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Fast800 Misery

60 replies

CareerChange24 · 12/09/2025 18:40

I have been attempting the fast800 since Monday but I can’t get my calories lower than a 1000. I’m 5’3 and clueless how to get it off. How much would I lose on a 1000 in a month? I know people say it’s unhealthy but being 15stone is more unhealthy. Amy ideas for someone who knows how to gain weight. But not lose it.

OP posts:
Mrsttcno1 · 12/09/2025 18:54

The reason it’s unhealthy OP is that you cannot maintain it, so you could starve yourself to 1000 for a month and you might manage to lose a stone but the following month you’ll put that stone straight back on PLUS some more because the restriction will just make you binge. The only way to successfully lose weight & keep that weight off is to change your lifestyle, accept that it is a journey, eat less, move more, and you may not lose weight as quickly BUT you’ll lose more over 12 months consistently losing 1lb a week than you will if you keep doing crash diets and just losing, re-gaining and then re-losing the same 14lb for 12 months.

YetanotherNC25 · 12/09/2025 18:58

I tried the Fast800 and hated it. I was constantly hungry and didn’t have the energy to exercise. I know it works for some people but not for me.
Body coach was much more effective.
And now I log calories and exercise on my fitness pal and ensure I’m always in a calorie deficit.
If it’s making you miserable, stop. Find a different programme that you can follow and live your life. Otherwise it’ll be yet another yo-yo plan whilst you feel dreadful.

mediummumma · 12/09/2025 19:10

You’ll not be able to sustain 1000 calories a day, which will lead to less movement overall, low mood and an eventual binge. So save yourself the pain right now!

Do you know how many calories you were consuming each day to reach or maintain 15 stones? If not, start by tracking your ‘normal’ meals and snacks for a week or two. Then, once you have some data, decide what can be removed, what can be substituted for more filling or lower calorie alternatives and see where that then leaves you.

The idea for sustainable weight loss, without regain, is that the things you do to lose the weight must be maintained in order to sustain the weight loss. Eating at 1000 calories needs to be sustainable for life…is it?

Seriously, I understand that you are desperate but this approach you are using now will not work. You need to accept that there is only a longer-term answer for this long- term problem.

PoliteRaven · 12/09/2025 19:27

"How much would I lose on a 1000 in a month?"

It depends what your BMR and TDEE are. You can find online calculators to work it out. No idea how accurate they are.

I don't know exactly what calorie deficit I'm in, I'm just trying to consume somewhere around 1500 to 1800 a day, (using the calculators 1852 is supposed to be my 'maintenance calories, I'm also around the same height as you) occasionally I'm lower but honestly I'd be floored if I did less than 1500 every day. I was 9 stone 5 at the beginning of July and I'm now 9 stone and a bit. I'm v happy to do it slowly - I think it's the best way. FWIW us shorter people do find it harder to lose weight, ho hum. Can you do 7k to 10k steps a day to boost your metabolism?

Every pound of fat lost is a 3,500 calorie deficit if that helps.

I can understand your frustration but honestly it will be best to be patient.

SabrinaThwaite · 12/09/2025 19:38

You could try Fast 800 two days a week and aim for 1500 calories the other five days.

I did the 5:2 diet this way (could never get as low as 500 calories on a fast day) and lost two stone over 4 months (12st to 10st).

DareMe · 12/09/2025 19:39

I’ve just started this but am the opposite. I’ve had to eat slices of cheese to get to 800 some days.

SabrinaThwaite · 12/09/2025 19:43

Or even up to 1800/1900 calories on non fast days. That way on a fast day you know you can look forward to larger portions of (healthy) meals the next day.

DareMe · 12/09/2025 19:43

The whole point of fast800 is that it only lasts a few weeks then you move to 5:2 and then to maintenance once you hit your goal weight. You aren’t supposed to ‘sustain’ it indefinitely.

Wishiwasatailor · 12/09/2025 19:44

i did fast800 and you end up eating a lot of green veg, healthy proteins and fats. My partner would join me and would often not be able to finish the huge salads and meals. I would HIGHLY recommend the app over the books or just calculating it yourself.
the app gives you daily balanced meal plans and shopping lists. I found i spent significantly less on the weekly shop than I did previously and it was much much easier to stick to.

CareerChange24 · 12/09/2025 19:45

DareMe · 12/09/2025 19:39

I’ve just started this but am the opposite. I’ve had to eat slices of cheese to get to 800 some days.

Really? I wish that was me. If you eat so little you surely don’t need to lose weight. I need to shift it quicker than a pound a week due to my size. I can do a 1000 comfortably it’s the 800 that I’m struggling to get to. I guess I want someone to come along and say 1000 calories and I’ll still lose a stone a month. I know people say to do it slow or it will pile back on but I did do 1000 calories about ten years ago and it dropped off and didn’t regain it until the last two years due to depression and antidepressants. Literally gained four and a half stone in two years and that’s making me sooooo miserable. I can’t even look at myself in the mirror I’m so horrified.

OP posts:
Careeringallovertheplace · 12/09/2025 19:46

You'll just end up bingeing. Find another way. Mine was that I found exercise i enjoyed (home workouts) ans at the same time reduced evening snacking

DareMe · 12/09/2025 20:27

CareerChange24 · 12/09/2025 19:45

Really? I wish that was me. If you eat so little you surely don’t need to lose weight. I need to shift it quicker than a pound a week due to my size. I can do a 1000 comfortably it’s the 800 that I’m struggling to get to. I guess I want someone to come along and say 1000 calories and I’ll still lose a stone a month. I know people say to do it slow or it will pile back on but I did do 1000 calories about ten years ago and it dropped off and didn’t regain it until the last two years due to depression and antidepressants. Literally gained four and a half stone in two years and that’s making me sooooo miserable. I can’t even look at myself in the mirror I’m so horrified.

I am eating a lot of fish, vegetables and salad. Eggs sometimes, chicken. I don’t eat breakfast, never have. I have a coffee with couple of tablespoons of cream instead.
I am obese and just had a blood test that shows my blood glucose is high, hence why I have started this.
Before this my diet wasn’t terrible but I was eating big portions of carbs, wholemeal, but still too much and crisps/pizza probably too much too and wasn’t doing any exercise. The blood test has given me a kick up the arse really. I am really annoyed at myself.

Wednesdayonline · 12/09/2025 21:21

If you eat 800/1000 calories a day for an extended period, your body will go into starvation, and it'll try it's very best to cling onto fat to keep you alive. That's very stressful for your body as well which isn't healthy. Calculate the calories needed to maintain your weight (calculators online), then deduct 500 calories from this, increase your exercise (even just walking an extra 30 mins per day) and you'll lose a stone in a few months. Consistency is always key with weight loss.

NuovaPilbeam · 12/09/2025 21:24

Losing a stone a month you just fuck your metabolism and lose muscle. Its never sustainable (unless you really are huge to begin with) however you try and do it

Itstheshowgirl · 12/09/2025 21:29

OP get something like MyFitnessPal (or similar there are loads to choose from) and get an idea of the calories you should be aiming for to lose weight steadily. You cannot sustain 1000 calories a day.

OxfordInkling · 12/09/2025 21:34

I did a month. Lost a stone. Haven’t put the weight back on. Key for me was massive salads, plus protein and minimal carbs. Crustless quiche for lunch (with massive salad). Granola and yogurt for breakfast (small portion of granola). Meat and more veg for tea.

Overrunwithlego · 12/09/2025 22:07

I did the Fast 800 5 years ago, for 10 weeks, and lost about 2.5 stone / 16kg. I wouldn’t worry too much about it being slightly more - you will still loose weight. Don’t do it for more than 12 weeks. Whilst is it perfectly manageable, the really important thing is where those calories come from. Wholefoods, protein and fats and what you need. If you are eating processed, carbs, sugars etc, then it will be very difficult to stick to that calorie level, and you will then most likely binge.

In the last year I have noticed I was starting to put a little bit of weight back on - not loads (a little under a stone), but enough for me to notice. And I knew it was because I was falling slowly back into old habits - snacking, biscuits late at night, having ‘treat’ meals regularly. I am now doing another quick bout of the 800 (or more like 1000). Partly to lose that stone, but more importantly to get me back in the right habits. I find its enough to reset my eating so I stop craving those types of foods that will lead me to put the weight back on. So for me, the 800 WAS the way to change my lifestyle.

I can’t guarantee it will work the same for you, but it’s definitely been the easiest and most long lasting weight management approach I have found. It has not fucked up my metabolism (quite the opposite) and it has not led to muscle loss. However it is really important though that you maintain your muscle - I do 3 weight based training sessions a week.

TartanBarmy · 12/09/2025 22:12

Don’t be horrified - you’re just you. Nothing horrifying about your own self. Fluctuations happen.

Protein and green veg is filling. White fish and prawns and things like that are low calorie and filling. Skipping breakfast helps me - once I wake my appetite up I feel like eating all day.

I also like a jacket potato in the evening weighed for calories - then just butter, salt and pepper. Butter also weighed. But it’s not likely to be more than 350 cals in total and it’s hot, delicious east comfort food that is filling but not meat or fish.

Glitchymn1 · 12/09/2025 22:21

I did 1,000 and intermittent fasting, works for me. Vegan so eat lentils/chickpeas, veg, 1 slice sourdough After a month I had the odd cheat day (wine). It was hard the first two weeks, then I fasted longer 27 hours plus and felt great. Ate clean, loads of water. Wall Pilates, planks and squats just a few mins a few times a day.
I do have a dog though, so have to take the dog out no matter how I feel.

Skin never better, stomach getting flatter, clothes fitting well.

Hibernatingtilspring · 12/09/2025 22:29

Losing a stone a month isn't a good thing for the vast majority of people. Your body has a natural limit on how much fat you can lose. If you do lose a stone a month, the likelihood is that will include a fair proportion of muscle mass, doing so will make you weaker, might leave you with an overall shape you didn't want, and it will mean that your body will regain more fat once you start eating 'normally'.
Crash diets don't work for long term weight loss. If they did, we wouldn't have so many people constantly trying them!

Wonderwendy · 12/09/2025 22:38

I absolutely CANT calorie count. I just can't do it, it leaves me thinking about food all the time. So what I've started doing is a 36 hour fast once a week. So I eat dinner, then don't eat at all the next day then start from breakfast the day after that and just eat the same as I always do on the days I'm eating. It just makes it so much easier for me. But I'm an all or nothing sort of person. Would that maybe be better?
Apparently it's what Rishi Sunak does too. Now I'm no Rishi fan but you have to admit the man is slim!

DareMe · 12/09/2025 22:41

Some need to read the science and evidence base behind the fast800. So much incorrect information in a lot of these posts.

5128gap · 12/09/2025 22:53

My advice is to stop with the ridiculously low unsustainable calories, which will mess up your metabolism and won't give your body the nutrition it needs (leading to all sorts of nasties from low immunity to muscle wastage) and walk walk and walk again. Aim for 15-20k steps a day, proper walking, but also jogging or walking in place in front of the TV counts, and eat 12-15k calories a day, and you should see weight loss.

bosch · 13/09/2025 17:59

I've been doing a version of fast 800 based on a couple of the recipe books by claire bailey and mimi spencer. I'm not doing it perfectly - holidays and birthdays have got in the way - but I've lost 6kg over 3 months. I know you're not supposed to do fast 800 for more than 12 weeks but since I've had breaks, and I feel well, I'm going to carry on. Tell us what a typical day's meals look like for you?

RosyDaysAhead · 13/09/2025 18:03

Much healthier to do the maths! Work out what you basal metabolic rate is for your height/weight and then use the online calculators to work out the amount of calories needed to lose weight. Then work out how many’s calories half of that figure is - that’s how much protein you need to eat, the remaining half is split equally carbs and fats (dairy/olive oils/avocados etc). Add in a small amount of f
daiuy exercise - a walk around the block a swim etc and gradually increase it as you feel
comfortable. I’m 5’1 and weight 15.5St and I eat around 1500 calories a day. I was 18 stones but have lost weight doing this. I joined a gym in April and it’s coming off a little faster now. The protein goal is important as this is what makes you feel full!