Tips for starting the The 5:2 (Fast) Diet

I’ve seen a few people around lately asking about what diets worked for people, and even specifically about the 5:2 diet, also known as The Fast Diet. So I thought I’d write a little piece about my experience with the diet and some tips to help you if you decide to try it.

I first heard about the diet in February 2013. I had just returned to work after having my first son, and I weighed about 200 pounds (just over 14 stone). For me, that was not a comfortable weight. At lunch one day, some of my colleagues started talking about this diet where you eat just 500 calories (600 if you’re a man) for 2 days of the week, and eat normally (2000 calories/day ideally) the rest of the time.

I thought it sounded like such a ridiculous fad diet, and possibly even dangerous. I also thought I would be extremely grumpy if I didn’t eat enough in a day, and possibly even wouldn’t be able to function.

And because this is the sort of person I am, I decided to read a book about the diet. Just so I could tell my colleagues that I read it and still think it’s rubbish. So I bought the Kindle version of The Fast Diet by Michael Mosley. He is the guy off of the TV show, Trust Me, I’m a Doctor, and one of the originators of the 5:2 craze. He tested out the science of intermittent fasting by doing it on himself, and the book lays out his findings.

It was utterly convincing. I gave the book to my husband – who is the biggest sceptic you could ever meet – and he thought it was great too. We decided to do it together.

It took me about 9 months to lose 20 pounds (about 1.5 stone) the first time I tried it. Then I got pregnant with my 2nd son and gained it all back. I started again when I stopped breastfeeding my 2nd, and again lost the 20 pounds. So the weight loss is slow, but that is what makes it sustainable. You will also see from the book that there are other reported health benefits, such as lowering your risk of cancer and diabetes.

I don’t have much in the way of before and after photos, as like a typical mum, I’m not in many of the pictures, especially full-length ones. But here I hope you can see the difference in my face, from April 2016 to now.

So I’ll let you read the book for yourself – it’s a quick read – but here are two lists from me. One with the pros and cons of the diet (and I think the pros far outweigh the cons), and another with a few tips for getting started.

Pros & cons of The Fast Diet


  • It works around your social life. You don’t have to be the one who can’t drink or have anything on the menu on your night out. Just plan your low-calorie days to work around your life. Ideally, they should be on non-consecutive days of the week, but it doesn’t really matter.
  • It doesn’t cost a lot of money. So many diets require subscriptions, or for you to attend groups or buy specialty foods. This diet isn’t trying to sell you anything (except maybe the recipe books, but they’re not necessary). We found that we even spend less money on food generally because we are eating less!
  • It can work around your family. You don’t need to eat a separate meal from everyone else. The diet works on the premise that in order to keep yourself feeling good on your low-cal days, you should eat mostly plants and protein. So a fast day meal might be some chicken and vegetables. This can easily be adapted for the rest of your family by adding some rice or potato. And, once again, it’s only twice a week – so it won’t really hurt the non-dieters to just eat the same as you.
  • It resets your eating habits. I found that it changed the way I ate even on my “normal” days. I’m less hungry all the time and my appetite is smaller. I don’t get ridiculously hungry between meals and mostly forget to snack! I’ve found it’s easier now to ask myself if I’m really hungry before I eat, rather than just bored or emotional.
  • It improves concentration. You might think that not eating will make you tired or cause you to have difficulty concentrating. But I (and many on the diet) have found that I concentrate better on my fast days.
  • It’s a diet for people who love food. I haven’t had to give up a single food that I love. I’m still allowed cake, chocolate and alcohol! It’s only 2 days/week that I restrain myself. And there are still delicious things to eat on those days, with just a bit of effort. Just don’t totally binge on your non-fast days.
  • You don’t have to obsess over counting points/calories/planning meals, etc. I’ve tried loads of other diets, like Weight Watchers, and if anything they made me more obsessed with food. Constantly counting calories and thinking about everything I put in my mouth is not for me! On this diet, I just plan 2 low-cal meals per day for 2 days per week.


  • It still requires willpower. I’m not going to lie. It’s not always easy when, for example, your neighbour drops by on a fast day with a beautiful piece of chocolate cake. Or when you’re having a really bad day. But just try and wait until tomorrow to indulge. And if your willpower fails, you can always fast on a different day!
  • It still requires planning. You do have to be careful about what you eat on fast days. You need to eat vegetables and protein in order to feel full. Crisps, chocolate or other junk food is going to use up your calories quickly and leave you starving.
  • The weight loss is slow. I only lose about 2 pounds per week. And some weeks nothing. It did take me about a year to lose those 20 pounds. But they say that the most sustainable weight loss is when you’ve lost it slowly.
  • Sometimes I feel cold or get a headache. The headache means I’m not drinking enough water. You get lots of your water from food, so you need to drink more if you’re eating less. I think the cold is just par for the course. Cardigans and hot tea seem to fix it!


Tips for getting started and carrying on

Think about when you’re going to eat on fast days

Some people have breakfast and then eat again at dinner time. Some people starve all day and eat all their calories at dinner time. I like to eat lunch and dinner. I find it easy to skip breakfast, and actually that eating breakfast makes me more hungry over the day. So experiment and see what works for you. Also think about what fits into your lifestyle.

Think about when you’re going to fast

As I mentioned already, this is totally flexible and can be different from week to week. Just consider whether you find it easier doing some things than others. I find it difficult when I’m with my kids because they’re constantly eating, but if I’m working I just focus on that and forget about food.

Think about what you’re going to eat on fast days

It’s good to start out with a few meals planned. If you’re having 2 meals in the day, it’s probably best to have one 200-calorie one, and another 300-calorie one.

You can get lots of recipes for free on the internet by searching for 5:2 diet recipes or recipes with the calorie value you’re looking for. The Hairy Bikers do some good ones. I also highly recommend the Fast Diet cookbooks, The Fast Diet Recipe Book and The Fast Cook. There are loads of other books out there though.

Finally, it’s also worth noting that you can eat convenience food on fast days. If I’m at home, my lunch will usually be two eggs quickly scrambled with 1-calorie cooking spray and no milk. I stick some salt and chili sauce on top for a quick 200-cal lunch. There are many tinned soups that are 200 calories (Baxter’s Hearty have a few nice chunky ones). You can eat a pretty massive amount of salad with chicken or tuna on top for 200 calories. And you can even get diet microwave ready meals.

I also work in London two days per week and buy lunch out. Pret a Manger, Itsu and Crush all list the calories of their food in the shop so you can pick something appropriate. Pret’s Tuna Nicoise salad with a squeeze of lemon and salt is very filling and less than 200 calories. You can also check most food shop’s websites to see if they have any low-cal options.

Drinking is your friend

No, I don’t mean booze on this occasion (sorry). I mean keep yourself hydrated on your fast days. Keep a bottle of water with you. You can even use one of those fruit infuser things to keep it interesting. Sparkling water with a dash of lemon juice is a good option. You can drink unlimited coffee, tea and herbal tea, as long as you don’t add sugar. If you add milk, try to be sparing as this can rack up the calories. You can use artificial sweeteners if you really need sweetener, but it’s better not to.

If I’m really struggling on a fast day, I do give in and have a diet (zero calorie) soft drink. This is not encouraged but allowed. The sugary flavour really helps me feel fuller.

Get support

See if your partner or a friend will join you at least in eating a fast day meal even if they don’t fast all day. It will be good for them too and great to have support. I also recommend The Fast Diet website. It’s got forums where you can connect with other Fast Dieters and even track your progress if you want.

Be kind to yourself

I’m not going to lie. The first 2 weeks can be tough. But if you stick with it for that long, it will get easier. And if you have a bad week or are sick and can’t do it, this diet has absolutely no guilt. Just pick up fasting again when you’re ready.

Are you convinced?

I should mention that I’m not trying to sell you anything here. This is NOT a sponsored post and I have nothing to gain from you going on this diet. I just wanted to share what worked for me (and is still working, albeit slowly), after years of unsuccessfully searching. I hope you’ve found this useful, and if you have any questions, I’ll be happy to answer them in the comments.

Please note that this is not medical advice and you should check with a doctor before starting a new diet plan.

Life According to MrsShilts

Author: The Mum Reviews

Writing about women's health and wellness (especially for mums) as I try to stay sane in my crazy life.

15 thoughts on “Tips for starting the The 5:2 (Fast) Diet”

  1. Ah thank you so much for writing this up! I’m seeing so many more positives than negatives from this. It came up because my nurse suggested it and I kind of thought if a health professional is suggesting it then there must be a lot of good! I’m going to commit to this I think and on my higher calories add in some cardio workouts to help with the weight loss!

    Liked by 1 person

  2. One of my recent lecturers at uni was one of the researchers who developed the original 2-day diet as part of a breast cancer prevention method, and until I heard her speak I was very skeptical about 5:2. Now I’ve read the research on intermittent fasting I’ve been proved wrong…but I don’t think it’s something I could ever do! I get shaky if I miss breakfast, let alone fast for long periods and limit my calories so much. But with dieting, I always think it’s what is sustainable, so if it works for you and is healthy then it can only be a good thing! #slimmingsunday


    1. Thanks – we are all different and the same thing is not going to work for everyone. I know people who have done so well with things like Weight Watchers or Slimming World but I can’t do them as I feel they take over my life!


  3. This is the only diet I can possibly do, like you say Weight watchers and the like do just turn me into a food obsessive!! #EatSleepBlogRT

    Liked by 1 person

  4. I saw this on Michael Moselys TV show but although I loved the idea I just couldn’t do two days of fasting as I know I would binge on the other days. It would be great as a maintenance diet though #SlimmingSunday


  5. Really interesting! I’m constantly looking for sustainable diet plans. Weight loss is just so hard and it seems the harder I try, the harder I fail 😦

    I’ve just written a post about how fed up of being overweight I am. I’m definitely going to look into this a bit more!


    Liked by 1 person

  6. I needed to read this today. I’m currently 3 weeks into a #dechox where I’ve given up chocolate for a month. I hoped it would kick start some needed weight loss but instead I’ve gained! I’m so annoyed. I used to be an amazing dieter but since I had my son a few years ago it is so hard! I’m going to try this diet! Thanks for sharing #EatSleepBlogRT


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