5:2 Fast Diet Tips Part Two and Fish Pie

Tips for 5-2 Diet Fast Days and a Low Calorie 5-2 Diet Fish Pie.

The 5:2 Diet or Fast Diet has become very popular in the UK since Michael Moseley’s programme on Horizon.  For me, while there may be some secrets to intermittent fasting, the reason the 5:2 diet works and helps you lose weight, stay healthy and live longer is common sense.

5-2 fast diet fish pie

For two days a week (or more if you chose to try alternate day fasting), you need to think about what you are eating and keep your calorie count to under 500 for a woman and under 600 for a man.  That means you really can’t drink any alcohol and, if you want to avoid feeling very hungry you need to be careful about the food choices you make.  For me, at least, the result is that the next day cravings for sweets, alcohol and even chocolate(!) diminishes

A few tips to make life easier if you are trying to follow the 5:2 fast diet.

  • Drink plenty of black or green tea, herbal teas or water.  If you really don’t like them, then black coffee in moderation will be fine (or save  40 calories for some skimmed milk).  If you feel REALLY hungry, fizzy water or zero calorie fizzy drinks will temporarily work.
  • Keep packets of low calorie instant soup (I like miso soup) on hand.  They are generally around 50 calories but I find a cup of miso soup really does make me feel full.  I have friends following this diet plan who drink hot bovril for the same reason.
  • If you don’t normally eat breakfast (like me), then don’t do so on a fast day.  If you are a breakfast person, recommended ideas are a boiled or poached egg, porridge made with water or zero fat yoghurt with some fresh fruit.
  • If you plan on cooking rather than using ready meals (personally I find I can create much more filling dishes myself than those I buy in the supermarket), invest in 1cal oil spray and use that for stirfries, softening onions etc.  It’s very easy to add too much oil or butter to a dish and really raise the calorie count
  • Try substituting lower calorie ingredients for traditional ones so that you don’t have to stop eating your favourite dishes.  The fish pie below uses no butter in the white sauce and the mash is a mixture of celeriac and cauliflower.   It is light, tasty and very warming on a cold winter day.  In the same way, using venison instead of pork sausages and white fish instead of salmon will help keep the calories down.  And eat plenty of low calorie vegetables – steamed broccoli, cabbage, cauliflower, mangetout, asparagus and courgettes for example.
  • Remember, you only need to do this for two days of the week…for me, that’s what really helps me keep going.  I think the best diets are ones which can become a lifestyle – the 5-2 fast diet works for me in a way no other diet has to date.

5-2 Fast Diet Recipe Fish Pie

Serves 4
Prep time 20 minutes
Cook time 15 minutes
Total time 35 minutes
Allergy Fish, Milk
Meal type Main Dish
Misc Serve Hot


  • 300g Fish (a mixture of smoked and fresh - I used haddock, smoked haddock and salmon)
  • 1 Shallot
  • 4 Tomatoes (skin removed and chopped)
  • 40 ml Skimmed milk
  • 300g Cauliflower
  • 300g Celeriac Root
  • 1 teaspoon Cornflour
  • 1 tablespoon Low fat creme fraiche
  • 2 Bay Leaves
  • 20g Parmesan or strong cheddar (finely grated)


Step 1 Peel and cube the celeriac. Put in a pan of cold water with a little salt and bring to the boil. Simmer for 10 minutes before adding the cauliflower broken into florets. Cook for a further 5-8 minutes till the cauliflower is soft
Step 2 Drain the mixture and leave to dry a little with the lid off before mashing with a potato masher, or blitzing with a stick blender. Season with salt and pepper and leave to one side
Step 3 Put the fish into a pan with the milk and bayleaf and heat the milk to simmering point. Cook for a minute or two, then cover and take off the heat and leave for 5-10 minutes.
Step 4 Pre-heat the oven to 170c. Remove the fish from the pan and break into largish flakes
Step 5 Remove the bay leaves from the milk. Mix the cornflour with a little water or cold milk and add to the pan. Bring the mixture back up to the boil and cook for 4-5 minutes till thick and creamy. Take off the heat and add in the creme fraiche.
Step 6 Soften the shallot in a small pan sprayed with 1cal oil, then add in the tomatoes and reduce down by about a third.
Step 7 Make up the fish pies as one large pie (serves 4) or 4 small ones by dividing up the fish mixture, seasoning well with salt and pepper and then pouring over the sauce. Add a layer of tomato mixture and then top with the mashed celeriac and cauliflower
Step 8 Grate a little parmesan or strong cheddar on top of each pie and place in the oven for 15 minutes (individual pies) or 20 minutes for one large pie.
Step 9 Serve with steamed green vegetables.

This recipe cuts the calories of a traditional fish pie (around 500) down to under 300, depending on the mix of fish you use.   Mine was lovely wild fish from DelishFish in Scotland and I think using a good smoked haddock DOES make a lot of difference to how well this pie turns out.  Salmon is actually relatively high in calories, about 200 calories per 100 grams, so if you really need to keep the calories down low, use a different white fish (cod, hake or monkfish for example) or prawns instead (you shouldn’t need to poach the prawns, just add them into the fish mixture at the last minute).  It is genuinely delicious, the very light sauce binding the fish together with a topping that is actually rather tastier than potato mash in my view, makes for something quite special.

The method of making mash with celeriac and cauliflower mixed worked very well and I’m planning on trying a shepherds pie using the same mixture.  I wanted to reduce the calories in the mash down as far as possible while keeping a mixture that wasn’t too watery.  Because the mix is very light, you really don’t need to add cream or butter (though of course you could if you were not doing a 5-2 diet fast day).  The quantity I’ve given makes enough topping for four portions and works out at about 50 calories per portion.  By comparison, the same quantity of mashed potato by weight would be be a third more.

5-2 fast diet fish pie

I feel better and I hope look better from following the 5-2 fast diet for a few months.  I am not finding it hard to do, other than the occasional hunger pang.  I’m working on reducing the calories in some of my favourite recipes simply so that I can enjoy them myself on 5-2 diet fast days.  But some of them, like this one, are quite nice enough to eat anyway whether or not you are trying to lose weight.

Good luck to everyone who is also doing the 5-2 fast diet – do feel free to comment or add your own tips here.

If you enjoyed this post, please consider leaving a comment or subscribing to the RSS feed to have future articles delivered to your feed reader.


    • says

      I don’t object to eating a vegetarian meal every so often. And a lot of the home made soups I make ARE vegetarian (and I think my most popular recipe on here is mushroom goulash!). But I like meat and fish too.

    • says

      It depends on the proportion of fish you use. Salmon is around 200cals per 100g. while Haddock is half that. So, if you make this dish up using 300 grams of fish, split equally between the three varieties I’ve listed, the fish itself will account for around 100 calories per serving, the sauce around 50 calories and the topping a further 80-100 calories (e.g. 250 calories). The main calorie savings come from the topping of tomato and cauliflower and celeriac mash and from using a much lighter sauce for the fish than would be traditional.

  1. Kerry says

    Wondering what you mean by this: ” For me, at least, the result is that the next day cravings for sweets, alcohol and even chocolate(!)” Is part of the sentence missing? You mean you have a lot of cravings the next day?

    • says

      I’m sure you realised that somehow a word had been dropped from the end of the phrase. I’ve corrected it now. I suspect it happened, along with the image error, when we transferred the site to a new theme last week

  2. says

    Thankyou for sharing some great tips and great recipes! We had a similar steamed thai fish tonight and I will try the pie tomorrow! Thankyou for all your time in putting this together. Bron, starting the 5:2 tomorrow!

  3. Karen McDonald says

    Hi Fiona, I have been doing the 5:2 diet for a few weeks now, getting results so will continue but always looking for new ideas on what to eat. Also it would be good to hear how other people are managing their diets. So if you can send me the facebook links that would be great .

  4. Mary Ann says

    Hi Fiona – A brand newbie from the States. I just did my first fast day yesterday and it was tough, but I’m so proud I made it. I didn’t plan well, so I went online today and found your website. It’s now in my favourites!! Thank you for this fish pie. I think my husband (who is not fasting) will equally find it enjoyable.

Leave a Reply

Your email address will not be published. Required fields are marked *