How fast can I lose weight?

The projection derives a rate from the deficit you can hold rather than promising a figure. Aggressive deficits produce faster numbers on paper and worse adherence in practice, and the model deliberately keeps the gap sustainable rather than maximal.

Some lean mass is lost alongside fat in any deficit. The projection assumes about 25% of the loss comes from lean tissue, and that ratio is why resistance training and adequate protein appear in the action plan — they are what keeps the real number closer to the assumption.

Why is my waist projected to change by a different amount than my weight?

Waist is estimated from a separate anthropometric regression driven by body composition rather than by weight alone, so the two move together but not in lockstep. Both are estimates; the direction of travel is the useful signal.

Your fat-loss projection, in numbers

A deficit does not just remove weight — it changes the ratio between fat and lean tissue. This page models both, and shows where the waist is expected to move as a result.

Your details

Everything is calculated in your browser. Nothing is uploaded and no account is needed.

Height (cm)Weight (kg)AgeSexActivity levelGoal timeline

Fat versus lean: what a deficit actually removes

Losing weight always removes some lean tissue along with fat. BodyTrajectory models roughly 25% of the loss coming from lean mass and 75% from fat, which is a mid-range assumption for someone training and eating enough protein. Honest weight-loss projections state that ratio rather than pretending the scale only reads fat.

Your daily intake is derived from your estimated maintenance level minus a deficit, at about 7,700 kcal per kilogram, then the weekly rate is multiplied across your horizon. The report shows the resulting intake explicitly so you can sanity-check it against what you actually eat — a projection you cannot act on is decoration.

The low-body-fat safeguard

If your starting body fat is already at or near the healthy lower limit for your sex — about 10% for men and 18% for women — the model deliberately softens the deficit and holds your weight near where it is, instead of projecting further loss.

At that point additional loss comes mostly from lean tissue, which is not a result worth chasing. When this safeguard triggers, the report says so explicitly, so you are never left looking at an unchanged number without an explanation.

Where the numbers come from

Every number on this page comes from published sports-science formulas (Mifflin-St Jeor for basal metabolic rate, standard activity multipliers for total daily expenditure, and anthropometric regressions for circumferences). It is a calculation, not an AI-generated image and not a photograph.

Predictions are estimates for motivation, not medical, nutritional, or fitness advice. Circumference values come from anthropometric regressions based on your height, weight and body composition — not measurements.

Common questions

How fast can I lose weight?: The projection derives a rate from the deficit you can hold rather than promising a figure. Aggressive deficits produce faster numbers on paper and worse adherence in practice, and the model deliberately keeps the gap sustainable rather than maximal.
Will I lose muscle?: Some lean mass is lost alongside fat in any deficit. The projection assumes about 25% of the loss comes from lean tissue, and that ratio is why resistance training and adequate protein appear in the action plan — they are what keeps the real number closer to the assumption.
Why is my waist projected to change by a different amount than my weight?: Waist is estimated from a separate anthropometric regression driven by body composition rather than by weight alone, so the two move together but not in lockstep. Both are estimates; the direction of travel is the useful signal.