Goal-date calculator that bends
Most goal-date calculators divide by 7,700 and draw a straight line. That line is wrong: as you lose weight your body needs less to run, so the same meals leave a smaller and smaller deficit and progress flattens. This one recomputes your maintenance every day and shows you both answers.
Why the line bends
A smaller body costs less to run. Most of what you burn in a day is basal metabolism, and basal metabolism scales with body mass, so ten kilos down is a few hundred kilocalories a day cheaper to maintain. Hold your meals steady and the gap between what you burn and what you eat narrows every week. The straight-line calculators miss this, which is why their dates arrive and the scale has not.
What this actually computes
Your maintenance today is estimated with Mifflin-St Jeor and your activity multiplier. Subtract the deficit you chose and you get an intake, which is then held fixed — that is what people actually do. Each simulated day recomputes basal metabolism at your current weight, takes the difference against that fixed intake, and converts it to mass at 7,700 kcal per kilogram. The curve is what falls out; the straight line is drawn beside it for comparison.
Where 7,700 kcal per kilo comes from, and where it fails
It is the energy in a kilogram of body fat, and it assumes everything you lose is fat. Early loss is partly water and glycogen and arrives faster than the model says; later loss includes some lean mass and drains a little cheaper than pure fat. Adaptive thermogenesis — the body quietly spending less on movement and heat during a deficit — is not modelled here at all, and it usually pushes the real date later than even this curve. Treat the number as a floor on the time, not a promise.
The plateau is not a failure
If the goal sits below the weight at which your maintenance meets your intake, this tool says so instead of inventing a date. That is the honest answer: at that intake, the body settles. Reaching a lower weight then means eating less again or moving more — a decision worth taking deliberately rather than by drifting into it.
FAQ
Why is my date later than other calculators say?
Because they hold your maintenance fixed at today's value for the entire journey. Yours falls as you lose weight, so the deficit you started with is not the deficit you finish with.
Why will it not project a very low intake?
Below roughly 1,500 kcal for men and 1,200 for women it becomes hard to meet protein and micronutrient needs, and the loss that follows takes more muscle with it. That belongs with a professional, not a web page.
Does exercise change the answer?
It shifts the activity multiplier, which raises maintenance and so widens the deficit at the same intake. The effect is smaller than most people expect, and it also falls as you get lighter — moving a lighter body costs less.
Is anything I type here sent anywhere?
No. The whole projection runs in this page, and nothing is uploaded or stored.
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