Academic ResearchOther Diets & Books

The 2 day diet

The Michael Mosley August 2012 Horizon programme started a significant interest in intermittent fasting. As my special report (free) explains here, the programme looked at a number of different restricted eating options (eating less all the time, fasting for 4 days, alternate day fasting). The option that Mosley found the most tolerable was eating ‘normally’ for 5 days and eating one quarter of ‘normal’ calorie intake for 2 days. Thus the 5:2 concept was launched on the British population and a number of copy cat books appeared even before Mosley’s own 5:2 book was published, as “The Fast Diet” in January 2013.

Another 5:2 diet was being researched before the Horizon programme. Michelle Harvie was the lead author on a paper published in the International Journal of Obesity in May 2011. The full article is available here .

This blog was posted on 22nd April 2013. I received an email from Michelle Harvie on 24th April requesting some amends. We have had a few email exchanges since and any changes to the original blog are in red below.

The Intermittent Fasting Study

The study involved 107 women who were randomly assigned to either a Continuous Energy Restriction (CER) diet or an Intermittent Energy Restriction (IER) diet. To quote from the article: “The CER group were prescribed a daily 25% restriction based on a Mediterranean type diet (30% fat, 15% monounsaturated, 7% saturated fat, 7% polyunsaturated fatty acids, 45% low glycaemic load carbohydrate, and 25% protein). The IER group were asked to undertake a Very Low Calorie Diet (VLCD) (75% restriction) on 2 consecutive days and to consume estimated requirements for weight maintenance for the remaining 5 days according to the nutrient composition above.”

The Very Low Calorie Diet (VLCD) part of the intermittent group’s diet provided approximately 500 calories per day. It was low carb as well as low calorie – delivered in the form of 2 pints of semi-skimmed milk, approximately 300g of vegetables, 1 portion of fruit, a salty low calorie drink (why?!) and a multivitamin and mineral supplement.

Participants in both groups were advised to maintain their current activity levels throughout the trial, and did not receive specific exercise counselling. Energy prescriptions were reviewed throughout the trial to account for changes in weight and exercise levels to maintain a 25% restriction below estimated requirements for weight maintenance.

If we assume that an average woman in each group needed 2,000 calories a day and assume for simplicity that this did not change during the trial, then the average woman in the CER group would need 14,000 calories per week and would receive 10,500 – a sustained reduction of 25% per day. The average woman in the IER group would need 14,000 calories per week and would receive 11,000 – a reduction of 1,500 calories on 2 days. Thus the weekly calorie intake and deficit would be essentially the same. (Notwithstanding everything I write about the type of calories being far more important than the number).


107 women started the 6 month study. 18 women withdrew from the study before completing the 6 months: 11 from the intermittent group and 7 from the continual restriction group. Did the starve-for-2-days group find the diet more unbearable therefore?

Here is the passage reporting the results verbatim from the study:

“Weight loss was comparable between the groups. LOCF [Last Observation Carried Forward] analysis at 6 months showed weight reduced from mean (95% CI) 81.5 (77.5 to 85.4) kg to 75 (71.2 to 78.8) kg in the IER group compared to a reduction from 84.4 (79.7 to 89.1) kg to 78.7 (74.2 to 83.2) kg in the CER group. The percentage of women in the IER and CER groups losing 5–10% body weight were 30 and 33% respectively, and losing 10% or more body weight were 34 and 22% respectively (χ2=1.89, P=0.39). Both groups experienced comparable reductions in body fat, FFM [Fat Free Mass], hip, bust and thigh circumference and composition of weight loss. Percentage of weight lost which was fat in the IER and CER groups was 79 (±24) and 79 (±26) % respectively (P=0.99).”

Removing the statistical details for ease of observation, the above passage tells us:

–        “Weight loss was comparable between the groups.”

–        “Both groups experienced comparable reductions in body fat…”

–        At 6 months, the IER (intermittent) group had reduced on average from 81.5kg to 75kg. The CER (continuous) group had reduced on average from 84.4 to 78.7kg. Both groups lost approximately 6kg on average, equating to approximately a 7-8% reduction from starting weight.

–        That’s 1 kg a month. That’s 2lb a month. Hardly justifying the Daily Mail headlines “The diet revolution that’s swept Britain.” If I starved for 2 days a week and never ate more than normal on the other 5 days, or cut back 25% every single day for 6 months, I would want significantly more than a 0.5lb a week weight loss. The record weight loss for The Harcombe Diet (Phase 1) is 17lb in 5 days. I would be astonished if someone didn’t lose more in 5 days of Phase 1 than in 2-3 months of the average on this diet and with far fewer rules and restrictions.

As Dr. Margaret McCartney noted in this clip from Radio 4’s Inside Health (listen from approximately 20 minutes into the programme) – the clinical trial “didn’t show any difference.” Quite so.

Despite the poor results in this clinical trial, the diet has been published in a book called “The 2 day diet”. (This last sentence was wrong – as you will see below – this 2011 article was not the diet in Harvie’s book). It was serialised in the Daily Mail from the 11th February 2013 onwards for a week. These articles are not available on line (to make you buy the paper and/or the book). Another serialisation started in the Daily Mail on Saturday 20th April – again – the details of the diet are not available on line.

Harvie states “The most important point is that our 2 day diet book is not based on the original milk and fruit and vegetables (650 kcal) diet which was reported in the Int J obesity in 2011. This was a proof of principle study showing that 2 day diets could work.”

This was most enlightening, as it discounts the 2011 study as being able to play any part in the “clinically proved” claim of the 2 day diet in the book. I’ve left the study in this blog, for interest, (not least to show how poor the weight loss is), but it plays no part in claimed clinical proof.

Harvie goes on to say “The book is based  on our improved low carb 2 day diet, and the  statistics used to support the weight loss reported in the book have come from our recent publication in the British Journal of Nutrition.” (BJN henceforth)

I have had an email exchange with Harvie challenging the claim that the diet in the BJN is the 2 day diet in her book. She stands by the claim and states “The diet in the book is the  diet inn (sic) the aper (sic). The diet showed significant reductions in fat which is what we claim for the book.”

However, I cannot see the evidence for this (I have a copy of the full paper). The paper compares three diets – two involving what is called “Intermittent Energy and Carbohydrate Restriction” (IECR) (my emphasis) and one involving “Daily Energy Restriction”. The paper states “The IECR and DER interventions involved an overall 25% energy restriction… Participants randomised to IECR were asked to restrict energy and carbohydrate on two consecutive days each week (70% energy restriction and 40g carbohydrate) and to consume a euenergetic Mediterranean-type diet that met estimated energy requirements for the remaining 5d of the week. Restricted IECR days provided between 2500 and 2717kJ…”

2500-2717kJ is 597-649 calories. The intermittent diet reviewed in the BJN study was both calorie and carbohydrate restricted. Taking just the protein and fat servings for a woman in the restricted days of the 2 day diet (the diet is detailed below), and looking just at calories, a woman could have 12 medium eggs and 35 grams of olive oil (choosing just two foods to keep the analysis simple – the different foods allowed are unlikely to be significantly different in calories per serving size) and these alone (before the dairy, fruit, veg, mints) would add up to 1,065 calories. Indeed in another part of her correspondence Harvie says “The restricted days often end up self limiting to around 1000 kcal i.e. a 50% and not starving yourself.”

You can’t have it both ways. The diet in the book is not the diet in the paper. The diet in the book has not, therefore, been clinically proven.

Notwithstanding this, the BJN paper did not claim any significant difference in weight loss between the diets. “Both IECR groups experienced significantly greater and comparable reductions in body fat than the DER group, but no significantly greater reductions in weight.” Harvie makes no claims for weight advantage in her email to me when she states “The diet showed  significant reductions in fat which is what we claim for the book.” However the back cover of the book states “Lose more weight and twice as much fat as on a standard calorie-controlled diet – then keep it off forever”. The last part is also unproven – a month’s maintenance followed the three month diet and a check at four months following baseline is the latest assessment recorded by the study. Significantly this is two months before the well-documented six month regain observed with calorie deficit diets.

Before you get excited about the fat claim – the intermittent dieters (having approximately 600 calories a day for 2 days a week remember) lost an average of 3.7kg of fat in 3 months. That’s just over a couple of pounds a month. A month – not a week.

We should also make the point that neither the 2011 nor the 2013 paper study men. Both study women. Hence there can be no claim that either intermittent diet reviewed by Harvie/Howell has been clinically proven for men, notwithstanding that the diets for women in the journal articles were different in both cases and neither the same as the one in the book.

The authors

The book authors are Michelle Harvie – a dietician and Tony Howell – Professor of Oncology. Together they run Manchester University’s Genesis Breast Cancer Prevention Centre.

The Claims

The front cover of the book has the words “clinically proven.” The Daily Mail February serialisation majored on the claim “clinically proven to reduce weight.” The “clinically proven” refers to the article in the International Journal of Obesity.  Despite the fact that weight loss overall was low and there was no difference between the intermittent diet and the continuous calorie deficit diet, because this was done as a study the authors are able to make the “clinically proven” claim. (As per the probably unintentionally helpful intervention from Harvie above – I can see no evidence that any clinically proven claim can be made.)

“Clinically proven to lose you an average of a couple of pounds a month over 6 months” would be more accurate. “Clinically proven to do no better than normal dieting” would have been another option.

Stopping at 6 months is also interesting as all evidence from Keys (1945) to Franz (2007) to Weight Watchers (2010) shows regain starting at approximately 6 months after starting a calorie deficit diet. The 5:2 diet has not been clinically proven to achieve sustained weight loss.

Breast Cancer

The Daily Mail got into misleading territory in the February serialisation. Here is a direct quotation from the article on 11th February 2013: “In a study of 34,000 women, Dr Harvie and Professor Howell were the first to discover that being overweight significantly increases your risk of breast cancer and that losing just 5 per cent of your body weight and keeping it off is enough to reduce your risk of breast cancer by a staggering 40 per cent.”

First, were Harvie and Howell really the first to discover that being overweight significantly increases the risk of breast cancer? Really? Here’s a study I found in a quick search dating back to 1993. Did Harvie and Howell produce a study before this?

Harvie says “For the record we weren’t the first group to report that being overweight significantly increases your risk of breast cancer, but were the first to  report  that losing just 5 per cent of your body weight and keeping it off is enough to reduce your risk of breast cancer by 25- 40 per cent within the Iowa Women’s Health Study”. 

It is not an absolute truth that losing 5% of your body weight and keeping it off can reduce your risk of breast cancer by 25-40%. A study may have found an association, not causation, of a relative, not absolute, risk. If this is the study being referred to, there were 1,987 incidents in over 440,000 person years of follow up. That’s a 0.45% chance of an incident in any study year. That’s why I get annoyed when researchers dramatise/scare people with relative risk headlines. The absolute risk is difficult to even conceive.

Secondly, if the observation is that a 5% sustained weight loss reduces the risk (remember, this will be relative risk, not absolute) of breast cancer, then any diet that achieves weight loss could claim to reduce the risk of breast cancer. Here’s my suggested headline: “The Atkins diet reduces the risk of breast cancer.”

The Mail (Feb) continued “Their diet, which is clinically proven to be more effective than conventional dieting.” This is simply not true. The 2011 journal article stated quite clearly ” Weight loss was comparable between the groups.”

The Diet

The Mosley 5:2 diet advises that the days should not be consecutive. The Harvie/Howell diet says that the 2 days should be consecutive. The Harvie/Howell diet claims that there is no calorie target on the 2 days – just foods that you can’t eat. You’re joking of course! There is a directive for fat to be eaten, carbs to be eaten and protein to be eaten – with portion sizes spelled out and these portion tables by macro nutrient are dictated for the ‘non-diet’ days as well as the ‘diet-days.’

The concept sounds simple enough” Spend two consecutive days each week enjoying protein (fish, meat, eggs) and vegetables but no carbs (potatoes, bread, pasta) and then stick to a ‘healthy Mediterranean-style diet’ for the other five days.”

This is the reality:

These are the numbers and sizes of the protein, fat and carb portions that you are allowed on DIET DAYS:

PROTEIN: a maximum of 12 servings for women and 14 servings for men.

1 portion = 30g/1oz oily fish; skinless chicken; lean beef, pork, lamb or offal.

1 rasher lean bacon; 1 egg

50g of tofu.

60g white fish.

45g/1.5oz of seafood/tuna in brine.

FAT: maximum of 5 servings for women and 6 servings for men.

1 portion = 8g margarine (avoid buttery types), 7g olive oil, 3 walnut halves or 8 peanuts, 8g peanut butter; 10 olives; 15g low-fat mayo.

DAIRY: Men & women 3 servings.

1 portion = 1/3 pint skimmed/semi-skimmed milk/soya milk; 3 tablespoons diet yoghurt; 2 tablespoons normal yoghurt; 30g/1oz reduced fat cheese.

FRUIT – Men & women 1 serving.

1 portion = 80g/2.5oz portion of low carb fruit (apricots, berries, rhubarb etc)

VEG/SALAD: 5 servings.

1 portion = 80g/2.5oz of low carb veg (green beans, asparagus, broccoli, cabbage etc).

TREATS – sugar free gum?! up to 10 sugar free mints!

DRINKS – At least 2 litres a day of water, tea, coffee or other sugar-free or low-calorie drinks.

This confirms that a dietician and a professor don’t know one macronutrient from another. Protein is in everything except sucrose (table sugar) and oils. All the foods listed under protein are combinations of fat and protein (fish, meat, eggs). Some of the ‘proteins’ contain carbs as well as protein and fat (lentils, beans).

Harvie asked me to correct for the fact that “we do not allow lentils, beans and baked beans on restricted days.” I am happy to correct this and have deleted those entries under the restricted days above.

Harvie states that she and Professor Howell “do know one macronutrient from another” and that the protein, fat and carb food lists represent the main ingredient of those foods.

Harvie and Howell may well know one macronutrient from another, but they don’t know the main macronutrient in lentils, beans and baked beans. 100g of boiled lentils has 0g fat, 9g protein and 20g carbohydrate. The remainder is water/ash. 100g of boiled beans has 0g fat, 9g protein and 23g carbohydrate. The remainer is water/ash. 100g of cooked baked beans has 0g fat, 5g protein and 20g carbohydrate. Carbohydrate is the main macronutrient in all three of these examples given.

Under fats, margarine and olive oil are fats. Nuts and avocado contain carbs, fat and protein in good measure. And what on earth are a dietician and a doctor doing advising hydrogenated (or interesterified), bleached, deodorised, emulsified, coloured and fortified margarine in preference to natural, nutritious butter? And what on earth are a dietician and a doctor doing advising low calorie, sweetened, drinks as part of a healthy diet. Have they not googled “the dangers of aspartame”?

(I was being a bit tongue in cheek here, as 99% of doctors and dieticians sadly promote interesterified, bleached, deodorised, emulsified, coloured and fortified margarine over natural, nutritious butter and don’t seem to know the harm that aspartame can inflict – Harvie and Howell are just no different). Harvie has asked me to point out “We have summarised the most up to date evidence based research on asparatame and saturated fat in the book, and not all the hype and anecdotes and personal viewpoints which may appear on Google.” The book has two paragraphs on sweeteners, covering aspartame among others. Of the many dangers associated with aspartame it lists one – blood cancer – and thus recommends limiting intake of diet drinks to no more than nine cans per week!  

On saturated fat, there is no evidence that Harvie and Howell know that meat has more unsaturated than saturated fat. They make the common recommendation to cut down on meat to reduce saturated fat and to replace saturated fats with ‘healthy’ fats, especially monounsaturated fats. There is more unsaturated fat than saturated fat in meat (red, white, whatever) and the main single fat in meat is (with the odd rare exception) monounsaturated. The book also claims that “saturated fats clog arteries.” Ha ha – only if you intravenously inject them!

NON-DIET days (Puh-lease!)

“You are basically eating a healthy Mediterranean diet with lots of fresh fish, meat, salad, vegetables and whole grains” say the authors. Please see this blog for the never ending nonsense about the Mediterranean Diet.

These are your food allowances on non-diet days. How the heck is this not a diet?!

Men (max servings)


Carb servings



11 stone




12 stone




13 stone




14 stone




15 stone +





Women (max servings)


Carb servings



9 stone




10 stone




11 stone




12 stone




13 stone




14 stone +





Serving sizes of protein and fat are as for the diet days.

The carb servings for the non-diet (ha ha) days are as follows. You are advised to “always choose wholegrain.”

1 portion = 3 tbsp whole wheat cereal; 1 weetabix; 1 heaped tbsp oats; 1 slice wholemeal bread; 1/2 roll; 2 rye crispbreads; 1 oatcake; 2 heaped tbsp cooked pasta; 1 lasagne sheet; 1 small potato; 2 tbsp sweet corn kernels.

The small print

“Do not do this diet as a child, teenager, pregnant, breastfeeding, suffering from an eating disorder. The high protein may post problems for those with kidney disease or at risk from kidney disease. Diabetics – seek advice.”

The final word

The Friday 15th April Daily Mail article described the diet as “It’s gloriously simple”!


I love maths, but I would lose the will to live even trying to work out one so-called non diet day of the triple simultaneous equation that would be my carb/fat/protein number and size of portions – even allowing for the fact that the diet doesn’t know fats from proteins or carbs.

This is a 7 day diet, delivering barely a quarter of the calorie intake needed on 2 days of the week. That’s 30% of your life starving and 100% of your life on a diet – counting portions and measuring out 80g of vegetables. (As noted above, Harvie states that “The restricted days often end up self limiting to around 1000 kcal i.e. a 50% and not starving yourself” – proof that this is not the approximately 600 calories intermittently in the BJN article).

Don’t do it!

This is obsessive and miserable and it’s proven to lose an average of 0.5lb a week – if you stick to the diet for 6 months. Then we don’t know if you will regain. I can confidently forecast that you will need to stay on this kind of restrained eating for life or you will regain – you will have trained your body to maintain on a lower calorie intake.

Or you could just eat real food (meat, fish, eggs, dairy, vegetables, fruits in season and whole grains in moderation); three times a day and get on with your life. But then that would be The Harcombe Diet!


22 thoughts on “The 2 day diet

  • Thank God you’re not an American nutritionist here in the U.S.

    I can guarantee you, you would be bashed by the several professional fasting researchers we have who have done studies showing weight loss AND LOWER INSULIN LEVELS by using Harvie’s 5:2 approach. Ever hear of Mark Mattson? He was coauthor of the Harvie study, and is a very well-respected researcher doing current trial tests on Harvie’s version of 5:2 and Alzheimers disease.

    How ironic that you bash all other eating methods, of course promoting your own wonder diet. Please. Stay where you. But Michael Mosley? Please sir, get your butt over here any day.

  • Pingback: The Two Day Diet|2 Days of Detox, 5 Days of Pleasure

  • I find it laughable that you choose to ignore the scientific facts as presented by the world leaders in this field. Are you trying to discredit the research carried out by picking holes out of the text? If so please make sure there are holes to pick. This article seems to me to be to promote the Harcombe diet (which is completely unproven, unlike this diet) by discrediting others. Shameful.

  • I am 5ft 4ins and weigh 9st 9lb so not particularly overweight but just have too much round the stomach. I am not sure dieting is the answer but what is. I do walk regularly and do ‘pulses’ morning and night but would Pilates or some other exercise regime be the answer?

  • I have been reading Zoe’s blogs etc all afternoon today! I find her extremely interesting ,truthful and blunt.
    I also agree with everything she says about the diet industry ,dieting DOES make us fat! I have done many of the fad diets out there,I am not obese and some would say that I don’t even need to lose any weight (They haven’t seen me naked!)
    I am 5ft 4 and at the moment I weigh 9st 9lb . 6 weeks ago I was 10st12lb. I have lost my weight by eating Real Food!!
    Lean beef,chicken,oily fish,fresh vegetables ,salads and low fat dairy products and I also enjoy a great British fry up and the odd glass of red wine !
    I have not eaten one biscuit,craved any chocolate or cakes and totally enjoy my meals! And after reading Zoe’s blogs I am now throwing out my low fat spread and buying butter!
    Like the lady Catherine Reynolds I have just become a member of a very popular slimming group,it’s working for me and the principles are very much like Zoe’s ( although you can have the dreaded carbs if you so must) I choose not to have the sinned foods and have lots of lovely berries instead.
    I am going to purchase Zoe’s book as I really believe in all that she says…. My parents and theirs were NEVER overweight! We had dripping lard for cooking and most meals were based round meat and two veg!
    We never had pizza or any processed foods and no money to buy sweets and chocolate! I was a healthy child and teenager and weighed 8st 3lb when I got married, that’s when the weight started to creep on! …. Some called it contentment! Really it was not being able to cook so I bought processed meals!
    Anyway,my life has changed and also my shape! I love the new Me and my new way of eating…… Thanks Zoe for all your great advice and knowledge,I’ve had a really lazy afternoon but a very informative one!…. Keep up the good work xx

  • I’m glad I found this page. I didn’t buy the book because it seems that was the aim of the two originators. There are anomalies in it – mainly touted by the Daily Wail who seem to be saying you can eat your cake too. I find the logic of the Mosely idea sound. Humans have had, and still do in the ‘under-developed world, an uncertain diet. Until they began to grow food and to keep livestock, humans had restricted and unpredictable intake – mostly based on plants and occasional protein from animals. In July I saw the programme on juice dieting – bought a juicer on the basis of significant weight loss of the participants featured in it BUT I then thought, “where’s the fibre in this diet” and sure enough a proportion of people who’d taken it up complained of constipation. I then recalled the Daily Mail article and retrieved it. I’ve followed it but it is complex if you allow it to be. I’ve lost weight gradually – 8lbs in 26 days and lost girth (about two inches). However I also, and this follows any sensible diet, have stopped eating bread (except full-corn rye), crisps, biscuits, alcohol, chocolate and orange juice and have also cut down on fruit. I eat vegetables and protein rich foods and drink one cocktail of vegetable juices per day – I figure that I’m getting nutrients from the juice which I didn’t get before because I regularly threw away veg. that I didn’t use it before it began to spoil. The fact that I’m losing weight is possibly down to having stopped eating processed carbohydrates and that heavily fructose laden juice or to reducing my intake (between 700-800 cals on ‘diet’ days). I’m pleased with losing weight steadily. Rapid loss seems to be the aim for some comment makers. I’m not sure that’s a good idea – losing muscle mass is a risk. I’m also exercising most days so the natural depletion of fat reserves as fuel could be taking place because I’m not intaking processed carbs, esp sugars. I may amend to Mosely but the comment by Harvie/Howell that the fat-burning kicks in after 36 hours is persuasive. That might happen were we periodically unsuccessful hunter-gatherers. Some people on here seem to, as I stated before, want their cake and eat it too. Humans evolved to expend energy in the hunt for food or in the growing of it. Ask the guinea-pigs who made the Victorian Farm’ and similar programmes.

  • I have recently joined a well-known slimming organisation with my husband (not Weight Watchers or Rosemary Conley). I did this because I promised him I would go along with his choice (he needs to lose a fair bit, and I was prepared to do virtually anything to help him). I followed the Harcombe Diet for several months, with success in weight loss and losing cravings, then he had a heart attack, and I “lost my way”, so to speak. I piled my lost weight back on, but I’ve never regained the cravings for sweet things that I used to have. I have found this has helped very much with the plan we are now following, as I’m just not interested in having sweets, chocolate, crisps or puddings. I eat plenty of protein, vegetables, eggs, yogurt and fruit (I feel duty-bound to stick to the low fat stuff for now!) and we cook our own meals with fresh, natural ingredients. I’ve refused to use spreads, other than butter, and my hubby is happy to go along with this. I won’t buy specific “diet” foods either, and am very happy to tell anyone about the synthetic gunge in any one of them! We are both losing weight (only three weeks in), and I am really not finding it hard, mainly because of THD. In fact, other than, for now, doing low fat, what I eat is all advocated by THD. Some of the members at our group talk about how they “have” to have a chocolate bar each day, or they just couldn’t stick with it. I don’t “have” to eat anything, because I don’t have cravings. One woman was in tears because she is “addicted” to crisps. Others were filling up because they could “relate” to this “dark place”. My hubby and I find this all a little bit bizarre, to say the least, because we have no doubt what caused us to pile on the pounds, and we choose not to eat those sugary, starchy, artificial foods now. He found it a bit harder than me to start with, because he has always had a sweet tooth, and would live on Chinese takeaway curry, but he knows that this is why he is overweight. Now, he even swaps recipes with a colleague on the same plan! He has cut his bread consumption to around six slices of wholemeal a week, whereas he was getting through more than two loaves a week before – by himself! I have had about four slices of bread in the entire three weeks. Nothing is banned or limited, other than sugary, starchy, artificial foods, and you have a daily allowance for these, if you want it. As long as he’s happy on this, I’ll stick with him, but I have THD to thank for finding it easy to do so. He has lost a stone in three weeks, and I am very proud of that. He would find this “fasting” lark virtually impossible. A colleague of mine has been following the 5:2, and has lost about 3lbs in eight weeks. It doesn’t teach you about nutrition, which I think is vital, again because I have read so much written by Zoe and others who think how she does.

    • Hi Catherine – thanks so much for sharing all this. I’m so sorry to hear about your hubby’s heart attack – hopefully he’s doing better now he’s on real food. Your words will be an inspiration to those who think that they have to put up with a life long addiction to crisps – we really don’t! You could sit me next to a plate of biscuits for the next 20 years and I would never think of having one. Cravings can be beaten.

      Keep up the great work and you’re not alone in doing The Harcombe Diet at another club! The social support is valuable (that’s why we have – long may it help you
      Very best wishes – Zoe

  • I was very interested in this diet, however the more I read in the book the more confused I became with the contradictory content.. To begin with the 2 restricted days are a max of 500 calls for woman, yet the Ready Reckoner at the back of the book states max calls for the fasting days? as 1,000 cals. When I looked at the minimum requirements of food choices for these fasting days I couldn’t see how you could do this within 500 cals. this diet promotes an obsessive pattern of behaviour toward your diet and this in itself is not healthy.

  • I too can recommend the 5:2 diet for weight loss. I started on 17th September 2012 and have been following up until now. I am not gaining weight. It is gloriously simple.

    Eat 500 (woman) or 600 (man) calories on 2 days a week and eat what you want on other days.

    Thanks Zoe for your special report. It helped me a great deal and I was able to enter into the diet with eyes open. I recommend it.

    You can see my pictures at

    Best of luck whichever route you take,

  • I’ve just started reading your excellent blog. As a nutritionist I have been recommending intermittent fasting for years, with the focus on ‘intermittent’ and the consumption of foods on fast days as none, or a small amount of very nutritious foods (nutrient dense not necessarily calorie dense) to bookend the day. I think that 5:2 is too many days restricting yourself and too easy to get into an unhealthy pattern. I prefer the ‘Primal’ approach to fasting, which is to fast opportunistically when you have the urge to, or when good food choices are not available – for example when traveling, or in an all day meeting. Getting stuck in any kind of rut is not healthy or optimal – especially when the 5:2 diet recommends skimmed milk, margarine and sweeteners! Apart from the possible health concerns over sweeteners, have they not seen the studies showing that sweetened drinks promote an appetite for carbohydrate and maintain the desire for sweet foods? Great stuff Zoe, thanks for this reference. x x x

  • I’ve done both Harcombe Diet and 5:2 (the Michael Mosley version not the tosh above!!) While I lost about 11lbs on Harcombe, I did not find it sustainable and although cravings reduced, I was conscious of my food intake 7 days a week. Even though I wasn’t counting calories, I felt like I might as well have been on Weight Watchers! (Not that I ever have been). I started 5:2 in February and lost all the weight I’d regained after stopping THD, and more, 20lbs in 11 weeks. My appetite is much better, I don’t have cravings, I choose healthy, natural foods nearly all the time, I sleep well and have loads of energy (I’m running 8-10k three times a week, even on fast days). With 5:2 I can go out for a curry with my partner or eat the occasional biscuit without feeling like I’m breaking the rules! My BMI is now under 21.

  • And the fun continues! They are now trialling the 5:2 diet for type 2 diabetics! Terrific. So if we don’t succeed with this diet, we will be told it’s because “we’re not sticking to the diet” and it “must be our fault” if it doesn’t work. I’d like to know if the 600 calorie a day diet does work – it seems to have had some success, and I would follow anything which really DID work. But I don’t want more reasons from people to condemn diabetics to a living death, more reasons to look down on the obese.

    What’s the difference between an anorexic and an obese extreme dieter? The anorexic gets told to eat more.

  • I have doing the 5:2 diet and whilst the weight loss has not been massive, I have altered shape, becoming leaner round the tummy and on the thighs. I also feel very much lighter and my digestive system is working more efficiently now. After a fast day, I sleep so incredibly well – a very peaceful sleep. You claim the Harcombe diet can deliver 17lbs weight loss in 5 days. That can not be fat that is lost – it would be far too quick, and I imagine unhealthy. What I like about the 5:2 is that I really can eat what I want on non-fast days and fast days are very bearable – you can make 500 calories go a long way without too much effort.

  • I think that any premenopausal woman following one of these diets risks infertility. Just eating real food and cutting way down on the carbs will ensure continuing good health, an improved immune system and good fertility. In any case, real food tastes much better than any manufactured junk!

  • “– you will have trained your body to maintain on a lower calorie intake.”

    This is key and something many people are unable to grasp. Your body is exquisitely good at detecting calorie restriction and it will definitely make changes to compensate.

    I suspect calorie restriction is probably a better way to make people obese than overfeeding.

    If your only eating 500 calories for 2 days a week, your body can do one of 2 things. Either it can maintain its BMR in which case you will eventually reach 0% bodyfat and die of starvation, or your body can reduce its BMR to match the averaged energy intake of calories.

  • Lighter Life do a similar diet these days – but they sensibly say that it is perfect for maintaining your weight – not weight loss. Their own studies have shown that weight loss is negligible therefore they say that you can use their products on the off-eating days to ensure you get the right nutrients and you will help to maintain your weight.

    They also found that people took a couple of weeks before they stopped stuffing themselves on their eating days. eventually it calms down and eating becomes more normal – whatever that means.

    Why can’t we just eat until we are full – because of carbs. Cut those out and there is no need to take two days off a week.

  • Yes, I was doing splendidly on a LCHF diet until recently. I added in a few more carbs (natural stuff) and have been told yesterday that my weight has gone up and I have gained 10cm round my tummy!

    This despite doing a cleaning job over weekends (5 hours of continuous movement) and cycling everywhere. It looks like that contrary to popular opinion (here :-)) I can only lose weight by eating less food. Or having such a restricted diet I feel sick facing a pork chop AGAIN!

  • Hi Zoe,

    Great review of the diet, I am so glad that you found it over complicated and so obviously a 7 day diet! I thought I was going mad when I was reading the guidelines – who has the time or inclination to analyse their proportions of food to this degree? Also, the constant recommendation of low fat spread and diet drinks is the antithesis to all up to date thinking on nutrition isn’t it!

    Typical overhyped diet being serialised by the Daily Mail!



  • Hi Zoe ,great simply explained article .As a STOTT Pilates instructor and personal trainer lots of my clients have asked me about this diet and I can now safely say to them don’t bother with the misery of starving yourself !and having read two of your books recently very much recommend them to my clients to follow your advice.
    Finally an author like yourself who has spent a lot of time researching the evidence! And gives the truth not a marketing miracle .

    Look forward to your next post !
    Thanks Amanda

  • Hi Zoe,

    I’ve been reading this space for some time now, and I love your no-nonsense approach. Same for this story, however, I’d like to add something that I’ve felt holds true when it comes to dieting.

    To each his own. I don’t think labeling this particular diet as obsessive and miserable does any good to your analysis. It’s up to people to figure out which diet fits their bodies and minds perfectly. Some might feel the ever-popular Atkins Diet don’t suit them, while some might find the seemingly shocking Warrior Diet perfect.


Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.