Influence of weight perception on the evolution of body composition of adolescents under obesity treatment.

Obesity is a public health challenge, especially in adolescence, a stage characterized by physiological and behavioral changes that may influence energy balance, lifestyle choices, and long-term health trajectories. Although self-image place a significant role on weight perception, there is no consensus on the impact of self-perceived weight on actual weight development. While some studies suggest that underestimating weight may contribute to subsequent weight gain, others suggest the contrary. The aim of this study was to analyze the influence of weight perception on the evolution of body composition in adolescents followed in an Adolescent Obesity Clinic. An exploratory, longitudinal, retrospective study was carried out, analyzing data from 131 adolescents with obesity (BMI Z-Score ≥ 2.0), with valid data from at least two obesity appointments. 44.3% of the participants had a correct perception of their weight evolution; 41.4% perceived an increase, with real weight loss and 7.1% reported having no perception at all of their weight evolution. Lack of perception of weight evolution was associated with an increase in hip circumference (β = 1.021; 95%CI: 0.791 to 1.318; R2 = 31.6%; p = .012). The correct perception of weight gain, compared to the wrong perception of weight loss, was associated with a greater increase in BMI (respectively, β = 5.833; 95%CI: 2.223; 15.304; R2 = 67.2%; p < .001; β = .131; 95%CI: 0.003; 0.292; R2 = 85%; p < .001). CONCLUSION: Accurate perception of body weight changes may influence positively body composition in adolescents with obesity. WHAT IS KNOWN: • Adolescence is a critical developmental period for obesity, during which body image and weight perception play a central role in health behaviors and treatment engagement. • Weight status misperception is common among adolescents with obesity and may act as a barrier to effective weight management; however, data focusing specifically on adolescents under obesity treatment are limited. WHAT IS NEW: • In adolescents with obesity followed in a specialized clinic, inaccurate and lack of perception of weight change is highly prevalent, even under regular clinical monitoring, being associated with unfavorable changes in body composition. • Accurate perception of weight change emerges as a relevant factor linked to body composition evolution, underscoring the clinical importance of assessing and addressing weight perception during adolescent obesity treatment.