Book reviews | The Fast Diet by Dr Michael Mosley and Mimi Spencer

Book reviews

The Fast Diet by Dr Michael Mosley and Mimi Spencer

It’s a measure of how frantic we are to lose weight that Dr Michael Mosley’s diet book The Fast Diet shot straight to number 1 on Amazon yesterday. But is it worth buying?

I’ve been on the diet for just over a month and lost 4kg despite Christmas so there’s no doubt the method works. The idea is brilliantly simple - on two non-consecutive days a week you restrict yourself to 500 calories a day (600 for men), the rest you eat whatever you like. Well, not quite. If you attempted to make up for your semi-fast with a massive burger blowout you’d probably wouldn’t make much progress. But happily the fast days have the effect of taking the edge off your appetite.

The most interesting and useful aspect of the book is Mosley’s explanation of the science behind the diet which covers the research he did for the Horizon programme in the summer which kicked off the craze. Fasting, he says, is a natural state for humans and restricting your calories regularly can not only help you lose weight but help to prevent diseases such as diabetes, alzheimers and cancer.

His collaborator lifestyle and fashion journalist Mimi Spencer deals with the practical side - what to eat and when. There are menu plans - though based on two meals a day rather than the three I, and I suspect others, go in for - and calorie charts.

The book shows signs in places of being put together at some speed. No wonder. It would have been galling if someone else had stolen their thunder when Mosley had done all the pioneering work. There is in fact an e-book (and now a paperback) called the 5:2 diet which a smart journalist called Kate Harrison rushed out before Christmas.

Twenty pages are given over to testimonials from fellow dieters on bulletin boards and Twitter which, while reassuring, seems a bit lazy. And you sometimes wonder how aware Mosley and Spencer are of the calorie content of some of the foods they recommend.

The advice to add a tablespoon of oil to a salad for example would immediately knock 119 calories off your daily tally*, the few nuts recommended as 'brilliantly satiating' could easily add more.

The menus are worked out to fall within the 500 or 600 calorie limit but Spencer says she then adds a couple of snacks which would take her over if she follows them. The 5:2 diet book is better on the practicalities.

The most interesting revelation though was that Mosley normally skips lunch on non-diet days which helps to account for his own spectacular weight loss (well over a stone) and possibly explains why the rest of us plateau after a while. There could be more on how compulsive grazers (and greedy food writers . . . ) could adapt themselves to the diet which requires a strength of will that isn’t quite acknowledged in the book. Certainly having a dieting pal, as they suggest, is a good plan

Still, if you’re contemplating the diet and want to know why it works and why it’s so good for you it’s a worthwhile investment. It’s not expensive after all. But you may want to glean some more practical tips from bloggers who have been posting their recipes regularly: Fiona Maclean of London Unattached, Jacqueline Meldrum of Tinned Tomatoes and Karen Burns-Booth of Lavender and Lovage to take three examples. And there are some on my own Frugal Cook blog here.

You can also find some good recipes from food writer Xanthe Clay - another devotee - in the Telegraph.

PS a useful tip from the book: before you start the 5;2 diet should work out your BMI and take your waist measurement as well as weighing yourself. I didn’t so can’t quantify my progress fully though I have dropped a jeans size. Huzzah!

* The authors say they don't recommend a tablespoon, only a teaspoon - see comments below. Which would make more sense

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Comments: 29 (Add)

Fiona Isaacs on August 17 2021 at 16:30

Hi Fiona,

Just wondering if you are still doing the 5:2? I don’t read much about it lately and wonder if it’s gone out of favour? Would love to know your thoughts. Best wishes Fiona Isaacs

Brooke on July 29 2013 at 19:36

I am 47 years old and have never really struggled with weight... until the last couple of years, and my "problem area" is now my stomach rather than my lower half. I'm guessing age and perimenopause are partly to blame as I have not changed my eating habits and I work out 3-4 times per week. I have researched the 5:2 plan and am considering giving it a try, but have heard that if you do not have a lot to lose (I'd like to lose 10 lbs) then it is not any more effective than other diets out there. Has anyone found this to be true (or not)?

Lina on June 29 2013 at 14:40

Hi I only have about 5kg to lose and have been doing this diet for approx a month iv only lost 1.5kg which is what the scales say even though i dint see much difference however as I'm a continuous picker I'm particularly proud of myself on my fast days. As i work in a cafe I'm doing the 2-2 fast which makes it easier as im around food all day my question is whether I'm doing this correct. I have chosen Mondays and Thursday I have a filling lunch on Monday and then at dinner I have steamed veges followed by green and peppermint teas then in the morning I have water with lemon and up until 1.30-2 I have herbal teas coffee and water am I doing this correctly???

Fiona Beckett on April 18 2013 at 08:00

Look, I'm no expert on the 5:2 just someone who has used it successfully (20lbs down and counting!) so wouldn't claim to be an authoritative source of advice. The diet isn't going to work for everyone especially if you have pre-existing medical conditions.

@LB I would consult your doctor before continuing the diet

@Bonnadelle - you're right there has been adverse publicity about artificial sweeteners. The book does advise against low calorie drinks, I seem to remember though can't check as I've currently lent it to a friend

LB on April 18 2013 at 06:50

I get horrible migraines, usually triggered with lack of sufficient protein, or low blood sugar. I tried this, and was absolutely debilitated by the end of the day. Going to try it again though. Anyone have any ideas on low calorie protein rich food that might help stave off the migraines?

Bonnadelle on April 9 2013 at 15:21

I recently purchased the book and am excited to start making a change! However, I do not see information about artificial sweeteners. There has been a lot of negative press about them lately. Where, or do they, fit into this program?

Fiona Beckett on February 26 2013 at 07:22

You're right, Fridge Forager, the health aspects are just as appealing as the weight loss. I've been on the diet for 3 months now and haven't felt healthier for years! (And have lost 18 lbs!)

Fridge forager Eoin on February 26 2013 at 04:22

I have never been on a diet in my life, preferring exercise to self-control. At 41 however regular exercise isn't working anymore and I have slowly slipped to 8KG above my fighting weight. The trend is there for me to see and the problem is my calorie intake.

What I loved about the program was the scientific viewpoint regarding aging, treating weightloss almost as a side issue. I think that is a wholly righteous position as health rather than weight is the important factor in all of this. Habit are very difficult to change and getting comfortable with new ways of life take time. I have just begun the fast-diet and I hope to feel its benefits, if I loose some weight along the way to becoming healtier that would be most welcome.

Congrats on, and thanks for your work..

Gmcx on February 2 2013 at 21:33

Omg god people have said I have had an eating disorder following this regime which I have done for the past 20 years or more this life style definitely works !!!!! I have only just heard of this diet but omg feel a weight lifted from my shoulders as I use the life style to maintain my weight which is the same as when I was in my twenties ..I am probably in better shape .....thank god I am not just weird ...... I just didn't write this book which sounds fantastic and which must work because I have always lived like this is not me who is weird around food just everybody else !!! I would love to be able to contact this doctor to say thAnk you for finally making me not weird xx

Mark Hutchins on January 8 2013 at 04:02

Brad Pilons Eat Stop Eat book has been out for nearly 6 years advocating 5:2, its nothing new or revolutionary but your sure do get the results

Fiona Beckett on January 5 2013 at 21:36

Touché! Can't recall where I picked that up but if I'm mistaken, apologies. Reading too quickly, as you suggest ;-) Don't think it is entirely clear that the snacks you mention would mean you'd need to cut back a bit on the sample menus though. Maybe there can be some 3 meal or 2 meal + snack suggestions on the website when it goes live?

Congrats on being no 1 on Amazon though. Respect!

Mimi Spencer on January 5 2013 at 17:16

Thanks for the review Fiona, and glad you like the book. Well done on the weight loss front too - it really is a remarkably effective diet, as we are all discovering.
Couple of points - when I have a snack (an apple, say), I am sure to include it in my daily calorie quota, so I always stay under 500 calories - think and hope this is clear in the book. And we never say add a tablespoon of oil! We do suggest a teaspoon of oil in a dressing on a fast-day salad - a little fat in the diet can help absorb vitamins, so its no bad thing. Don't want your readers to think we're asking them to sling quantities of oil at their suppers... maybe you put your review together at some speed, haha! Thanks though, and all best wishes, Mimi

Fiona Beckett on January 5 2013 at 09:43

I try and keep off the wine - and other alcoholic drinks - as tasting it is part of my job (one reason for the weight gain over recent years!) but if I've not exceeded my calorie allowance I have a square of dark chocolate at night (55 cals). Treats/rewards are important on any diet I think.

And well done on surviving Christmas!

Kate Harrison on January 5 2013 at 09:32

Hi Fiona,
Thanks for the mention of my book - and great to read the review of Michael's, as I've ordered it from Amazon and am very much looking forward to reading it!
Just been reading your Frugal Cook blog, which is really interesting - I love the recipes on Tinned Tomatoes too.
And well done on dropping a jeans size. The most amazing thing for me has been I've put on very little weight over Christmas, despite only fasting for one day and not restricting myself at all. I also occasionally allow myself a little (very carefully measured out) wine on a fast day. Naughty but nice.
Kate x

Fiona Beckett on January 4 2013 at 18:22

I think that's key, Gillian. I find I've been buying more prepared soups and spreads just to avoid hanging round food for too long. And they're all calorie counted for you!

Gillian on January 4 2013 at 15:00

I started a 5.2 diet a few weeks before the Horizon programme went out. I was certain that the weight loss of 1 or 2 pounds per week was extremely welcome but the Horizon programme's explanation of the health benefits made it a winner for me. I'm over 2 stone lighter and I still can't really believe that I eat my normal diet for 5 days a week but still lose weight. I base my fast days on a diet of homemade soup that I make in bulk and freeze, that way I'm in and out of the kitchen as quickly as possible.

Fiona Beckett on January 4 2013 at 10:37

Thanks for taking the time and trouble to comment, Michael. Interesting point about fat soluble vitamins. And it's easier of course to justify a tablespoon of oil - or a few nuts - if you're diving your daily ration into two rather than three as I do. Maybe I should rethink that.

Like the idea of eating things you don't much like as a deterrent, too though fast days are tough enough as it is ;-)

Michael Mosley on January 3 2013 at 19:30

Hi Fiona,
Thanks for the review; you are right that oil adds calories but it also makes the whole thing taste better and allows absorbtion of fat soluable vitamins. A few nuts are not high calorie; a handful are. I find it useful to have nuts i don't really like (i can guzzle loads of peanuts but not almonds). I also appreciated the links to some great looking recipe sites. I am putting together a website with Mimi ( so perhaps we can link up. You are right, I never planned to write a book and only started a couple of months after programme went out after getting lots and lots of emails and tweets from people who had tried it and wanted advice.

Fiona Beckett on January 3 2013 at 17:15

Yes, I note down calories too as it's so easy to slip over. I wouldn't say I sleep better (never slept that well) but much more energy, certainly.

Karen on January 3 2013 at 17:08

I forgot to mention, I also make a note of my calories throughout the day and I find that a formalised menu plan at the beginning of the week helps me keep on track.

How are you finding it? Are you sleeping better and do you have more energy?

K xx

Karen on January 3 2013 at 17:06

Thanks so much for mentioning me, as well as my blog Fiona.

I stopped the 5:2 diet over Christmas, but have picked it up this week with a solo fast day this week, and a 2 day fast day schedule next week as normal.

I have lost over a stone over three months, with a few weeks of falling off the wagon, some pesky restaurant reviews (!!), but I have not gained any weight, so it works for me.

I also feel VERY energised with much more energy and I sleep better too.

I have pre-ordered the book, but, I will still be creating menu plans and recipes, as I enjoy the challenge of making my favourites "lighter" without losing the taste and flavour.

Happy New Year!


Lavender and Lovage

Fiona Beckett on January 3 2013 at 17:05

Actually, Jac, I did manage to squeeze in a couple of days including New Year's Day (not hard as I was feeling somewhat the worse for wear ;-) So managed to only put on a pound. Easier now so much temptation is removed though.

Jacqueline on January 3 2013 at 16:58

I've ordered the book too. I am finding the diet easy to do and like Fiona, at Christmas or on holiday I skip it then get right back to it afterwards. I have lost 12lbs, but dare not get on the scales for a few weeks, after the excess of Christmas. Thanks for mentioning me in your review.

Tinned Tomatoes

Fiona Beckett on January 3 2013 at 16:37

Hi Fiona. I've spotted those too. I agree it does help to record your progress - somehow it makes it more of a commitment. And your blog has some great ideas.

I know what you mean about 'fad' diet Paul but I instinctively feel this is more 'normal'. Basically you're eating what you normally do but less of it. There's always the happy thought you can eat what you want the following day.

And thanks for the calorie counter link, JJ. Very useful.

Fiona Maclean on January 3 2013 at 16:28

Thanks for the mention, I find writing up what I am cooking strangely cathartic. I've been doing 5:2 now for a few months, with a break when I went off to Sicily and another for Tuscany. It really does seem to work - I've lost weight and I feel a lot better after a fast day!

I've also ordered the Michael Mosley book...and there are a couple of good facebook groups for moral support too.

Paul Flint on January 3 2013 at 16:20

I've ordered the book to give it a go. I've lost over 120lbs in the last few years and I need a final push. I also want to something that will sustain me once I reach my goal. If this can help that and give me better diagnosis going forward I'll be happy. I'm hoping its not just another "fad" idea but after watching the TV show and hear good reports from people who use it, I don't see why it is or should be.

JJ on January 3 2013 at 16:08

For calorie counting, I use - it's heavy on the fast food (as in junk fast food - it's very American) but does seem to have everything in there.

Fiona Beckett on January 3 2013 at 10:31

I know. It's quite endearing. I think the success of the diet took everyone by surprise. There are calorie-counting sites like myfitnesspal which you have to sign up for but it's free and you don't need to adopt their programme. I personally Google ingredients individually e.g. calories olive oil which I find quicker than trawling around any one site

Joanna on January 3 2013 at 10:24

I have ordered a copy of the book as I hoped it would summarise the Horizon programme and offer some guidelines for fast days which is, from a practical point of view, what one needs. It is interesting in this day and age that Dr Mosely didn't have a book 'ready and waiting' to coincide with the original programme, I find that quite reassuring that he wasn't making the programmes to sell books. Presumably that was something suggested to him after the reaction to the programme airing? What I would love is a site that let you look up calories without wanting you to sign up for some system or other, have you come across one in your travels Fiona?

Best wishes, Joanna

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