if you get used to an evening eating window you’ll find it works just fine, but I think it would be something you want to do consistently every day, not just sometimes. Also it’s something I would test in the offseason and not before any important races. Definitely I’d love to hear you report back with what you try and what happens. I hope that helps and if I can clarify anything let me know.

  7. Hey Chad,

    Liked your post very much.
    Today is my 34th day of IF ( Eat 1 meal a day around 4.30 to 5 pm )

    Got lot of benefits .

    My question can this diet be done indefinitely, as have become very comfortable with it.
    I plan to do for 90 days minimum


    • Sorry I didn’t see this message until really really late. However, I absolutely think you can keep doing IF indefinitely. I’m coming up on 5 years now, having never stopped.

  8. Let’s bring this thread back to life! I’ve been inspired in many ways by this blog. Started my fast yesterday. I plan to do it for at least a month and reassess. Interested to see what happens while I’m recovering from a herniated L5/S1. I’m not looking to lose any weight as I’m already very lean. Very curious to see how my strength and exercise routine will progress. Perhaps when I’m healed and back to my tree service I’ll switch to the 8/16. Got a ways to go before I can lift heavy again and bulk up. I’ll post an update. Really appreciate your site Chad!

    • Hi Will!

      Thanks, this is one of my favorite blogs! It’s been almost 5 years but I’ve gone the other way. Instead of the Fast-5 or the 4/20 of the Warrior Diet, I’m just doing one meal a day. It’s like the 23/1!,lol. Interestingly, I’ve found I can bulk on anything if I want to. However, I’m not trying to get as big as when I was bodybuilding. However, check out the Spinal Flow Yoga instagram.

      I’m getting surprisingly good muscle gains with my SF5 program, which is all I’m doing now. I like it every bit as much for total body fitness as for spine rehab.


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