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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:
HLBug · 19/05/2026 18:38

Never heard of MBT @tearose- I’m off for a google

harriethoyle · 19/05/2026 18:47

I’m closing on 793 which is a bit high but I had an emergency slice of toast at 3.30 because I was sooooo hungry!

Back on Thursday for a mini if my work course catering makes it possible…

OP posts:
Lucylurkery · 19/05/2026 19:00

Thanks @TeaRose29 I’ll give them a look. I had fit flops in the past but these sound better. Every bit helps. I am hoping getting some weight off will help.
well done harriet you are motivating me to keep on track. Fast day tomorrow but busy so should be fine.

midnights92 · 19/05/2026 19:19

Hey all - was on theast thread but stopped when I got pregnant, I was pretty much at my goal weight then. I'm about to pop in the next couple of weeks and am wondering if anyone has any experience with 5/2 post partum and breastfeeding.

IF has always been far, far easier for me because I can't be doing with meal prep or cutting out foods or super accurate calorie counting but I don't know how much of that will hold true when I'm off work. I'm not planning on doing anything for the first 8 weeks but my vague plan is to start a bit of 16:8 and maybe 5:2 depending on how we're all getting on at that point.

Keen to put some kind of plan in place as I'm 4st up and quite shocked at how quickly I flew past the recommended weight gain. I was not prepared!

mumofbun · 20/05/2026 14:29

@midnights92 I wouldn't be fasting when breastfeeding. I found i was ravenous and managed to lose weight anyway. Waiting past 8 weeks at least you'll hopefully see how you are/how the feeding is! Is this your first baby?

I'm doing a FD today, been ok so far! Even with a pilates class. Might attempt my first back to back as Friday I'm heading away!

MadMazie · 20/05/2026 22:39

@midnights92 I don't think it's a good idea at all while breastfeeding. It could impact your milk supply.

I'm planning to fast tomorrow, although my period came today and all I want to do is stuff my face with pizza.

HLBug · 20/05/2026 23:09

Hi @midnights92 if you have a look at the pinned post then 1000 cals is the recommendation for a fast day whilst breastfeeding (BF) but I agree with the others - don’t put any pressure on yourself, and see how you get on.

I also put on a ton of weight whilst pregnant so I know how you’re feeling. It’s amazing once baby is out and you’re going for pram walks, feeding, constantly changing and rocking how much comes off naturally. I think I started 5:2 about 6 weeks after birth, but the difference was I wasn’t breast feeding by then due to DD having an allergy which meant she was moved onto medicated formula. I actually found it easy because I was in the house alone during the day so could make only what I wanted to eat (which was pretty much the same thing every day because my brain was so fried) and any free time I had I was prioritising sleeping over eating!!

HLBug · 20/05/2026 23:10

@MadMazie I did indeed stuff my face with pizza today and am now regretting it, lying in bed with a sore bloated tummy. So use me as a warning!!

Mini for me tomorrow for sure.

Lucylurkery · 21/05/2026 05:34

Morning all, completed my fast day yesterday and was a good weigh in this morning thank goodness. A good lesson in not taking your eye off the ball for too long. Next fast day is Monday but I am going to try and eat much more healthier on my non fast days. I am trying to up my walking. I’ve just started reading the walking cure which has inspired me even more.
So glad to have this thread for the support and accountability.
Good luck everyone. I am up early for a bit of ‘forest bathing”😀

mumofbun · 21/05/2026 08:17

@MadMazie I'm due my period and fell into a doughnut last night 🙈 but I still ended on about 1000 cals and did a quite brutal pilates class so I'm pleased anyway.

Attempting a back to back although my husband isn't in board today so I'm not sure what will happen with dinner...it's my day off though so after school run I just have a rum, housework and a nap planned so should be ok during the day at least!

mumofbun · 21/05/2026 10:49

Omg run not rum

harriethoyle · 21/05/2026 10:59

Mmmmm. Rum 🤤

On for a mini today. Have swerved breakfast pastries at the course and waiting to see what lunch is…

OP posts:
MadMazie · 21/05/2026 15:30

It hasn't been too bad so far and even managed an intense gym class. I'm a bit peckish so will have a nectarine and some cottage cheese.

harriethoyle · 21/05/2026 16:13

I have resisted breakfast pastries (including my favourite vanilla crowns) and soft American cookies at my conference. Had protein only at lunch - grilled chicken and salmon skewers. I reckon I’ll end on about 800 after tea which I’m delighted by! Scales better reflect it tomorrow 🤣🤣

OP posts:
harriethoyle · 21/05/2026 18:45

Kitchen closing on 806 💪🏻

OP posts:
Lucylurkery · 21/05/2026 19:05

That’s impressive @harriethoyle especially if at a conference.

good day so far for me but am having a glass of wine!

MadMazie · 21/05/2026 19:16

I have had dinner (low cal ready meal from m&s) and still feel unsatisfied.
I am very much looking forward to eating smoked salmon and avocado tomorrow!

HLBug · 21/05/2026 20:33

Mini finishing on 845 over here. Have felt pretty yucky and bloated today - zizzi for tea last night did not agree with me! So today has felt fine and I’ve enjoyed the break

harriethoyle · 22/05/2026 07:57

Another lb off and only 4 to go to be back at my happy weight. Shame it’s BH weekend and I have my bff staying!! 🤣🙈 I ordered some friexinet 0% last night so I’ll revert to that on a couple of nights to limit my alcohol intake…

OP posts:
MadMazie · 22/05/2026 21:23

harriethoyle · 22/05/2026 07:57

Another lb off and only 4 to go to be back at my happy weight. Shame it’s BH weekend and I have my bff staying!! 🤣🙈 I ordered some friexinet 0% last night so I’ll revert to that on a couple of nights to limit my alcohol intake…

Enjoy it! Don't even think of calories. Time with bff is priceless.

HLBug · 25/05/2026 18:15

Ah it was all going so well….then the ice cream van came round as the kids were walking back from school. So, one mint feast later and I’ve ended on a Mini. Kitchen closing on 853. Back tomorrow for Day 2.

harriethoyle · 26/05/2026 11:50

I didn't think of calories or alcohol units @MadMazie and now I feel like I've been run over 😂 We've LOADS of left over food too so I am taking it easy today and will fast tomorrow and Thursday, with a mini on Friday. I've also said to DH I will drive to the birthday party we are going to on Saturday so taking it easy on the booze.

Has anyone else found as they've got older that their tolerance for alcohol has decreased? I almost felt poisoned yesterday night - I'd had maybe 4-5 glasses but with food, which a year ago I wouldn't even have blinked at but I was headachy, sick, had an upset tummy and terrible heartburn. I said to DH that it was absolutely not worth the pleasure that chilled rose brings! I have been actively cutting down recently so my tolerance as in drunkeness has definitely reduced but I was really shocked at the number of horrid side effects yesterday brought.

OP posts:
mumofbun · 26/05/2026 15:17

I also had a weekend of not thinking about everything! Weighed myself this morning which was obviously a horrible idea...telling myself it's all alcohol/period bloat! Back to gym class tonight and then FD tomorrow!

mumofbun · 26/05/2026 15:19

@harriethoyle I can still hold my drink pretty well but sometimes wish I couldn't then I wouldn't have so many 😅

I did wonder what sort of age everyone was. I'm not sure if I'm entering the stage of life where the weight will become harder to shift 😭 I'm not far off 40!

HLBug · 26/05/2026 18:43

The heartburn, oh the heartburn @harriethoyle that’s only been the last couple of years for me. Also the “hangxiety” when I dread reliving the stupid stuff I’ve said and done.

closing today on 758 and it’s been a tough one.

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