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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!!

363 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:
harriethoyle · 10/08/2026 08:58

Anyone with me today? Day 1 of a b2b…

OP posts:
mumofbun · 10/08/2026 10:10

I'm in today, already a struggle though as i'm so hungry...

harriethoyle · 10/08/2026 13:47

Same @mumofbun I had to steal a (mini) pack of biscuits from the work kitchen for an 11am hit😂I slept appallingly last night and it's really not helping...

OP posts:
mumofbun · 10/08/2026 15:32

harriethoyle · 10/08/2026 13:47

Same @mumofbun I had to steal a (mini) pack of biscuits from the work kitchen for an 11am hit😂I slept appallingly last night and it's really not helping...

I went to the vending machine for a boost 😂

harriethoyle · 10/08/2026 18:28

Kitchen closing on 774. How did you get on @mumofbun ? x

OP posts:
mumofbun · 10/08/2026 20:58

harriethoyle · 10/08/2026 18:28

Kitchen closing on 774. How did you get on @mumofbun ? x

It all went to pot as we hadn't planned dinner and ended up being invited for a roast ... Try again tomorrow! I did speed walk across town for Pilates though!

harriethoyle · 11/08/2026 07:51

I love a roast @mumofbun - totally irresistible! The IF will have helped, no doubt.

Im back for day 2 of 2… wish me luck!

OP posts:
harriethoyle · 11/08/2026 18:30

Kitchen closing on 924 - higher than intended but I felt positively weak at 10.45! So a colleague gave me his biscuits 🤣

Going to Dishoom for a curry tomorrow night so definitely back on Thursday for day 3..!!

OP posts:
harriethoyle · 13/08/2026 10:06

Signing in for day 3 after a positively gluttonous night out last night... BUT IT WAS SO GOOD 😂

OP posts:
harriethoyle · 13/08/2026 20:48

Kitchen closing on 689 😊

OP posts:
midnights92 · 16/08/2026 23:45

Back at it tomorrow for the first time in about a year of pregnancy and newborn stage to lose about 3st of the 4st I gained while pregnant. I'm EBF so going to be doing 2 x minis per week instead of proper FDs and see how it goes. Never really stopped doing 16:8 because it had just become a habit, so hopefully that will make the transition easier.

Hope everyone is doing well!

harriethoyle · 17/08/2026 07:25

Welcome back @midnights92 !

Im fasting today then on holiday with friends until next Monday so only one day this week. Will try and keep the activity levels up to compensate!

OP posts:
HLBug · 17/08/2026 19:07

Kids are back to school - whoop whoop!!
BUT I have a shocking week at work and an interview on Thursday for another role…. so I’m stressed 😩 and when I’m stressed I EAT.
I’m being kind to myself and aiming for 2 or maybe 3 minis this week. Kitchen closing today at around 1087

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