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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:
MadMazie · 26/05/2026 20:03

I'm also fasting today after the execceses of the bank holiday. I will do my second one on Thursday.

I think the heat has made it easier today.

Alcohol definitely makes me feel worse now I'm in my 40s.

harriethoyle · 26/05/2026 21:11

I'm not sure I dare to get on the scales tomorrow @mumofbun..!! FD day 1 tomorrow and gym after work. Same Thursday and then a mini-ish on Friday although my uncle is staying so won't be sticking to any strict limits.

Heartburn also a new thing for me @HLBug - my late DM suffered from it terribly but I thought I had escaped it. Not according to the agony a single cup of tea caused me last night!

OP posts:
harriethoyle · 26/05/2026 21:13

It's such a shame. Now I'm at the stage of life I can afford decent booze after a youth spent on snakebite and black, I can't take it any more!! I want to be able to quaff champagne with abandon, goddamit!

OP posts:
harriethoyle · 27/05/2026 11:01

Signing in for day one of two. Feeling hungry but strong!

OP posts:
harriethoyle · 27/05/2026 19:31

Kitchen closing on c.640. Haven't got my MFP app to hand but it was a typical thin sandwich fishcake FD. Did a spin class too! Back tomorrow for day 2..

OP posts:
HLBug · 27/05/2026 20:30

Well done @harriethoyle - smashed it! I’ve just put new batteries in the scales - what do we think the chances of me weighing half a stone less in the morning are 😅

MadMazie · 28/05/2026 16:16

I'm doing my second fast day today and I'm feeling pretty hungry. I'm trying to distract myself and fill up on herbal tea but it's not working.
I generally find the second day harder but I tell myself it's because that's when I really dip into a deficit for the week.

harriethoyle · 28/05/2026 17:20

I’m also fasting @MadMazie amd I’m also finding it hard!

I’ve cancelled tonight’s gym class, too hot and instead I’m going to spinning tomorrow after work. A good way to put off drinking until 7pm!

OP posts:
MadMazie · 29/05/2026 10:27

Just had my weigh in and I've lost 5 pounds now. Not bad for 3 weeks!

harriethoyle · 29/05/2026 11:44

That's epic @MadMazie and a great reminder of the importance of consistency!

OP posts:
mumofbun · 30/05/2026 07:10

I've not been very good with fasting. Need to get back to it! Gym classes are on the up though!

But the good news is the weight gain was just post weekend/period bloat and I'm edging closer to half a stone off. And I did my measurements and I'm -1 inch off my waist!

MadMazie · 01/06/2026 14:35

I'm fasting today. No calories eaten so far and I did a circuit training class.

HLBug · 01/06/2026 19:08

Finishing on 687 today. I’m just back from a girly weekend away so I needed this fast! Feeling much better now. Back for Day 2 tomorrow

harriethoyle · 01/06/2026 19:16

Well done both! I’m on holiday so all bets are off and I’ll be back moaning about my weight gain next Wednesday 🤣🤣

OP posts:
MadMazie · 01/06/2026 19:49

Have a lovely time @harriethoyle

harriethoyle · 01/06/2026 19:55

Flying out tomorrow @MadMazie but the night before shears counts as the start of hols doesn’t it?!

am taking my gym kit and am going to sign up to some morning fitness classes. Not too early though. I want some lie ins!

OP posts:
HLBug · Yesterday 10:58

Non-Scale Victory (NSV) for me today - went into Hobbs and came out with a Size 10 linen suit set. Whoop!

HLBug · Yesterday 21:02

Day 2 of B2B finishing on 677. Had a good day today Smile

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