Calorie deficit for women
Most women have a maintenance somewhere between 1,800 and 2,200 kcal, which makes a sensible deficit 300–500 kcal a day and leaves intake around 1,500–1,800 kcal. That is roughly 0.3–0.5 kg (0.7–1 lb) a week.
Nothing about the arithmetic is female-specific. What is specific is the starting number — and because maintenance is lower on average, mostly a function of body size and lean mass, advice written in absolute calories hits harder.
The same 500 kcal is not the same deficit
Generic advice is almost always phrased as “cut 500 calories”. What that single instruction does to four people:
| Maintenance | A 500 kcal cut is | Leaves you eating |
|---|---|---|
| 1,700 kcal | 29% below | 1,200 kcal |
| 1,900 kcal | 26% below | 1,400 kcal |
| 2,100 kcal | 24% below | 1,600 kcal |
| 2,800 kcal | 18% below | 2,300 kcal |
The bottom row is a comfortable diet. The top row is a different intervention wearing the same label. Percentages travel; absolute numbers do not.
So work in percentages. The reasoning behind the 15–25% range applies unchanged — on a 1,900 kcal maintenance, 20% is 380 kcal, not 600. Get your own number first, by estimating it or better by measuring it: a 200 kcal error at the start is a 10% error in everything after.
Why so many plans land under 1,200
1,200 kcal is widely treated as the floor below which a diet is hard to make nutritionally adequate. It turns up constantly as a target instead, and the reason is pure arithmetic: a woman with a 1,700 kcal maintenance who wants the standard 1 lb (0.45 kg) a week subtracts 500 and lands on 1,200 exactly. Ask for 2 lb (0.9 kg) and the same sum returns 700 kcal.
If your arithmetic lands under about 1,200, change the timeline rather than the plate. Iron, calcium, fibre and adequate protein become difficult to fit at once, and very large deficits also shrink themselves — hunger rises, incidental movement falls, and the gap you get is smaller than the one you planned. More on what overshooting feels like.
Your cycle can hide a fortnight of fat loss
In the second half of the cycle, fluid retention of 0.5–2 kg (1–4 lb) is ordinary. It builds through the luteal phase and clears within a day or two of your period starting — which is why the scale sometimes drops 1.5 kg (3 lb) overnight for no reason you can identify.
Put that next to the signal. At a 400 kcal deficit you lose about 0.35 kg (0.8 lb) a week, so a fortnight of real progress is roughly 0.7 kg (1.6 lb) — comfortably inside the noise. The scale can sit flat, or rise, for ten days while fat loss continues throughout.
The fix is to compare like with like: this cycle’s week one against last cycle’s week one, using weekly averages rather than single mornings. Read that way a month of data is legible; read day to day it is not. Appetite also rises modestly in the luteal phase, which is real rather than weakness — plan a slightly higher intake for those days and take it back later in the month. Running the deficit as an accumulating total rather than a daily pass-or-fail helps here, which is what Caldown does. If you are not cycling, the other reasons a scale stalls still apply.
Two things not to crowd out
Iron. Premenopausal women need roughly 15–18 mg a day depending on the guideline, against about 8–9 mg for men, because menstrual losses have to be replaced. Iron-dense items — red meat, lentils, fortified cereal — are often the first casualties when “eating lighter” collapses into salad, and low iron is then almost indistinguishable from an oversized deficit: tired, cold, flat, breathless on the stairs. Pair plant sources with something containing vitamin C, and keep tea and coffee away from iron-rich meals. Do not supplement on a hunch — ask for a blood test, as too much iron is not harmless either.
Calcium, 700 mg a day under UK guidance and 1,000 mg under US, matters more than it sounds if you expect to diet on and off for decades. Dairy, fortified alternatives and tinned fish with the bones in cover it.
Protein is the third, and the tightest. The usual 1.6–2.2 g per kg is 105–145 g a day for a 65 kg (143 lb) woman — a third of a 1,500 kcal intake before anything else is on the plate — and hitting it is what decides how much of the loss is fat rather than muscle, especially alongside resistance training.
If your period stops, that is the signal
Losing your period while dieting is not a sign that it is working. It indicates energy availability has dropped too low, it happens at entirely ordinary body weights — especially when hard training sits on top of restriction — and the consequences for bone density and fertility are not trivial. The response is to raise intake back to maintenance and see a doctor, not to shave off another 100 kcal. The same goes for hair shedding, or for feeling cold all day rather than only in the evening.
Otherwise this is ordinary deficit management: work in percentages, recheck maintenance every 4.5 kg (10 lb), and read the scale in weeks. More on running a deficit.
General information, not medical advice.