Modelling study — 2011 — Energy balance · Body composition
Quantification of the effect of energy imbalance on bodyweight
What did the researchers investigate?
A mathematical model of adult metabolism that simulates how energy expenditure adapts as body weight changes.
What did they find?
Body weight responds slowly to a change in energy intake, with half-times of about a year. People with more body fat lose more weight for the same intake change, and take longer to reach a steady weight. As weight rises, energy intake must also rise to sustain it.
What does this mean for training?
A fixed calorie number does not stay right: as your weight changes, so do your energy needs.
How does FitX AI use this evidence?
FitX AI recalculates your calorie target from your latest weigh-in, so it moves as your weight moves.
Where FitX AI's own choices go beyond this paper
Calorie target. Activity multipliers and training energy are approximations. The target is an estimate and your real progress is the check. A typed target is the user's own number: FitX AI makes no claim for it, and its 1,200-6,000 kcal range and BMR warning are product choices.
Limitations
A model built on population data; individual responses vary.