What I’ve Learned from 2 Years of Intermittent Fasting

Adopting a philosophy of self-experimentation can make a tremendous difference in your life.

Choosing to experiment with new ideas can help you start a successful business. Choosing to experiment with sharing your work can launch your career as a writer or an artist. And choosing to experiment with different diets and workouts can help you discover a fitness and health strategy that works for you.

Of course, self-experimentation is exactly the opposite of how most of us want to approach things. We would prefer that someone hand us a one-page sheet with the answers to our problems and say, “Do this and you’ll be good to go.” Furthermore, if someone shares an idea that seems outlandish or weird, most of us would rather dismiss it than experiment for six months to see if it can actually work for us.

Just to be clear, I’ve made my fair share of mistakes and have dismissed ideas without trying them in the past. But in the case of intermittent fasting, which I’ll explain below, I’m glad that I decided to do some self-experimentation and see if it would work for me.

I’ve been experimenting with intermittent fasting for more than 2 years and this is what I’ve learned…

Intermittent Fasting: What It Is and How I Do It

Here’s a simple definition of intermittent fasting: you eat your normal amount of food in a smaller time frame. It’s not a diet, it’s just a pattern of eating that reduces your eating window each day to about 8 hours.

For example, I usually eat my first meal around 12pm or 1pm and then I can continue eating until my final meal at 8pm. After that, I fast until the next day at 12pm. That breaks out to about 16 hours of fasting and 8 hours of eating each day. I do this almost every day. (My guess would be that I do intermittent fasting 350 out of 365 days per year.)

I’m not going to dive into the details of intermittent fasting in this article. I have previously written a 3,000 word beginner’s guide to intermittent fasting and a lengthy question and answer guide on intermittent fasting. If you have questions about how it works and the science behind it, read those articles.

And if you want even more information, I was also interviewed on the Fat Burning Man podcast (here) and the Jimmy Moore’s live show about intermittent fasting (mp3 download here).

How I Feel After 2 Years of Intermittent Fasting

1. The biggest benefit of intermittent fasting is simplicity.

In an interview with Vanity Fair, President Obama described an interesting strategy he uses to make his life simpler. “You’ll see I wear only gray or blue suits,” he said. “I’m trying to pare down decisions. I don’t want to make decisions about what I’m eating or wearing. Because I have too many other decisions to make.”

What President Obama is referring to is a concept called “decision fatigue” and it can drastically impact your ability to make decisions throughout the day. I explained the science of decision fatigue in this article.

For the President, simplifying his clothing choices is a way to make life simpler and improve his decision making abilities. For me, intermittent fasting provides the same benefit. Eliminating breakfast and not thinking about food until 12pm each day has allowed me to reduce the number of decisions I make in the morning, thus reducing decision fatigue and increasing the willpower I have for the rest of the day. That means I have more energy to put toward doing work that is important to me.

One of the best ways to find happiness and success in life is to strip away the unnecessary things and focus only on what is needed.

With intermittent fasting, I have been able to increase strength, reduce body fat, and maintain good health while spending less time eating each day. If you can get the same results by making life simpler and only eating twice per day, why would you make life more complex by eating three, four, or five times per day?

2. Intermittent fasting is an excellent travel strategy.

I used to be annoyed by the lack of healthy food options in airports. This is especially true in my case because I’m looking bulk up and add good weight, so I need to eat a lot. Finding a sizable amount of healthy food is a tall task in most airports.

The solution? Treat your travel days as a fasting day and then eat twice as much good food the following day.

As an example, last year when I was flying back from Thanksgiving with my family, I didn’t eat that day. It ended up being about 32 hours between meals. That’s the longest I’ve gone on a single fast, but things worked out just fine and I avoided the poor nutrition of the airport.

3. So far, intermittent fasting has not hurt my long-term health.

I’m not interested in doing intermittent fasting if it sacrifices my long-term health for short-term improvements. And for that reason, I’ve kept a close eye on how I feel, how my body is responding, and whether my overall health is improving or declining.

Thankfully, I’m in better shape than I was two years ago, which is proven by my strength numbers in the gym.

And more importantly, a recent checkup with my physician has revealed that my blood work, cholesterol, and hormones are in check as well. And remember, this is after two years of intermittent fasting. (If you’re interested, my recent blood work results are here.)

Note: I think it’s important to clarify that I can only speak from my experience and I can’t promise anything with regards to how your body will respond to intermittent fasting. I know that, in some cases, women believe that intermittent fasting has thrown their hormones off balance. I don’t have any data on this and so all I can offer is my own experience. As with most things in life, your mileage may vary.

4. Intermittent fasting isn’t a magic pill.

In the beginning, I hoped that intermittent fasting alone would be a secret weapon for health and fat loss. It seemed like all of the experts were saying that if I changed what time I ate, then I would lose fat and gain muscle easily. That sounded good to me.

The reality, of course, is much different. I only started seeing the results I wanted when I combined intermittent fasting with a healthy diet of real, whole foods and consistent weightlifting.

Intermittent fasting is just another tool in your toolbox. Just as eating a healthy diet of real, whole foods is another tool. And exercising regularly is another tool. And meditating or doing yoga to reduce stress is another tool. And sleeping at least 8 hours per night is another tool.

You can’t live an unhealthy life in other areas and expect one thing to solve all of your problems, but you can slowly add a piece here or there, continue to self-experiment, and gradually develop a health strategy that works for you, your goals, and your lifestyle.

In fact, I’m convinced that you can reach your health goals without intermittent fasting at all (if you eat properly and train consistently). But I still think intermittent fasting is worthwhile because, as I said above, if you could get the same results while eating fewer meals and making life simpler, why would you add more meals and make life complex?

On a related note, if you’re looking for a simple way to eat healthier foods check out my “outer ring” strategy in this article.

5. I have no idea if intermittent fasting will work for you.

I can’t say whether intermittent fasting will work for you. All I know is that, as one piece of my overall strategy, it has worked for me. It works because it fits my lifestyle. It works because it is simple enough for me to not spend much energy thinking about it. And it works because it aligns well with my diet, which is mostly Paleo, and my training style, which is mostly Olympic weightlifting and other compound movements.

If you’re eating poorly or if you’re training for an Iron Man or if your job doesn’t give you the flexibility to eat your meals in an 8-hour window, then intermittent fasting might not be for you. And that’s fine. You can experiment with other ways to achieve your goals.

Where to Go From Here and What Actually Matters

No one will have the same experience as you — with intermittent fasting or with anything else — and that’s why you have to experiment on your own.

It might be easier to cite a study or follow the advice of some diet guru, but the only way to get results is to test, adjust, and repeat. As someone who often cites academic research in their articles, I have the utmost respect for science. But you can’t let a research study make choices for you. They can inform you, sure. But the only way to make progress and change in your life is to make new choices, take action, and make adjustments based on the results.

Whether it’s intermittent fasting or something entirely different, I hope you’ll choose to run your own experiments and see what works for you.


  1. Hi James,

    I’m intrigued with the notion of intermittent fasting, but every site I searched on the topic commented that intermittent fasting isn’t so great for women for a number of biological reasons. Can you recommend moderations that would make this form of fasting workable? Thanks very much in advance.


    • Changing the eating window is typically what women do to make it better for them health-wise. Typically, for men, it’s eat all your calories in a 4-hour window with one big meal during the day.

      For women this is usually changed to 8 hours with two smaller meals.

  2. Right on, James. Self-experimentation cannot be stressed enough!

    I will add that for me, I.F. has actually drastically increased my mental clarity in the mornings as well. Not only did I feel the difference, I measured it with quantified-mind. It is an interesting side-benefit that I had not been expecting!

    Be well!

  3. What advice can you help me with a friend of mine who is suffering with motor neurone disease,

  4. I started IF after reading your post about a month or so ago. While I’m not losing fat of building muscle mass (I’m not really watching what I eat: I eat generally healthy food, count my calories somewhat but I try not to focus too much on it since I have a history with BDD and I don’t weight lift, I just do bikram yoga and run for exercise), what I have lost is an obsession with food and eating. I have also gained food discipline. I used to snack late all the time and would feel awful for my early morning yoga classes, but now, since I have set 8pm as my drop-dead time for food, I rarely get tempted to sneak a 11pm cookie. I also have a better grip on my temper when I get hungry. I used to be so awful when I was hungry but now I can control it and I’ve learned to listen to my body more. And while I seem to have gained more than I lost with IF, I think overall, they were things I definitely needed in my life. I look forward to removing decision fatigue in my life too!

    Keep the posts coming! :)

    • Thank you for sharing Gayle! I like what you sat about feeling better in the morning (mornings are a big struggle for me) and I have the habit of late night snacking. Def going to self-experiment with this.

  5. I liked the article and since I am an (unofficial) student of human behavior myself, I find it interesting that you used decision making and willpower in the same context. Not saying they are not a good fit, I just never really thought of the possibility of increasing “willpower” by reducing the number of your decision making processes. Interesting concept, indeed. :)

  6. Once again James, I agree with every word in your article. I always say “I’m my own best guinea pig.” I’m 80 years old and a trainer in a gym. I’m in great shape and not on any medication whatsoever. I work out every day and use all the tools you mentioned, including a few others like Earthing/Grounding, meditation etc. I practice IF 16/8 6 days a week and a 24/0 on the 7th. day. It works right into my daily schedule as I cook all my own meals, and leaves all my mornings free. All my numbers are perfect and stay there without effort.

    I differ from you in only one respect; I use the Ketogenic diet rather than the Paleo. This diet toghther with IF and calorie restriction gives me all the results I desire with a minimum of decisions.

    Hope this comment will help others.


  7. Great article. I also tried this after reading about it in Mark Sisson’s primal blueprint book and when I spent two months on crutches after a knee op. It worked a treat for me, in that despite being pretty much house bound and on a machine at least 4 hrs a day, I lost a stone (14lbs) in weight. The first few days were ‘difficult’ while my body adjusted to the no food in the am but that soon passed. I’ve went back to old eating patterns and the weight went back on, so I’m back on it and aim to stay that way.

  8. I’ve tried fasting–not for me. Even going without food until noon is a severe trial that impacts my mood and energy negatively. However, I have reduced the “decision fatigue” by making breakfast very routine–oatmeal or Cheerios with milk and 250 ml of fruit juice at approximately 8:15 am keeps me going until lunch. I find that on Saturday, when my routine is different and I can’t eat until after nine that my body goes haywire and wants unhealthy foods NOW!

  9. I’ve found intermittent fasting has worked for me as well. I had played around with fasting for a whole day in years past, but found that just too difficult to do even once a month. I had been inadvertently intermittent fasting regularly when I was younger just because I’ve never been a breakfast person and like to sleep as late as possible. I really didn’t gain weight then, but assumed it was just because I was younger and more active and now I wonder if my eating habits were also part of it.

    I lost a fair amount of weight a couple of years ago, but using an App to track my calorie intake and exercise and I always had a high protein, high fiber breakfast since I’d heard for so long how you need a good breakfast. Then I sort of hit a wall and was looking for ways to lose a bit more without starving myself or spending more time exercising. I read about limiting your eating to an 8 hour window and then when I read your blog about intermittent fasting, I decided to give it a go. It worked. I even found I could increase my calorie intake a bit (10% or so) and still lose weight.

    For me it’s a really easy thing to do as our family tends to eat a good dinner fairly late and I’m not that into breakfast. I still find I have to eat healthy foods and exercise, but it’s a simple trick that helps me. I found that even if I only did it 3-4 days/week that I could still lose 1 lb/week or at least maintain my weight without starving myself.

  10. James,

    Another good and useful article. I heard your podcast with J. Moore and am glad you were able to do it – hope it helps your career. The most valuable part of this article for me is “self experimentation”, being open to testing yourself rather than looking for the magic bullet. There are a lot of good ideas for self improvement, and the important aspect is adapting them for personal gain and not taking them as is.

    Thanks, again.

  11. “Run your own experiments and see what works for you.”

    Wonderful words that I echo in many of my classes!

  12. Hi James,

    Thanks for your article!

    I have always heard how important it is to have breakfast in the morning because it starts your metabolism. I’ve always liked the notion that we should eat meats and eggs and other proteins in the morning, and have much lighter dinners.

    What is your opinion on the metabolism thing? I suppose it just depends on the person?


  13. Excellent article! Point to note : a) To drink lots of water during I.F. (b) not recommended for diabetic patients.

  14. Love this article thanks as always. Have been following IF for some time now and sometimes fell off the wagon now and then. I feel having more energy now each morning after a fasted workout. Yes having one food less to decide about everyday is a big time saver not to mention the savings lol. I think I can stick to this for this is not a fad diet just an adjustment to your typical eating pattern.

  15. Hi to you all, good people.

    I find James interview on Jimmy Moore’s live show about intermittent fasting link not working. It says it’s 403 – Forbidden.
    Am I the only one with this problem?

    I’m interesed in this topic and i will try it out.

  16. Another wonderful article. I think I’m still “looking” for the one page solution instead of just experimenting on myself. Thank you.

  17. I read your articles with great insightful. This is quite a refreshing take on the issue of Fasting which people in India do regularly.

    On the issue of self experimentation, since you like reading books, I would suggest “My Experiments with Truth” by Mahatma Gandhi. He took the concept of self-experimentation to a whole new level. You might find it interesting to read.

  18. James,

    First off, I have never tried intermediate fasting. I have to say that I am intrigued. I will have to check out your longer mega-post and give it a shot and see how it works for me.

    Experimenting — right?

    As you point out, that is the key after all. You never know what will -and will not, work for you until you give it a try. I think one of life’s truths is that there is no set “right” answer. Most things, from health, fitness, business, relationships and on have multiple “right” ways to get the results you desire. It all depends on each of our personal strengths, weaknesses, personality and our unique view and situation.

    The only way you can find what really works for you is through this sort of experimentation.

  19. Have been using the eating regimen from 1 until 9 for 3 weeks. Really like it & feel more energy and a better overall sense of well-being.

    I would like to take off 25lbs. Any diet regimens that are recommended? I am 66, take no medications, workout with weights on Tuesday and Thursday, 90 minutes of hot yoga on Monday, Wednesday and Friday. I am an avid sailor, a snow skier, and a generally active person.

    I’m a meat and potatoes kind of guy and enjoy scotch, bourbon, gin, wine , and beer.

    Any suggestions will be much appreciated. Thanks.

  20. I found your post via Lifehacker, but had read some of your posts before. Thanks for sharing your experience!

    I’ve also experimented with intermittent fasting, and played with different a five hour window, an eight hour window, and alternate day fasting. I’m female, so I’m not sure if that played into things, but those just didn’t work for me. I got too hungry, was exhausted, etc. About two months ago I started a modified alternate day fasting method based on Michael Mosley’s book, and so far it’s going great. For women, this might be a strategy that would work.

    Your mileage may vary, of course!

  21. Hi James,

    Being Indian, fasting for long periods is not alien. So many of us do some kind of fasting every week, on a designated day, month after year, without making too big a deal of it!

    Yours is a practical, sensible sort of method, and should be very easy. I can vouch for the fact that is very easy to not eat for many hours, and then eat for some. Have never really kept a chart, but I now intend to.

    Just a small Q: do you not have tea/coffee/any beverage upon waking, and eat/drink straight at 1 pm? What’s your wake up strategy then? Just plain water? What about those of us have tea and some nuts and fruits? I then go straight through till 12 pm, and then 7 pm.

    Would be nice to get a response.

  22. James,

    I too have experimented with a number of IF protocols. Most recently I experimented with the 16/8 protocol you mention here and the same exact feeding window. I included a full testosterone panel and RMR testing in my benchmarks. Both decreased rather significantly. I must note that I was periodically training both Olympic lifting, and occasionally CrossFit during my fasted period but more frequently in my fed period. There are confounding factors that I believe I have identified as causing the testosterone drop, however I can say with confidence (but not certainty) that IF caused the drop in RMR because I corrected and controlled for those factors in the final 40 days of of my experiment. I was also eating more than adequate calories and not losing weight during the test. was wondering if you tracked any additional data beyond what your recent bloodworm shows?

    I also want to comment that I agree completely on points 1, 2, 4, and 5. It is actually hard for me now to implement breakfast into my schedule!

  23. Great article. Thanks for sharing. I saw this on Lifehacker and clicked over. I started IF December 1 of last year and have shed 115 pounds so far. Another 20 and I’ll have reached a goal that has been outside my grasp for 30+ years.

    My particular form of IF was “Fast 5″ for most of the last year. Eating unrestricted but for only 5 continuous hours daily. It took a couple of weeks to adjust but then it was so simple and effortless to follow. As I’ve come closer to my goal I’ve expanded the eating window slightly and although it has slowed, the weight loss has continued at a healthy rate.

    My doctor was skeptical but supportive of my “experiment.” She now is in awe of my results and my health is better than it has been for decades. After 20+ years on high blood pressure medication, I’m no longer on any prescription medications.

    As you said, it may or may not work for any individual. But taking the time to do some self-experimentation and finding what works for you is rewarding beyond measure.

  24. Hi, It is actually a practical question about intermittent fasting:

    All my life I have heard bad things about going to sleep on a full stomach so I sort of in for not eating anything after lets say 6pm as food digested thereafter may burden your stomach during the sleeping hours. If we buy into this theory at all, would it make sense to honoring this to slightly adjust your eating window shifting it from 10am to 6pm still keeping it for 8 hours and eating all you can during this time but not eating after 6pm (or later depending on your curfew habits)?

    Thanks a mill,

  25. Like he said, research , and try it out on yourself, because everyone is different. I have been doing it for, like 5 months. I have lost like 3 pds, but, it’s because, I basically eat whatever I want within the 8 hrs. I walk everyday, but I don’t do weights enough, just once a week. So, like he said, you need healthy eating, weights, and this, if it helps you. It helps me because, I was gaining steadily every month, and now I am not. I drink coffee or tea, until 12:00. And than I eat. I eat 2 meals, and a small snack in the middle. Because, I have to quit after 8 hrs. I no longer continue to nonstop snack, and this is an easy way to eat, for me. I can control myself, because the door is closed!

  26. Great piece James!

    Intermittent Fasting is something I’ve been utilizing for years myself and it is working great. Having read many scientific journals on the topic recently, I’m even more confident now, that IF is probably one of the best sustainable dieting approaches out there. Actually, I don’t really want to call it a diet at all, but rather a lifestyle choice.

    I’ve even managed to hit the bodybuilding stage using IF, so yeah, it can be used by anyone for sure. It may not be for everyone, but I think most people should try it out at-least once.

    Personally I also tend to use the 16:8 pattern, but sometimes I change it up to as low as 12/12 or higher like 20:4. Recently I’ve also gone more towards Brad Pilon’s method, which is utilizing a roughly 24 hour fast 1-2x a week.

  27. I Totally agree.

    I’ve been doing 6 small well ballanced meals a day and it was SO hard for me, i’ve gave a chance to this and my life it’s much more simple and I see now food like the thing it is: fuel, and not something to enjoy. I can say that I was near to an eating disorder, obsessed with eat every 3 hours.

    I still count calories and keep my sources healthy and this makes it so simple.

    I recommend anyone who is in a good health shape to give it a try, we don’t have to believe everything that supplement industries want to sell us.

  28. For me IF was the way to go for many years in my life without doing it based on any protocol. I was always used to skip breakfast drinking a coffee and eating my lunch in that way I was felling more productive during the morning and energized. I still gained a lot of weight the last 2 by eating and drinking a lot around 45kgs. this year I decided to change so I started working out with heavy weights and counting my macro intake. I lost a huge amount of weight but my progress stalled around the 13% I was advised and trying to stick with the general belief of 6 meals — 5 meals but it doest working for me I was feeling very hungry and exhausted. After some thought I jumped back on IF it helped me control craving and I work out fasted in the morning and doing carb cycling I reached 10% body fat (Leangains protocol) and I feel more energetic than ever also IF helped me with bloating and other gastro problems I had! As it is said, everyone seems to be different so you have to listen to your body and do whatever feels better for you.