Variation in fasting intervals

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  • Given the recommendation that there be at least 12 hours between breakfast and the evening meal on a fast day, I was wondering if the following alternative would be acceptable.

    I generally don’t have any problem missing breakfast and abstaining from any food intake until about noon. But at around 2 PM temptation really begins to hit hard.

    So I was wondering if Fast Diet benefits could still be realised by abstaining completely between midnight and midday, then taking a snack, then abstaining again until the evening meal at around 8:30 PM.

    So rather than observing the Fast Diet as described in the book for two days a week, I would be quite happy with the above approach several days a week, or even every day. I am on the Fast Diet for weight loss.

    I have regular blood tests and checkups with a specialist because I have Wegener’s Granulomatosis, currently in remission. I’m a strong 70 years of age with a large, broad muscular build, but now significantly overweight, partly due to high doses of corticosteroids and other unpleasant drugs for a long period of time while I was fighting off the disease. My bloods are always good right across the board now, and BP is always well within normal range. I am unable to do much in the way of exercise due to knee and hip injuries which are permanent impediments.

    So if I abstain completely for 12-14 hours between say midnight and 2 PM, at least several days a week, will I still reap the benefits of the Fast Diet?

    Hi Anony:

    I am not aware of the recommendation that there be at least 12 hours between breakfast and dinner on diet days, but if your goal is weight loss, the recommendation is pointless. Research shows it does not matter if you eat once, twice or three times (or more) on diet days. As long as you stay within the caloric requirements of 500/600 cal. or less, you will be fine. You will lose the same amount of weight regardless. This might help explain: This may help you with how 5:2 is done:

    There is no need to make 5:2 this complicated!

    Good Luck!

    Hmmm, I think you’ve missed something in the plan. There are specific recommendations against multiple meals in a day. What you’re suggesting is simply calorie reduction, which ignores the proposition that there is added benefit in going for fairly long periods without food at all. Eating lettuce all day is calorie reduction, and there is no doubt that weight loss will follow, but it’s not the Fast Diet.

    Here are a couple of quotes from the book which reference 12 hours, and which I was able to find fairly quickly because I knew pretty much where they were. There are probably others as relevant.

    Page 94: “On a Fast Day, he’ll (Michael) normally have breakfast with the family at around 7:30am and then aim to have dinner with them at 7:30pm, with nothing eaten in between. That way he gets two 12-hour fasts in the day, and a happy family at the end of it.”

    Page 95: “It takes, for example, about 12 hours without food before your body switches into proper fat-burning mode.”

    Page 128: “Having just one meal, as late in the day as possible, will clearly intensify the fast – allowing your body a longer period in which to enter a fasted state. Others prefer to eat breakfast and then avoid food for a ‘fasting window’ of around 12 hours until supper. Since it is the fasted state that is so beneficial to us, eating lots of small meals is likely to reduce the benefits, particularly if you graze on carbohydrates.

    My take from the book in general is that a period of at least 12 hours without any food whatsoever is an important consideration in following the diet properly.


    I think Michael was telling us how he went about 5:2 rather than saying there must be 12 hours between meals, and underlining the science behind fasting. If you don’t have 12 hours between meals you will still lose weight due to calorie restriction.

    There are many following this WOE me included, who only eat dinner on FDs and don’t eat before lunchtime on any other day. I prefer to have a decent sized meal at dinner time than eat tiny amounts on a FD, and I don’t usually eat breakfast anyway.
    A long period of fasting is where the health benefits of fasting come in giving the insulin level in our bodies time to drop which helps to reverse/prevent insulin resistance, and allow our bodies to do some maintenance.

    If you find it easier not to eat until early afternoon on a FD, that is great as in my experience and many would agree, that it is easier not to eat at all because once we start we want more.

    Good luck.

    Hi Anony,

    Longer periods of food abstinence are also promoted by Dr Fung (The Obesity Code, intensive dietary management). If you’re aiming solely for short-term weight loss, the eating window isn’t so important, but longer-term benefits of fasting and weight maintenance require longer fasted periods.

    Personally I’m not sure how much benefit there is in a 12 hour fast, longer is better! I think MM just hit on breakfast and evening meal because it suited him, it’s not the Holy Grail of 5:2. I have a 16 hour ‘fast’ most days (I skip breakfast), and on fast days I now aim for 24 hours. A lot of people do longer, 36 hours to 3 or 4 days. What you have to remember is that 5:2 is primarily a weight loss tool, a gentle introduction to intermittent fasting for people who are used to continual overeating!

    My advice would be to forego your midnight snack! You don’t need it. Why not stop eating earlier in the evening?

    Doh, you beat me to it Amazon!

    Ha ha, I second what she says 😀

    Hi Anony,

    If you want to realise the benefits of fasting as well as incorporating the 5:2 concept then you really need to fast for about 36 hours as a minimum. I monitor my blood glucose and ketone bodies. You can buy cheap BG/Ket meters from ebay and the like. I am just entering ketosis after 36 hour (one complete day, so last meal is dinner on Sunday, and then breakfast on Tuesday) and am well and truly into ketosis by 60 hours (Two complete days. So Sunday dinner and then Wednesday breakfast).

    12 hours is not going to get you into ketosis, its just a ways to restrict your calorie intake.

    Thank you all for your input. For those of you who regularly undertake multi-day fasts, I really admire your willpower and tenacity!

    Part of my problem is an attitude of “been there-done that-really don’t want to go again”.

    See, when I first contracted Wegner’s back in 2008 it was well advanced before it was diagnosed and so the treatment was long and extreme. Very high doses of corticosteroids and other poisonous crap for a very long time. Partly due to the drugs and sympathy-eating my weight climbed to 200 kg. When the specialists finally got me into remission I went straight onto a weight loss campaign, based on a diet designed by a Brisbane doctor. In about a year I lost 90 kg. With my build I’m comfortable and look good at about 110 kg.

    Then a bit over a year ago the Wegener’s resurfaced, back on the drugs, up goes the weight again. I’ve only recently been declared in remission again, so once again it’s time to try and shed the weight. I made several attempts to get back on the previous diet that had been so successful, but I kept falling off the wagon. The first time was such a monstrous effort that I guess I just didn’t have the heart to do the same thing all over again.

    When I’m well (Wegener’s in remission) I’ve never had a problem going without food until early to mid afternoon, so when a friend told me about the Fast Diet I thought maybe I might have more success with a change of pace, which led me to here.

    The first week I had three fast days, eating just the one 600 cal meal in the evening, and although frequently tempted I didn’t feel it was all that difficult. But second week I twice succumbed to temptation and broke the fast about mid-afternoon in each case. If I’m reading you people right, that’s not so bad after all, providing I continue to keep an eye on the calorific intake.

    I guess I’m just going to have to ease into this no-eating thing bit-by-bit until my head gets comfortable with it. Fortunately I’m not worried about bloods, so if I’m reading your advice correctly I just need to concentrate on calorie reduction and forget about aiming for a certain number of hours without food. Realising of course that by extending the number of hours without food I’m facilitating the calorie reduction.

    That put me more on the right track?


    Now you are on the right track.

    Good Luck!

    Hi Anony,

    Can you tell us how has the diet been for you? Any progress? problems you’ve faced?

    I have someone I know and she also has GPA (Wegener’s Granulomatosis), currently on prednisolone and Methotrexate. She read about the 5:2 diet and is willing to start if someone else with the same condition has been through it with no problems.

    I’m looking forward to hearing back from you.

    All the best!

    I read somewhere about the benefits of a 12 hour or longer fast but it wasn’t about losing weight. It was about autophgy (not sure I spelt that right!). Good cell renewal begins at 12 hours and gets better the longer you fast. It wasn’t in 5:2 that I read that but rather in the NIH Department of Aging (USA) longevity research.

    so am i right in assuming, if we want to lose weight then as long as we stick to the 500/600Cal we are OK but if we want all the other health benefits from the 5;2 then we should fast for at least 12 hours between meals, correct?

    What surprises me with that is whats in the book. MM fast for 12 hours i.e not more and Mimi Spencer have breakfast, an apple for lunch and a dinner and they are the pioneers of the fast diet so how come?

    I hope someone can explain

    Hilali1, I think there’s two different issues here: fasting to lose weight on 5:2 and fasting for health reasons/improvements. From what I’ve been reading it takes longer term fasting, like at least a couple days, either with a water fast or commercial FMD food supplied fast, to really see a lot of health benefits. If you stick to 500/600 calories on fast days with the 5:2 diet it may not be long enough at a stretch to have major health benefits. Realistically, if you’re eating 500/600 calories in a 24 hour period, it’s pretty hard to spread that small amount of calories over the period without having at least a 12 hour or more fasting window, considering the time you spend sleeping that takes you into the following day. That said, simply losing weight carries a lot of health benefits on its own. Losing 13 kg lowered my blood pressure, cholesterol, helped with some allergies and alleviated knee pain which I thought was from growing older.

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