Myfitnesspal told me I should be having 1640 cals a day. According to another site though, I shouldn't have less than my BMR a day which is 2359. There's no way on earth I'd lose weight eating that many calories a day.

How tall are you? How much do you weigh? I would figure out the TDEE of what you want to weigh, and compare it to MFP's recommendation. You of course have to take in less than you need, otherwise weight loss isn't realistic. I don't think 1640 is too low, so long as you get your nutrients in with that. I have been eating around 1600-2000, and I am sort of hovering, not really losing, because I took a small break. Depending on how tall you are and how much you need to lose, you may be fine with less than what MFP recommends. Sorry I don't have more to offer, but I definitely think 1640 is going to be fine, unless you are 8 feet tall.

I'm 5ft 5 and weigh 340lbs.My tdee is 2830 if sedentary and 3243 if slightly active.There's no way I can eat 3000 and not gain weight and even my BMR is too much I feel.The tdee of what I want to weigh is 1874.
I don't actually ever eat my entire calorie allowance as it is-I always have between 70 and 200 left over.I'm trying to avoid chocolate and junk food as they start me off on binges,but fruit and veg fill me up so that I don't want to eat more.

My BMR is 2132 and I aim for 1200-1300 calories a day. I know everyone is different and I've 2 inches on you in height, but I agree with Brandis that 1640 should be fine.

I would at least push what you are erasing up to 1874. Its a trap to eat too little even if you are full. Just add some more calorie rich foods into your daily menus.

It should be easy. You can still do it and easily avoid junk food and chocolate.

eat full fat dairy, some cheese, nuts and seeds and more good oils.

I was stuck for over a month with no weight loss at around 1400-1600, and pretty intense exercise levels. It's when I added back a few hundred calories that I finally lost a few pounds. I had a hard time doing that, because I wasn't hungry, due to me eating a lot of bulky foods. I put more fat in in the form of nuts and more oils/fats when cooking. I think if you feel fine at 1600, and you aren't hungry, you would do alright to just keep it there.

I think pattience feels that if you deprive yourself by too much, it will backfire. I think that could ring true for some who make too many severe changes. If you are comfortable at that level, stick it out for awhile, and if you need to, go back up. You may ultimately end back up where you are now though as you get smaller. I think I was just a little too low for my height and intensity of exercise. Ultimately, do what works and is healthy and sustainable long term. Best of luck!

I don't do a lot of exercise as yet-I'm only walking really and that's an hour maximum at a slow pace.I did some dancing yesterday for 17 mins-couldn't manage any more.Oh and I do ballet-the really basic stuff at the barre and some stretches-that's it.
I don't feel deprived as yet-I was 200 under yesterday and that was after having some jelly(jello for you Americans ) and yogurt as a snack.If anyone wants to have a look at my food diary on mfp you're quite welcome.
For breakfast today I have had 30g cereal,20mls of milk,a small banana, a red pear and a satsuma,plus a black coffee with sweetener.And I can happily say I'm not hungry.
Of course I won't know if I'm doing OK till Wednesday morning when I weigh in....

Yes i mean it will backfire. Maybe you will go along fine for some months but your metabolism will be slowing down and there will be effects that will cause you to put the weight back on. But you probably won't last that long.

Wow-well thanks for that total lack of support right there.I probably won't last that long?? How would you know how long I'll last? What makes you an expert on how many calories I need and how my body reacts to food? I can tell you right now if I was eating my current tdee I would be gaining weight.When I calorie counted previously I was on 1500 calories and was on that quite happily for 5 months until I got pregnant.I lost 35lbs in that time looking at my old records.If I was eating even my BMR I would not lose anything at all.
You actually sound like my Mum-all I ever hear from her is how I won't manage to stick to my diet,how I won't last long enough to ever be slim...this is not what I expected from a support site! I'm not starving myself-I'm eating what mfp thinks I should be eating!

The target that MyFitnessPal gives you is for net calories, not for total number of calories consumed. The idea is that you exercise an additional amount to get down to the final net calories.
Example: My current net calories goal is about 1650, but I ate 2100 calories and exercised away about 650. I still ended up with a negative net calorie amount according to MyFitnessPal, even though I went over my goal of 2000 calories.

Hi PPR71,
Just guessing here, 1640 sounds a little low. There's a lot of guesswork and tweaking to figure out what works physiologically and what can be sustained without white knuckling it. If you feel fine on 1640, go for it. If it starts to feel too restricted, loosen up to 1874, or even try alternating those amounts (loads of fun on mfp, lol!)

There seems to be a sweet range where you burn fat the most efficiently. If you are under it, your weight loss can stall, just like if you go over it, though for different reasons. The diet plan I used prescribed an extra ~200-250 calories for folks over 300 lbs. Then it dropped to ~120 extra for those over 200 lbs.

Exercise can speed up your metabolism and help the weight loss. Depending on the intensity, you may need more calories for that too, to avoid a stall.

The scale can provide feedback, but I'd mostly pay attention to the monthly trend, since the daily & even weekly fluctuations can be an emotional roller coaster--(been there done that, still do it!) And to get yourself through those inevitable disappointing weigh-ins, I'd suggest getting 1 or 2 baseline measurements, like thigh and waist circumference. Those will shrink even when the scale is reflecting water retention, big C, TOM, etc. Be sure to measure in the same anatomical locations each time.

Enjoy the journey--we're with you!

I don't understand that at all...I have my walking synced through endomondo to mfp and it ADDS exercise calories -so today I had 1640 at the beginning of the day, did exercise and it added 558 to that total...so far I have had 1399 and still have 799 left because it's added the exercise on.I won't eat those though-I have 241 left without counting exercise and that's what I have left to eat today.

mars735-thanks-I plan to keep an eye on the scale and adjust calories if I need to.I do have a very slow metabolism though due to thyroid issues so really feel that I can't eat as much as my BMR would suggest as I just won't lose anything. My exercise is very low intensity right now-I've had plantar fascitis since last October and did pretty much nothing since then due to pain, so all I am doing now is gentle walking.If I ever get to the point where I can jog I will adjust calories then.
I used to be a daily weigher but that led to eating way too much so I'm going to stick to once a week when I get my printout on the machine

You eat as you feel. If at some point you feel you are getting hungry, add some nutritious, filling foods that you love - peanut butter, avocado, etc.

Nothing says you have to eat the same all the time. Oftentimes in the beginning it's easier to eat less. Later, if you need a to eat a bit more, sure the weight loss will slow, but it will still be headed in the right direction as long as you are burning more than you are consuming. Being flexible to allow for long term wight loss is the key.

As far as metabolism slowing down, it will no matter if you lose weight slowly or quickly. it figure out that you are eating less than you ar consuming. But, it will recover once you get into maintenance, but probably not as quick of a metabolism as a person who never was overweight. Totally unfair, I know.

Ooh avocado...I do like avocado I'm trying to stay away from the junk food and chocolate as it WILL make me give up the diet. I think you're right in that it's easier at the beginning to eat less as it's all new and exciting.Once boredom sets in I have some ideas how to shake it up a bit I'm taking advantage of all the lovely fruit and veg available at the moment
And yes totally not fair about the metabolism LOL