5:2 Diet review

The fast dietBackground

The 5:2 fast diet was popularized by TV presenter and medical journalist Dr Michael Mosley for its health benefits and weight loss.

The Fast Diet by Dr Michael Mosley and Mimi Spencer 

Diet summary

Based around Intermittent fasting, it recommends you eat well for 5 days a week, and then reduce calories to 500 (for women) or 600 (for men) on 2 non-consecutive days.

The good bits

  • As you would expect from a book written by a Doctor, the science and background to the benefits of fasting are well researched, well communicated and generally excellent.
  • There are lots of good tips for making the program work, along with personal examples making it feel more human
  • Includes recipes and ideas of meals for the fasting days
  • Author’s experiences add to its accessibility, making you feel that if they can do it so could you.

Not so good bits

  • My main issue is that it isn’t real fasting if you are eating 500 calories, and as a result you are missing out on some of the fat burning effects by not being fully fasted.
  • No real program and relies on its flexibility but suspect some would have preferred a more clearly laid out structure and plan.
  • You are still having to faff with counting calories (which can cause confusion especially on the non fasting days – clear when you read Facebook group comments)
  • Whilst it talks about eating a low GI diet, it could have focused more on the healthy eating.


  • A well written and great introduction to intermittent fasting, but should have gone just a little bit further, and taken its own science to the proper logical conclusion, rather than diluting it.
  • Would highly recommend it for first timers, but think with a few minor tweaks it could have been a classic


Effectiveness             4/5

Simplicity                   4/5

Sustainability             5/5

Healthiness                4/5

Overall:                       17/20 

Other Books about the 5:2 Diet:

The Fast diet recipe book by Mimi Spencer and Dr Sarah Schenker

The 5:2 diet book by Kate Harrison

The Ultimate 5:2 Diet Recipe Book by Kate Harrison

The 2-day diet by Michelle Harvie and Tony Howell

The 2-Day Diet Cookbook by Dr. Michelle Harvie and Professor Tony Howell


Please note:

Whilst my reviews are entirely independent, I am an amazon affiliate and will make a (very) small commission from any sales as a result of clinking on the links.



7 tips to successful fasting

Fasting empty plateFasting has been around for as long as man has walked the earth, and is in my opinion, the most effective, healthiest, quickest and easiest way to help you lose weight. People are often surprised at how much easier it is to eat nothing than to eat small meals that leave you hungry and then battling hormones and blood sugar.

However in modern society, as with many things, anything easy is rarely worthwhile. So this is my guide to how to make your fasting day as painless as possible.

1.    When to fast

Choosing the right days to fast is vital, ideally you want to pick days when you are busy and have the most control over your environment with the least temptations. So weekends are often best avoided, as are days when you have an important work lunch or a party. Days out are also bad, as you will often be surrounded by temptations (ice cream, my own personal vice, at the cinema is a good example)

The time of day you do your fast is a personal choice. For me, start after your dinner in the evening (ideally an early one), sleep, skip breakfast, skip lunch, eat dinner 24 hours later. Job done.

2.    How long to fast

24 hours seems to be the optimum time, balancing the effect of the fast and the ease in which to complete it.

The great thing about 24 hour fasting, is that by timing it right, you still get to eat everyday.

3.    How often to fast

Anywhere from 1 to 3 days per week. But avoid consecutive days. If you are just starting and are highly motivated, 3 days is great (so Monday, Wednesday and Friday), but not for more than 28 days, and no more than twice a year as you don’t want to burn out.

January is always a good month after the excess of the holiday season, as is the month before that beach holiday or wedding.

Otherwise stick to 1 or 2 days per week depending on how you feel

4.    Surviving the fast

If you have chosen the right day etc you will already be most of the way there. On the day, you need to drink a lot of water (even better add a dash of lemon). For me, a large glass of water and a black coffee when I wake up seems to persuade my body that it isn’t hungry.

Black tea and Coffee are both extremely effective at putting off any hunger pangs.

Distract yourself. Training at the gym seems to cure most hunger pangs.

Once you have done a fast you will know for next time, when your body starts to complain, so plan ahead and do something before it hits.

5.    Hitting a wall

Sometimes 20-ish hours in, you will hit a wall and feel that you can’t go any further. If this happens, make yourself a protein shake. It will fill you up and get you through to the end. Whilst it’s not a strict fast at this point (depending on who you listen to anyway, as the warrior diet and 5:2 both seem to allow limited eating during a fast) it is better than finishing your fast early.

6.    After the fast

Eat normally and properly (ideally Paleo/low carb), don’t binge but eat until you are full.

7.    Expectations

Depending on a huge number of factors, including age, sex, bodyweight, physical activity etc etc. You should expect to lose between 0.5 – 1.5lbs per week for every days fasting. So for a month of 3 days per week fasting, that’s around 12lbs.  You can add another 50% to that figure if combined with eating well (see above) and perhaps another 25% with a good exercise plan (Strength training is most important for good body composition i.e. burning fat not muscle and maintaining your metabolism so that you don’t put the weight back on the moment you stop)

Finally, good luck and enjoy the journey.

Richard aka The Fat Executive

Important note: Before you fast make sure you are healthy enough to do so. Please check with your doctor first and anyone with a history of eating disorders, low blood pressure or any other medical condition should avoid it. The advice on diabetes is mixed so suggest it is best avoided unless under medical supervision.

Fasting: An introduction

Simply put, fasting is not eating, and intermittent fasting is not eating for short periods (typically between 16-24 hours) but regularly (1-3 times per week).

Fasting has been made increasingly popular of late by lots of media coverage and books including: Eat-stop-Eat, 5:2, Lean Gains etc.

Most people are filled with horror at the thought of not eating for any length of time, but are often surprised at how easy it is, and find it much easier than just eating less.

The reason that it is easier, is that unlike when you eat, your blood sugar stays level, and Insulin (one of the hormones that makes you hungry) doesn’t spike then drop, which is why you feel hungry 2 hours after you eat, especially carb and sugar heavy meals such as breakfast cereal.

It is also simple to do and understand, extremely flexible (so you can fit it in around your schedule to suit your lifestyle) and highly effective.

Not only is fasting easy, it has huge health benefits including:

  • Decreased fat and body weight
  • Maintains muscle mass (and hence metabolism – how many calories you burn doing nothing)
  • Lowers blood glucose
  • Releases and burns stored fat (Lipolysis and Fat oxidization)
  • Reduces Cholesterol
  • Reduces system Inflammation (Reducing the risk of certain cancers, diseases, Arthritis, Asthma, Cardiovascular disease, diabetes, effects of aging, and many others )

There are also many hormone benefits including:

  • High levels of growth hormone, (Burns fat, build muscle, lowers belly fat)
  • Lowers insulin levels and increases its sensitivity (Stops you storing fat and reduces the risk of diabetes)
  • Increased Glucagon levels (fat burning, the opposite of Insulin, maintains blood sugar, reduces Cholesterol)
  • Increased norepinephrine and epinephrine levels (happy hormones, that make you feel more alert and awake)

Fasting methods

There are a number of ways to fast,

  • Eat-stop-Eat, works on one or two 24-hour fasts per week.
  • 5:2 suggests reducing your calories to 500 on 2 days a week.
  • Lean gains, has 16-hour fasts every day.
  • Warrior diet, is one main meal per day but with multiple protein shakes or small meals.
  • Velocity diet is 1 solid meal per week!!!! The rest of your food comes from protein shakes and supplements.

My recommended method

Having tried several methods, and spoken to lots of other people about their experiences. My findings are: Velocity is very hard. Warrior can lead to weight gain and isn’t strict enough (though it can work for some). Lean gains is good but hard to stick to long term. 5:2 is good, but isn’t fully fasted. Eat stop eat works well.

For me, the easiest way I have found to fast is to finish your evening meal then not to eat for 24(ish hours). Then eat the next days evening meal. This way you eat every day and can sit down with your family to enjoy a meal together.

The effect of 2 days fasting is to typically reduce your weekly calories by 15% and you should expect to lose 2-3 lbs a week.

Top Tip: Drink lots of water, plus hot black coffee/tea really helps keep any hunger pangs at bay.

I would also recommend you combine fasting with a healthy diet that will also help your weight loss, specifically a Paleo diet (see other posts), and training (exercising with purpose).

If you train on your tasted day (highly advised, many health benefits plus good for distraction and appetite suppression) then I suggest a protein shake an hour after doing so, but nothing else.