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Trying Out the Fast Diet


I usually try to steer clear of fad diets, so when my friend Marti sent me a New York Times article about a best-selling British book called The Fast Diet, I set it aside. But when the mysterious new diet kept cropping up in conversations over the next several weeks, I had to check it out.

The why.

Although it seems I’m always trying to shed a few extra pounds, the diet appealed to me for its other suggested benefits as well – lowering bad cholesterol, reducing cancer risk and, of special interest to me due to family medical history, stimulating brain activity. (I found more helpful info on the brain benefits of intermittent fasting in this article published in Johns Hopkins Magazine: “Don’t Feed Your Head.”)

Intrigued, I sent the NYT article to my husband and he agreed to start the diet with me on April 1. (That way if we chickened out — April Fools’!) Now three weeks into it, we’ve been getting lots of questions so I decided to document the experience here. I’m not in any way suggesting this is a must-do for everyone, and I’m still not entirely sure it’s not a fad, but I’ve been pleasantly surprised with the diet thus far and it seems easy enough that it could actually transition into a lifestyle change.

The what.

In a nutshell, the Fast Diet, or 5:2 Diet, is five days of eating and drinking whatever you want and two non-consecutive days of “fasting” — eating about 500 total calories for women and 600 for men. According to the book, even after just a few hours of fasting the body starts to burn fat instead of storing it.

The book is based on a documentary created by Michael Mosely (one of the book’s authors). If you’re considering the diet, the 56-minute video is worth a watch – it helps explain the thinking behind why intermittent fasting might work: Watch Eat, Fast and Live Longer with Michael Mosley on PBS.

The how.

Choose your fast days. Since we already fast for two meals one Sunday a month, we picked Sundays and Thursdays (with the option to switch to Wednesdays if an event conflicts).

Make a meal plan. I’m finding I have the most success on fast days if I don’t really have to think much about food. I plan in advance (usually the day before) and try to make every calorie count – scrambled eggs with peppers, tuna and white bean salad, Asian salmon, egg white salad – and try to do most of the prep in the morning. Vegetables give a lot of bang for the caloric buck, so I make sure to include plenty of them. I found a few meal suggestions and recipes on the Fast Diet website and at, and even more from my 1990s Cooking Light cookbook. I’ll include some of our favorites in future posts.

Count your calories. It’s remarkably easy for me to forget or discount what I eat, so I’ve found it really helps to stay on top of it throughout the day. There are a number of free food and exercise-tracking options out there; we like It has a huge database of foods, is intuitive and fast to use (iPhone APP too) and it even syncs with our FitBits to track our exercise for the day.

Results may vary. By way of full disclosure … although there don’t seem to be many “rules” for what you can’t eat on the non-fast days of the 5:2 diet, we are already pretty healthy eaters — lots of veggies, brown rice, lean proteins, etc. My husband has been off refined sugar for well over a year now, so we don’t keep any sugary treats in the house (though I confess I still indulge on the sly). In other words, we’re both trying to exercise more and generally watch what we eat even when we’re not fasting, so our results may be better/faster than if we weren’t doing those things.

The progress.

We just finished our third week on the fast diet, and so far, so good — my husband is down six pounds, I’m down four. The first fast day I went to bed really hungry and my growling stomach woke me up at 3 a.m., so I learned to eat later on my subsequent fast days and haven’t had a problem since.

We both feel lighter and more energetic, especially following a fast day. Plus, since it’s only for one day, the fast feels very doable. One surprise? Since there are really no restrictions on what you can eat, I was expecting to gorge on the non-fast days, but I’m actually finding that it now takes even less food to fill me up. Bonus!

13 Comments leave one →
  1. Jere Miller permalink
    04/23 5:25 PM

    It does get easier after the first week, although I still find it difficult to keep within 500 calories. I’ll try your meal ideas. Sounds more filling than what I have been eating.
    I’ve been better about not snacking during the feed days. Thanks for the motivation!

    • 04/23 5:39 PM

      As I recall, you were the original motivation for me — glad to hear it’s still working for you, too! The tuna and white bean salad is our favorite; posting recipe soon.

  2. 04/23 6:46 PM

    Excellent job! All my questions answered. I won’t have time to watch the video until this weekend, but I definitely want to give it a look and maybe… join the fun. :)

  3. wildlycraving permalink
    04/23 6:47 PM

    All my questions answered — thanks for the extra resource links. I’ll definitely watch the video later in the week. :)

  4. Dawn Rusick permalink
    04/24 11:44 AM

    I’m going to start…I really need your HELP!! :)

    • 04/24 11:46 AM

      Of course, Dawn — we can help each other. (I can even bring you samples.) :-)

  5. 04/24 4:40 PM

    My wife and I actually caught the show a few weeks back and started thinking about it. I don’t really need to lose weight, but if it helps me to get more healthy all around, then so be it. My wife would like to have it help her cholesterol levels, so that’s a good thing, too.
    Do you know if the fast days you are supposed to eat healthy things or can I use up 140 of my daily calories with a can of Coke? Not healthy, I know, but it tastes better than coffee to me!n

    • 04/24 5:35 PM

      Great to hear from you, Jason! I’m thinking yes on the healthy things — sorry. Mark Mattson, the neuroscience guy from Johns Hopkins “advises people to drink plenty of water or unsweetened tea and to eat no more than 500 calories per fasting day via fiber-rich vegetables.” Let me know if you try it.

  6. Jill Lutz permalink
    04/30 1:12 PM

    Jen – I had forgotten that you had this blog. I stumbled onto it by accident as I searched for a lowfat tomato basil soup recipe. That was almost an hour ago and I haven’t left it since. Everything you have here is wonderful but I was intrigued by this fast diet. I’m going to try it. Because of the needs of both my life and calling I already fast an average of twice a week. However, when I break my fast it is with A LOT more than 500 calories. I love how you state that they have found one of the benefits of doing this is increased brain activity. All of us know the spiritual benefits of frequent fasting with purpose. I am anxious to reap the physical benefits as well. Thank you for sharing all your glorious knowledge! Now to make that yummy tomato basil soup…

    • 04/30 1:53 PM

      Thanks for taking the time to comment, Jill, and for poking around the blog. We can compare notes on the fast diet — still finding it doable after a month. Let me know how you like the soup! xo

  7. 06/09 4:19 PM

    Ok, I’m ordering this book! I have been using MyFitnessPal, which I think is great. But I love the 5:2 concept. Thank you for sharing!

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