Plan the time, not just the calories
Weight Loss Timeline Calculator
Estimate how long a sustainable calorie target might take as your weight and energy needs change.
Build your timeline
Estimated timeline
Planning range, not a guarantee or statistical confidence interval.
Weight loss usually slows as body weight and energy needs decrease. FitCalc recalculates the energy gap through the projection instead of assuming the first weekly rate continues forever.
Projected trend
Projection checkpoints
| Week | Projected weight | Estimated maintenance |
|---|
Why this is not a 3,500-calorie countdown
The familiar rule assumes the same energy gap continues indefinitely. In practice, energy needs generally decline as body weight falls. FitCalc iterates the calculation day by day using changing maintenance estimates and a constant planned calorie target.
Use the estimate as a calibration plan
Compare your actual multiweek weight trend with the projection. Recalculate after roughly 2–4 weeks when the trend differs meaningfully, your intake changes, or your activity changes.
Important limitations
This educational planner is intended for generally healthy adults. It is not for children, pregnancy or breastfeeding, eating-disorder treatment, or medical weight-loss care. Water, glycogen, body composition, adherence, medication, and individual metabolic responses can materially change the outcome.
Does FitCalc reproduce the NIH Body Weight Planner?
No. FitCalc uses a simpler transparent iterative model built on its existing maintenance calculation. The NIH model includes additional physiology and is the better reference for a research-grade simulation.