Weight may have a part to play yes. Obviously for the excessively overweight, if they were eating around 4,000 a day, then downscaling too much, might cause an issue, so gradual downscaling could be preferable.
Recent studies indicate that not only can drastic caloric cuts, seem to promote Cortisol production, causing some Fat gain and being mildly counterproductive, but also this effect can be heightened if the person is stressing a bit about counting calories, which is why calories can be counted, but in ballpark terms, not to the point where someone counts things like Cornflakes and grains of Rice with tweezers, to get the right amount each time.
However if a sedentary female needs 1,800 on average, then they shouldn't undereat. Someone who exercises in normal Gym based terms, needs extra to account for that, but the person who maybe overweight and still overdoes it, may have problems, cutting down to some extent, so may need to gradually work down, but people who are undereating, to the point where they're not even getting within 30% of a sedentary average, risk very stunted progress and those closer to that target, can reduce the potential for fat release / burn problems, but still need to realistically
A: fuel the body adequately per day.
B: have a bit of surplus to allow for better Fat sacrifice.
It's not about crazy crash diet amounts, where you lose 6lbs a week, or 10lbs a week etc etc. It's not about people telling you you can lose "x" amount of stomach Fat a week, using 1,2 or 3 crazy old rules. It's about giving yourself enough to have what the body considers desirable, plus a bit extra, to help it to go above and beyond it's normal base levels of daily activity. I.E. going shopping, going up / down stairs, going to the toilet etc, in a way that's healthy and shouldn't result in the body utilising things it's not meant to use, to fulfill the purpose some of the calories you need should be doing instead.
Realistically, a female might be able to lose weight long-term, having 1,400 a day without exercising, but then you lose all the benefits of exercise, particularly any strengthening benefits, plus you don't guarantee that you're in a position to lose mostly healthy weight and not too much other stuff like msucle, Bone density and water, even if you can have sustained long-term weight loss, from around 1,400 calories a day without exercise included.
Even things like BMR's, (Basal Metabolic Rates), exist to tell you that is the bare minimum you need per day, for long-term metabolic health, as that's deemed effectively, the lowest amount you can regularly get away with at most, but a BMR reading is certainly not a target to aim for, by any means.
A bit like needing 10mg a day of Vit C to avoid Scurvey. That's not a target ot aim for at all. In men Vit C is a 90mg RDA, for women a 75mg RDA, but those figures aren't even enough to realistically get good immune system boosting, other immune factors like dietary Zinc aside, but if people started increasing the RDA's to anywhere between 500mg's to 1g, you'd need people to realistically supplement, when it's not always affordable and may induce fear, if some learn their imtake was just about scratching the surface, without being near to what was then deemed a better level to aim for. So in that instance a lower than preferable amount is deemed acceptable for now with something like that.
However a female having a diet around 1,200-1,400 a day, cannot guarantee good levels of Micronutrients and the necessary health benefits they provide and minor dificiencies in one or more Micros, may upset someones ability to become healthier, even if weight loss potential was largely unaffected.
if for example, someone got inadequate amounts of anything, directly or indirectly responsible for Bone health, like Vitamin C, Copper, Magnesium, Calcium, Vitamin D, Vitamin K2, Phosophorus, Boron and possibly Manganese and Silicon, then depnding on which og htose or how many, and the ingested daily amounts, it could only be a matter of time, before bones that started to thin and if they developed Osteopenia, (thinning Bones), they could one day fail to tolerate a slight Ankle slip when running, or a simple weightlifting exercise and fracture to some degree.
It is not too hard for people to achieve something like 2,100 calories a day, even a female. Yes it seems daunting, but don't forget a lot of overweight people, consume 3,000, 4,000 even more still with relative ease. Most of them are only consuming most of that from very bad things like Saturates, and bad Sugars like refined ones, as even heavy Salt is not contributary at all.
So this process is easily altered, by not having the refined Sugars, and reducing some of the saturates, then replacing most of the rest, (you are allowed some, around 20g a day, based on the 2,000 calorie intake), with unsaturates.
So although it seems hard at first, to get to grips with caloric intake figures of just over 2,000 a day for a female, it makes good sense, especially with increased activity and is not too difficult really, with a little good planning and choices

.