Mouse study provides support for the concept of intermittent fasting

The need for regular meals are a regularly-occurring feature in healthy eating and weight loss advice. I used to believe this myself. But in the last year or two I’ve had to reconsider my thinking on this on this on the basis of my own personal experience as well as people I’ve worked with clinically. Basically, I’ve come to the conclusion that prolonged periods of food avoidance can have benefits for weight loss and health, perhaps through some ability to optimise the functioning of certain hormones including insulin. I was asked earlier this year to write a piece about the concept of ‘intermittent fasting’ for The Times newspaper which you can find here.

One of the more common intermittent fasting strategies is to confine eating to a preset ‘window’ (usually 6-8 hours) during each 24-hour day. I was interested to read of a recent study, albeit in mice, that appears to lend some support for the idea that such a strategy may have benefits for health and weight control [1].

In this study, mice were fed in one of two ways. One group of mice were allowed to eat as much as they liked night and day. Another group, however, had their eating restricted to just 8 hours every 24-hour cycle. The mice ate the same type of diet, and ended up consuming the same amount of calories too. However, the impact on the two groups of mice was different in a number of ways.

For example, those mice with restricted eating ended up weighting significantly less than the other mice. Insulin functioning was improved too (improved insulin sensitivity is generally taken as a good thing and something that would help reduce the risk of weight gain and chronic diseases including type 2 diabetes over time). Functioning of the hormone leptin was improved too, which is important as this hormone is known to help speed the metabolism (and may suppress appetite too).

The mice that were restricted in their feeding has lower levels of inflammation. This is perhaps important because inflammation is believed to impair the functioning of both insulin and leptin. These mice enjoyed relative protection from liver damage too.

Mice are not men, so we cannot assume that the findings of this study apply directly to human beings. However, I do think this sort of research serves to remind us that it’s not just what we eat, but when we eat it, that might have some influence on weight and wellbeing. And even though the research is conducted in animals, it provides at least some support for the idea that contracting the window during which we eat each day might bring us benefits.


1. Hatori M, et al. Time-Restricted Feeding without Reducing Caloric Intake Prevents Metabolic Diseases in Mice Fed a High-Fat Diet. Cell Metabolism 17 May 2012

16 Responses to Mouse study provides support for the concept of intermittent fasting

  1. Craig 18 May 2012 at 5:28 pm #

    I believe IF is important because you never know what hunger is physical and what is in your mind until you’ve gone at least 16-24 hours without food.

    Monday-Friday I will have a 16-hour fast and an 8-hour feeding window. Weekends I’m a bit more liberal, but not much (always 12 hours fasting minimum).

    And you know, I always feel so much better when I stick to it. I don’t have to worry about food and I can focus on other tasks without being interupted. I would recommend it for anyone!

  2. Angela 18 May 2012 at 5:29 pm #

    To be honest, I am sceptical about this, and not merely because these are mice. When I suffered from a candida infection, I was always acutely aware that if I went without food my symptoms (such as bloating etc.) became markedly worse, indicating (to me, at least) that my body was responding to the lack of food as a major stressor. If anything, one might have expected a lack of food to lead to calmer intestines, but the very opposite was the case.

  3. Monique Palmer 18 May 2012 at 6:26 pm #

    I think there may be something int this intermittent fasting that needs to be exlpored further.
    Dr Mark Pimental , leading gastrointestinal specialist , IBS specialist mentions the guts need for regular ‘ cleansing waves to occur ‘ ( ie periods of time without food ) to help prevent bacterial overgrowth in the small intstine…. now seen to be a key contributing factor in IBS

  4. Daisy 18 May 2012 at 6:38 pm #

    I love the idea of IF, and when I first tried it, lost 3 kilos fairly quickly. Then over Christmas I piled it back on (and more), and nothing has worked since. Plus I’m RAVENOUS by the time I sit down to eat, and end up gorging. The practical aspects really appeal to me, but the physical ones don’t seem to be working. Any ideas why this might be and how I can make it work? I’m not great with willpower…

  5. Craig 18 May 2012 at 7:26 pm #

    Angela, ultimately it’s what works for the individual’s circumstance that will determine whether or not IF is right for a person. In your circumstances it wasn’t, but that doesn’t necessarily mean IF doesn’t have any benefits. Personally, I’ve seen many many benefits to IF so much so that I do it every day.

    Dr. Briffa in his article about IF stated that:

    “Intermittent fasting has merit, I think, but it’s not for everyone.”

    Although he went on to name particular groups of people who shouldn’t IF (as do many of the guides on IF from people like Dr. John Berardi, Ph.D. and Brad Pilon also emphasise), the point stands for all who might give it a try — It’s not for everyone.

  6. Craig 18 May 2012 at 7:47 pm #

    Daisy, I only lose my willpower when I am on a particularly high carb binge.

    Are you a low carb eater? If not, I imagine that IF would be UNBEARABLE.

  7. Neil Fiertel 18 May 2012 at 11:03 pm #

    If I eat an omelet and some veggies or fruit, I can easily go twelve hours without eating. If on the other hand I were to have carbohydrates of any sort…even just a small addition of it to the meal, I could never make it for twelve hours. This is telling me something..and ought to telll others also..that carbs tend to call upon insulin with a rapid onset and thus a rebound that calls upon us to restock the glucose supply RIGHT NOW..and not allow for the slow rise from slow digestion of proteins and fats. Having lost 50 lb through a high protein and low carb regimen along with lots of fruit and veggies and legumes, eggs, meats and fish, take my word for it or if not…try it yourself. If 12 hours of non eating does not work for you as it well might not, go my route. Proteins do not raise the insulin requirements the way any carbs do, no matter if they are high fibre or not…Only mechanically trapped carbs are slow to digest. The presence of fibre does not guarantee slow uptake so do not be fooled by high fibre foods unless they are unrefiined such as barley for example wherein the carbs are a part of the nature of the grain itself and not a kind of added “feature.” To be assured of a low carb food, how about just skipping them and eat a plate of chile or lentils or a yes.. a sausage and egg or a fillet of salmon poached with yoghurt and a nice portion of green and red vegetables? It is so easy to eat that way and for a snack some unsalted nuts…Want a fast lunch…a can of mackerel or sardine filleted or canned salmon and so forth….It is not rocket science…just pass by the bread, cookies, cakes and enjoy what you do eat.

  8. Craig 19 May 2012 at 12:12 am #

    Same experience as me, Neil.
    I can barely go 12 hours if I have a carb binge… But if I’m eating well (sometimes 6-8 eggs a day, fish, meat, nuts, seeds, veg, some fruit, some dairy), then I can go 24-hours, at least, no sweat!

  9. Park 19 May 2012 at 2:04 am #

    IF wasn’t easy initially because of a life long humongous breakfast habit, but after a few weeks it became very easy to adhere to. I’ve been following a 16 hour daily fast ( for several months as an experiment to see how lean I could become. I can’t speak to any metabolic improvements that may have resulted, but I have shed body fat with shocking ease. I see vascularity over my entire body yet my weight has remained constant. If anything, I’ve gained lean mass while losing fat, which is very hard to do, especially with a more regular conventional feed schedule. I sometimes feel hungry, but I’ve learned to live with the hunger pangs and not panic when they first appear. So what started as an experiment, is I think, going to be a permanent change in when I eat. IF is powerful stuff.

  10. audrey wickham 19 May 2012 at 12:35 pm #

    I don’t eat while I sleep – that’s nine hours and don’t have breakfast for about an hour on waking. Doesn’t that count as ten hours fasting?

  11. Craig 19 May 2012 at 2:55 pm #

    Audrey – Well, yes, but intermittent fasting is generally longer than 10 hours. It’s usually 16-hours of fasting per day, or one or two 24 hour fasts per week.

  12. iRememberWhen 20 May 2012 at 10:36 am #

    You absolutely don’t want me to skip a meal – honestly. I become worse than Godzilla. The anger rampage is terrifying. No way would I ever try this IF thing – it’s too dangerous for civilization.

  13. Emily 21 May 2012 at 9:33 pm #

    I lost 27 lbs following a program that heavily emphasized 5-hour fasting between each meal. So I’d eat between 8a and 9a, between 2p and 3p, and between 8a and 9pm. It was easy to wait 5 hours between meals so long as each meal included plenty of fat.

  14. Craig 22 May 2012 at 11:13 pm #

    I eat six eggs a day, with plenty of raw veg, salad, meat, nuts, dairy, seeds, yogurt, etc… And I can’t say I get that problem!

  15. Daisy 23 May 2012 at 1:10 am #

    Thanks so much for all this advice. I try to eat low carb – pasta has gone from once a week to once a month at most, semoule and rice ditto. But I live in France, and it’s a real challenge avoiding bread. I cut it out for a few days, & then am GAGGING for a chunk of baguette. I mean, what IS low, exactly? And the other question I have about eggs. I would happily eat them every day, but keep hearing (only yesterday on the BBC) that they cause constipation (to which I am already a menopausal martyr). Which is true?

  16. Daisy 23 May 2012 at 5:57 pm #

    That is great news!! I’ve always steered clear of eggs – but now I’ll go for it! Thanks, Craig! (Where did this myth come from, then?!) Plus I just had a tin of mackerel (with mustard sauce, is that OK?) and an apple for lunch – yummy, practical & satisfying – thanks, Neil. À suivre…

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