If your weight does not decrease over time, you were not actually in a caloric deficit, despite what calculators or your estimates might suggest.

noli's read

This advice is based on the thermodynamic principle of conservation of energy, where weight loss requires a sustained energy deficit. Research confirms that individuals frequently underestimate their actual caloric intake and overestimate their energy expenditure when tracking food (meta-analysis, Trabulsi & Schoeller). It is accurate that calculators are only estimates based on averages and cannot perfectly predict individual metabolism. Where the statement is rigorous is in how it distinguishes 'theoretical' caloric intake (what one thinks they are eating) from 'actual' intake. There is no exaggeration here, as the claim conforms to the laws of human biology. The only complex point is adaptive metabolic variability, where the body can reduce non-exercise activity thermogenesis in response to prolonged restriction, which can make maintaining a deficit more difficult to measure in practice.

the sources

1. 1Hall KD, Heymsfield SB, Kemnitz JW, et al. 2012
2. 2Rolls BJ 2009