Calories for weight loss - how low is too low?

[poundshoptealights]

I am so confused about weight loss diets. I need to lose about three stone and want to get at least some of it off quickly. I gained it last year when I had one Covid and it's really impacting my confidence.

Long Covid was scary and I have worked hard to get back to good health. I now do weightlifting 3 x a week and park run every weekend. My BMI is 26.5, so not too bad, but losing 3 stone would put me at my optimal weight (I am tall but don't have a heavy frame, so lower end of BMI is best for me).

My question is how many calories I can cut to for fast weight loss, without getting tired or obsessed with food? I keep reading about the Fast 800 but it seems very low calorie for someone my height (5'11'). I also want energy for exercise and want to add more running into my routine. I don't know if the Fast 800 can support this.

That would be ridiculously low for you. Forget about getting weight off quickly. Work out your tdee and reduce your maintenance calories by 20% to get a calorie weight loss target. I lost my 3.5 stone by mostly sticking to 1,500 cals per day. I’m 5ft 10. I’ve kept it off 3 years by sticking to my maintenance cals. Crash diets don’t work because they are unsustainable.
tdeecalculator.net

Here, a Dr talking about the 800 diet

vm.tiktok.com/ZMY97mfnB/

No less than your BMR, probably 1400-1500 for your height and weight

I am much shorter than you 5ft 3. I lost 3stone in about 6 months on 1400 per day, I have maintained for a year so far, I am still probably a little heavier than you are aiming for (certainly relative to my height), I think very low calorie diets are dangerous short term, unless you live a very quiet existance and long term via metabolism impact.

After my last pregnancy i had a bmi of 25.8 and i went on a diet. I did 1200 calories and tbh i was hungry all the time at first. After a while i figured out which low calorie foods are more filling etc. but it was a lot of trial and error til then and i suffered a lot.
It was worth it though, because im slimmer than before kids now and ive never felt better.

Work out your TDEE and deduct 750. Don't go below that.

I was advised by a PT never to go below 1400, and i'm only 5 foot 5. You want to be careful not to lose the muscle you have been putting on lifting.

(I'm not into bodybuilding at all, but its clear to me that they are the real experts at fatloss with muscle retention, so I read/watch a lot of content by bodybuilders. Have a look at some body building weightloss vidoes (they often called 'cutting' or 'a cut') on YouTube.

Thanks everyone, I am now convinced that the Fast 800 is a bad thing.

My gym has a body composition monitor so I know that my BMR is approx. 1800 kcal a day. I just used the TDEE calculator and it gives me 2600 kcal for maintenance and 2100 kcal to lose 1lb a week. Can I drop it to 1600 kcal and lose 2lbs a week, or will that start to have negative effects?

One other thing - I entered my activity level as moderate (3-5 gym sessions a week). But I am pretty sedentary apart from the gym because I wfh with very little walking or incidental exercise. Would you still call my activity level moderate, or maybe light?

Thanks @RelentlessForwardProgress. I don't look muscular but have definitely built major strength since Covid, when I could barely walk ten minutes down the road for months! I am so proud of my strength and energy now and definitely want to protect it.

I'd put your activity level as light rather than moderate. You can reduce your TDEE by 1000 but you may find yourself really hungry.

Thanks @MaireadMcSweeney light activity puts my TDEE at 2350 kcal per day to maintain. 1350 kcal starts to sound a bit too low so I guess maybe 2 lbs a week isn't achievable.

It's weird. I have a sister who has recently lost a lot of weight on a meal replacement diet. She had a lot to lose tbf (I am guessing 6-7 stone) but has managed it and seems very happy and has lots of energy. I don't think I could live on that and stay sane. She is much shorter than me but I don't know how relevant that is.

www.bodybuilding.com/fun/calrmr.htm
Do some research on your macros and Resting metabolic rate. Link above has loads of info and different calculators to plan your meals and have a better understanding of what calorie intake you need to have for weight loss. protein is sooo important for building muscle- building muscle burns more calories!

@Notallislost thank you!