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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!!

350 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:
HLBug · 13/07/2026 17:31

I’m also here today - back from a wayward week due to the start of the school summer holidays.

im totally out of routine and am desperate for some normality - so a FD today has been very welcome!

currently sitting on 330cals but not sure yet what I’ll do for dinner

harriethoyle · 13/07/2026 18:31

Kitchen closing on 635. I’m still starving 🤣 how did you get on @HLBug @mumofbun ?

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HLBug · 13/07/2026 19:06

Omelette for tea and closing on 692.
Good to be back Smile

harriethoyle · 14/07/2026 11:10

Signing in for day 2 of my b2b. I am bloody ravenous... Can see today being slightly higher than intended 650...

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harriethoyle · 16/07/2026 09:24

Was supposed to be doing a third FD today but just woke up not feeling it AT ALL. So have compromised with aiming for a mini - normal breakfast and FD lunch and tea. Should come in under 1000 calories I think.

OP posts:
mumofbun · 16/07/2026 17:06

I'm out drinking today... Day off coincided with 10 year wedding anniversary and we are having a wonderful time. My weight in yesterday was great though so I'm allowing some balance!

harriethoyle · 16/07/2026 19:41

How lovely @mumofbun - enjoy it!

kitchen closing on 1037. I’ll take that!

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harriethoyle · 20/07/2026 19:40

Skidding in at the last minute to tell you that I’m on 698 and back tomorrow for a b2b!

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harriethoyle · 21/07/2026 08:14

Signing in for day 2 - anyone with me?

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HLBug · 21/07/2026 17:45

I’m here! Managed 742 yesterday and will probably close on 864 today. Last week I FD on Monday then got a bit waylaid so ended up having a few “just over mini” days to compensate.

HLBug · 21/07/2026 17:50

Here’s a random question for you all. I take the mini pill continuously so I don’t get a regular period. A handful of times over the year I’ll get a bit of spotting, and I very rarely get an actual period (breakthrough bleed I think it’s called). I’ve noticed recently that when I stop fasting for a bit and then restart (or indeed do anything else to limit calories - doesn’t need to be fasting) that I’m more likely to get spotting or a bleed a few days later. Does anyone else have a similar experience?

harriethoyle · 21/07/2026 20:17

Kitchen closing on 861.

I haven’t noticed that @HLBug but I run microgynon in the same way and notice I have a breakthrough bleed for a couple of days every 3-4 months. Might just be coincidental?

I’m about to change to the progesterone only pill because I’m starting HRT. Bit apprehensive actually!

OP posts:
mumofbun · 22/07/2026 09:42

Sorry I've been AWOL! School hols have killed the routine...I'm going to try for a FD today. We go on holiday on Saturday so I had grand plans to do a few and a load of classes but not actually managed that!

TeaRose29 · 23/07/2026 09:19

Emergency mini for me today! 🤣🤣

harriethoyle · 27/07/2026 10:34

Morning all, I’m on a b2b after an extremely indulgent and boozy weekend. Aiming for 3 FD and off the booze until middle of August when we have friends staying from abroad.

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harriethoyle · 27/07/2026 21:16

Kitchen closing on 679. Back tomorrow!

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mumofbun · 28/07/2026 16:09

I'm in Spain so will report back next week...

harriethoyle · 30/07/2026 10:25

Oh Spanish food is SO GOOD @mumofbun - enjoy!

Did a mini yesterday and another today, after unexpected travel on Tuesday led to abandonment of FD. Should come in around 1000 today I think and went to the gym last night. Holding steady at the moment which is good!

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TeaRose29 · 31/07/2026 09:33

Well done @harriethoyle. I’ve been experimenting with 16.8 with only a small calorie deficit and eating most of my calories at lunchtime, and the weight is falling off!

harriethoyle · 31/07/2026 09:57

Do you not get super hungry before bed @TeaRose29 ? sometimes on day 2 of a b2b I can't sleep for hunger and lie awake fantasising about breakfast! 😂

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TeaRose29 · 31/07/2026 13:45

Hi @harriethoyle . Firstly I’m eating about 1500 calories a day which is much more manageable, and secondly I never feel hungry in the morning so I don’t eat until lunchtime, often at 1 or 2pm, and then I have something light, say yogurt and fruit, at about 7.30pm. So no, I don’t feel particularly hungry at bedtime. I also eat low carb high protein, which I think helps.

harriethoyle · 03/08/2026 09:03

Morning all - signing in for day 1 of a b2b. Gym class booked for tonight too. Still on much reduced alcohol consumption and my weight is fluctuating so much less! Sad but true 🙈

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HLBug · 03/08/2026 12:46

Signing in for a Mini - school holidays meant no FDs this week and I’ll be in the same situation next week too, argh.

Aiming for 2 (hopefully) 3 Minis this week.

harriethoyle · 03/08/2026 15:02

Honestly @HLBug I think 3 minis are just as good as 2 FD - also means you're virtuous on more days!

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harriethoyle · 03/08/2026 19:18

Kitchen closing on 830. Back tomorrow!

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