Introduction

Adolescence is a critical developmental period marked by rapid growth, pubertal change, and evolving lifestyle behaviors that influence long-term metabolic health [1]. Over recent decades, the prevalence of overweight and obesity among children and adolescents has risen substantially worldwide, with more than 340 million individuals aged five to 19 years affected globally by 2016 estimates [2]. India is experiencing a rapid nutritional and epidemiological transition, with urbanization, sedentary behavior, and dietary changes contributing to a dual burden of undernutrition and obesity. Indian studies report wide variation in adolescent overweight and obesity prevalence, with higher estimates generally observed in urban and higher socioeconomic groups [3,4].

Adolescent obesity is associated with early cardiometabolic abnormalities, including insulin resistance, dyslipidemia, hypertension, and clustering of cardiovascular risk factors [5,6]. Beyond overall adiposity, the distribution of adipose tissue is thought to be particularly relevant to this risk: visceral adipose tissue is metabolically active and has been linked, in other studies, to systemic inflammation, altered adipokine secretion, and insulin resistance [7-9]. The present study did not measure these downstream metabolic markers directly; rather, it examined visceral fat percentage as an anthropometric correlate, on the premise that accurate, non-invasive identification of visceral adiposity could support future risk-stratification efforts.

Body mass index (BMI) is the most widely used screening measure for overweight and obesity because it is simple, inexpensive, and feasible in clinical and community settings. However, BMI does not distinguish between fat mass and lean mass and provides limited information about body-fat distribution [10]. Adolescents with similar BMI values may have different degrees of visceral adiposity, particularly during periods of rapid growth and pubertal change [11]. Waist circumference (WC), waist-to-hip ratio (WHR), and waist-to-height ratio (WHtR) are commonly used alternatives that more directly reflect central adiposity and have been associated with cardiometabolic risk in pediatric and adult populations [12,13].

The conicity index (CI), introduced by Valdez, models the human body as a double cone and incorporates WC, body weight, and height into a single index of abdominal adiposity [14]. Adult studies have reported associations between the CI and cardiovascular risk, but its applicability in adolescents remains uncertain [15]. Theoretically, the CI could offer advantages over simpler anthropometric measures: by modeling the body as two conjoined cones, it is intended to capture abdominal shape independent of overall body size, and by incorporating weight and height alongside WC into a single dimensionless ratio, it aims to reflect the geometry of abdominal fat distribution rather than absolute girth alone [14]. We hypothesised that the CI would demonstrate a stronger association with visceral fat percentage than conventional anthropometric indices; whether this theoretical advantage holds in adolescents, who undergo rapid and heterogeneous changes in body composition, had not been adequately tested. This is important because adolescence is characterized by rapid and heterogeneous changes in body composition, fat distribution, and lean mass, all of which may affect the validity of anthropometric indices derived from adult geometric assumptions [16]. Despite increasing interest in composite anthropometric indices, evidence evaluating the CI specifically in overweight and obese adolescents remains limited, particularly in Indian clinical settings. The present study was therefore undertaken with two explicit aims: (i) to evaluate the correlation between the CI and bioelectrical impedance (BIA)-derived visceral fat percentage (VF%) among adolescents with overweight and obese, and (ii) to compare the CI’s predictive performance for VF% with that of conventional anthropometric measures, including BMI, WC, WHR, WHtR, abdominal volume index (AVI), and body adiposity index (BAI).