What is a calorie deficit?
A calorie deficit just means you are eating less than your body burns in a day. Your body covers the gap by tapping into stored fat, and that is how you lose weight. There is no magic to it and no special food that creates one. Every diet that has ever worked, from keto to intermittent fasting to plain old portion control, works because it puts you in a deficit. This calculator finds yours by estimating your maintenance calories first, then subtracting the right amount based on how fast you want to lose.
How big should your deficit be?
For most women I coach, a deficit of 250 to 500 calories a day is the sweet spot. That is roughly half a pound to a pound of fat loss per week. It is fast enough to keep you motivated and slow enough that you hold onto your muscle, your energy, and your sanity. The math is simple: one pound of fat is about 3,500 calories, so a 500 calorie daily deficit adds up to a pound a week.
A 750 calorie deficit, around 1.5 pounds a week, is the most I will ever suggest, and only for women with more body fat to lose. Going harder than that almost always backfires. You lose muscle along with fat, your workouts tank, your hunger goes through the roof, and you end up bingeing your way out of the deficit entirely. Slow and boring wins this game every time.
Why women stall in a deficit
This is the single most common message I get: "Ryan, I am in a deficit and the scale will not move." Nine times out of ten it is not a broken metabolism. It is untracked food creeping in, an old maintenance number that dropped as you lost weight, water retention hiding real fat loss, or years of chronic under-eating that put your body into protection mode. The fix is rarely "eat even less."
I wrote a full breakdown of every reason this happens, and exactly how to troubleshoot it, in my guide on being in a calorie deficit but not losing weight. If your number looks right but the scale is stuck, start there. You can also run your full macros, not just calories, with my macro calculator for women.
Frequently asked questions
What is a calorie deficit?
A calorie deficit means you are eating fewer calories than your body burns in a day. Your body makes up the difference by pulling from stored fat, which is how you lose weight. You find your deficit by starting with your maintenance calories (your TDEE) and subtracting a set amount, usually 250 to 750 calories per day depending on how fast you want to lose.
How big should my calorie deficit be?
For most women, a deficit of 250 to 500 calories per day is the sweet spot. That works out to about half a pound to one pound of fat loss per week, which is steady, sustainable, and protects your muscle and energy. A 750 calorie deficit (about 1.5 pounds a week) is the most I would ever recommend, and only for women with more weight to lose. Bigger is not better. Aggressive deficits backfire with muscle loss, low energy, and hormone disruption.
What is the lowest calories a woman should eat?
I do not take women below 1,200 calories per day, full stop. Eating less than that for any real length of time tends to crash your energy, disrupt your cycle and hormones, slow your metabolism, and eat into your muscle. If a calculator tells you to eat under 1,200 to hit an aggressive rate, that is your sign the rate is too fast for you. Pick a gentler pace and you will still lose fat without under-fuelling.
Why am I in a deficit but not losing weight?
Usually it is one of a few things: you are eating more than you think (untracked bites, oils, and weekends add up fast), your old maintenance number changed as you lost weight, water retention is masking real fat loss on the scale, or you have been under-eating for so long that your body is in protection mode. It is almost never a broken metabolism. I break down every reason in my full guide on being in a calorie deficit but not losing weight.
Are these numbers exact?
They are an accurate starting point, not a permanent prescription. Calorie equations estimate within a reasonable range, so track your weight, measurements, and energy for 2 to 3 weeks and adjust from there. Your real-world results always beat any formula.
Want a plan built around your deficit?
A calculator gives you a starting point. Coaching gives you a custom plan that adjusts every week based on your real progress, so you actually keep losing instead of stalling out. That is what The Recomp Method is built for.
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