"Eat less, move more" is technically correct and practically useless. The number that actually matters is your daily calorie target — and most people are guessing at it, often by a margin wide enough to explain why the scale won't move.
Start with maintenance, not a diet number
Before you can eat in a deficit, you need to know what "even" looks like — the number of calories that keeps your weight stable. This is your Total Daily Energy Expenditure (TDEE): your body's baseline burn (BMR) plus everything you do on top of it — walking, workouts, fidgeting, digestion.
A common starting formula for BMR is Mifflin-St Jeor:
- Men: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
- Women: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
Multiply that BMR by an activity factor — roughly 1.2 for sedentary, 1.375 for light activity a few days a week, up to 1.55 or higher for regular training — and you get a workable TDEE estimate. It won't be exact. Nobody's is. It's a starting point you correct using real data, which is the part most people skip.
The deficit size that actually sticks
One pound of body fat is roughly 3,500 calories. That math tempts people into aggressive deficits — cut 1,000 calories a day, lose two pounds a week. In practice, deficits that large are hard to sustain, tend to cost more muscle than fat, and usually end in a binge that erases the week's progress.
That pace works out to roughly 0.5–1 lb (0.25–0.45 kg) of weight loss per week for most people — slow enough to preserve muscle and energy levels, fast enough to stay motivating.
| Goal | Daily deficit | Approx. weekly loss |
|---|---|---|
| Conservative, sustainable | 250 kcal | ~0.25 kg / 0.5 lb |
| Standard cut | 500 kcal | ~0.45 kg / 1 lb |
| Aggressive (short-term only) | 750–1000 kcal | ~0.7–0.9 kg / 1.5–2 lb |
Why your estimate needs a feedback loop
Here's the part formulas can't do: TDEE calculators are a guess, not a measurement. Metabolism varies by more than the equations account for, and it shifts as you lose weight — a lighter body burns less at rest and in motion. The only way to know your real number is to track intake consistently for two to three weeks and compare it against what the scale actually does.
- Weight stayed flat? That intake is close to your true maintenance — your deficit starts from there.
- Weight dropped faster than expected? Your real TDEE is lower than estimated — small, common, easy to adjust for.
- Weight didn't move at all on a "deficit"? Almost always a logging gap, not a broken metabolism.
That last point is the one that sinks most attempts. Manual food diaries undercount by a wide margin — a bite here, a splash of oil there, a forgotten handful of nuts — and those small misses compound over a week into a very different number than the one you logged.
This is the exact gap PlateAI closes
Photograph a plate and get calories and macros back in seconds — no manual entry to skip on a busy day.
Adjust every two to three weeks, not every day
Weight fluctuates daily from water, sodium, and hormones — a single bad morning on the scale means nothing. Look at a 7-day rolling average instead, and only adjust your calorie target if that average has been flat for two to three consecutive weeks despite consistent logging. Drop another 100–150 calories, hold, and reassess.
The short version
- Estimate your TDEE, then subtract 300–500 calories to start.
- Log everything for two to three weeks — consistency matters more than precision on day one.
- Compare your weight trend to what the math predicted, and correct your number based on reality, not the formula.
- Re-adjust only every few weeks, using a weekly average, not a single weigh-in.
The formula gets you in the neighborhood. Consistent tracking is what actually finds your number — and the easier logging is, the more likely you are to still be doing it in week four, which is where the results actually show up.