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Fasting / 5:2 diet

Talk about intermittent fasting and 5:2, including what’s worked for others. Mumsnet hasn't checked the qualifications of anyone posting here. You may wish to speak to a medical professional before starting any diet.

5:2 thread 104: Here's to FAST-ening those jeans!!

243 replies

harriethoyle · 10/03/2026 19:38

Welcome to the continuing thread for those following 5:2 or other forms of IF (Intermittent Fasting) such as 4:3, ADF, etc.

Basically it is 2 very low cal days ("fasts") per week - which need not be consecutive - and eat "normally" to maintain on the other 5 days.
For those who have dieted or maybe overeaten for years, eating "normally"
means roughly the number of calories your body needs to maintain - NOT reduce - its weight (see TDEE calculator below).

IMPORTANT
If you have had past diagnosed Eating Disorders or serious MH problems you should NOT do 5:2 or any other kind of fasting.

JARGON alert
16:8 is a different type of fasting, which can be combined with 5:2.
Daily zero-cal fast for 16 hours and eat within an 8 hour window. To lose weight, this needs a weekly calorie deficit as well
b2b (optional) back-to-back / consecutive fast days, each with an increased allowance of 650 calories instead of 500
BMI (Body Mass Index) healthy range is 18.5 - 24.9 for Caucasians. Upper limit may be 22 for some of Asian origin.
FD = single Fast Day: aim for 500 calories (600 for men or 25% TDEE whichever is higher) or 1000 cals for BF
No alcohol or junk on FDs
Even if you exercise strenuously, do NOT increase FD cals to allow for exercise
MFP = My Fitness Pal, a useful App or website to track food & drink calories
miniFD = MiniFD, tel:850-1000 850-1000 calories, no alcohol or junk
NFD = Non-Fast Day, averages around TDEE
NSV / LSV = Non Scale Victory / LifeStyle (change) Victory, e.g. compliment, smaller waist, clothes size
SV = Scale Victory
TDEE = Total Daily Energy Expenditure, the average number of calories you burn in a day, is calculated from your current weight, height, age, activity level.
Aim to average about this for NFDs.
WOE / WOL = Way Of Eating / Way Of Life. We say this instead of "diet", to emphasise that we must make a permanent change in how we eat, to maintain our new healthy weight long term.

Jump in and say hello!!

OP posts:
mumofbun · 29/04/2026 08:26

FD 2 of the week

I've got my hydration sachets at the ready 🤣

TeaRose29 · 29/04/2026 09:56

Well done @harriethoyle and @HLBug ! @mumofbun well done on your loss. It has also taken me since January to lose 6 pounds, but I’m very happy with that, as the last few pounds are always the hardest, and I feel that I’ve consolidated a fat loss, if you know what I mean, rather than it being water weight or something.

I’m going for a protein mini today. I’m playing tennis later and I know it will be a very physical match, so I’ll need some fuel for that!

harriethoyle · 29/04/2026 18:53

Kitchen closing on 713. Happy with that for day 2!

OP posts:
harriethoyle · 29/04/2026 18:54

How did you get on @mumofbun @TeaRose29 ?

OP posts:
mumofbun · 29/04/2026 19:03

@harriethoyle 788 which I'm happy about considering I had a protein yoghurt which I didn't realise would wipe out a large amount of calories!

mumofbun · 29/04/2026 19:04

Also no headaches so far!

harriethoyle · 30/04/2026 08:27

I’ve got your headache @mumofbun 😟 absolute thumper I can’t shift! Been to the gym this morning and hoping the paracetamol will kick in soon…

OP posts:
TeaRose29 · 30/04/2026 08:37

I was very tired and hungry when I got back from my tennis match. (It was exhausting as we were 2 women against a man/woman pair - we lost 6-4 6-4 which we were pretty happy with, but it was hard work!). I could have devoured loads of carbs, but thankfully didn’t - ate more than intended but it was mainly protein. We are eating out at a Turkish restaurant tonight, so I’ll have another protein day today and maybe a mini tomorrow.

well done @harriethoyle and @mumofbun !

mumofbun · 30/04/2026 16:31

harriethoyle · 30/04/2026 08:27

I’ve got your headache @mumofbun 😟 absolute thumper I can’t shift! Been to the gym this morning and hoping the paracetamol will kick in soon…

Oh no!! Hope the paracetamol helped!!

harriethoyle · 05/05/2026 08:33

Morning all! Anyone fasting with me today? Can only do 1FD this week so I’m going to make it count… gym this morning already and dog walk tonight

OP posts:
harriethoyle · 05/05/2026 20:53

Kitchen closing on 682 and tomorrow’s work lunch has been cancelled so I can do a b2b - hurray!

OP posts:
TeaRose29 · 06/05/2026 09:02

Well done @harriethoyle ! Protein mini for me today.

harriethoyle · 06/05/2026 09:07

Checking in for day 2 of b2b… anyone else with me and @TeaRose29 ? aiming for a similar day to yesterday, chilli and broccoli for dinner 🤤

OP posts:
harriethoyle · 06/05/2026 20:39

Kitchen closing on 757. Have been ravenous today so taking that as a win!

OP posts:
mumofbun · 07/05/2026 07:48

Well done @harriethoyle I've had a bad week - we weren't very prepared so everything has fallen off! I have managed a couple of classes though

TeaRose29 · 07/05/2026 09:13

Total fail yesterday! Felt dizzy to the point of almost fainting! Trying again today 😊. Well done @harriethoyle !

harriethoyle · 07/05/2026 14:13

Finally below 70kg - it's been hard work to get back there after my extended stay at the in laws. Might try for 3 FD next week and really capitalise, we've very little on socially so it would work quite well!

Good luck @TeaRose29

OP posts:
TeaRose29 · 08/05/2026 09:11

Well done @harriethoyle ! I had a much better day yesterday, which included over 14k steps, and weighed in at 9.13 1/2, which is a new low for me in several years. Going for a high protein day of around 1500 calories today.

MadMazie · 10/05/2026 00:32

Hello, I've just found out that I have high cholesterol which has given me the kick up the bum I need to lose weight.
I've successfully lost weight with 5 2 before but have put some (not all thankfully) back on.
BMI is currently 30.5 and my first goal is to get it below 30.

One thing that I struggled with last time was terrible insomnia on fast days. Has anyone managed to overcome this?

Also, I've read that 800 calories are now recommended on fast days, is this correct? When I last did it it was 500 only.

harriethoyle · 10/05/2026 18:21

Hi @MadMazie - welcome! A FD is 500-600 calories, a b2b you aim for 1300 across the two days with at least 500 cals per day. A colleague of mine came off statins through fasting so you’re in the right place!

OP posts:
MadMazie · 10/05/2026 23:54

Thanks @harriethoyle
I'm not looking forward to it but weight loss has now become about more than vanity to me so I feel motivated.

I have some homemade chicken stock so I'm planning on making a warming garlic and chilli broth with that to drink before bed so I can hopefully sleep.

I have a 300 calorie m&s meal for tea and will make up the rest of the calories with egg, cottage cheese and cucumber.

I've also stated psyllium husk to help lower cholesterol which is actually quite filling so hopefully that will help.

HLBug · 11/05/2026 08:14

Morning all - logging in for a Monday FD. Didn’t manage anything last week due to bank holiday weekend and then work events. Went to a ceilidh at the weekend and danced my socks off though, so I’m hoping that has helped balance out the week a bit!

mumofbun · 11/05/2026 09:29

@HLBug also fasting today (after not managing last week...) will have to see how i go though as it's the first time i've booked an exercise class on a FD so if i feel sick i might have to eat something extra!

Welcome @MadMazie - broth sounds like a great idea! Do you take any magnesium? it's meant to be good for sleep and helped my mother in law with night wakes.

harriethoyle · 11/05/2026 10:22

Morning @HLBug @mumofbun - am also fasting. Already feeling hungry which doesn't bode well..!!

OP posts:
HLBug · 11/05/2026 14:28

Oh I’ve just seen it’s National Eat What You Want Day…..! Not so much for those of us fasting!!

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