Background. The phenomenon of "weight loss plateau" is not fully understood, and because of this practitioners may reasonably have difficulties in determining its truth or falsity; there is no clear boarders to identify this condition. Aims. To generate diagnostic criteria of "weight loss plateau" phenomenon useful for estimating the rate of weight gain dynamics in the treatment of obesity. Materials and methods. Statistical analysis of basal metabolism (BM) calculated level (the sample mean and sample standard deviation) on the basis of potential mathematically matched anthropometric data with subsequent determination of the proportion of these BM values difference in overweight and obesity patients, and numbers of the desired weight. Results. Formation of a numeric array on theoretically inherent output, obtained the average proportion of the difference between present BM values and recommended indicators that are proposed to be guided to determine the phenomenon of "weight loss plateau" in the process of diet therapy of obesity. Conclusions. Authors offer available for using algorithm, which allows establish the potential availability of "weight loss plateau" phenomenon and its truth or falsity on different stages of weight loss process in obesity. These arguments need further scientific dialogue and research.