Normal-Weight Obesity and Hidden Cardiometabolic Risk in Young Adults: Implications Beyond BMI-Based Classification

Area of Science:

• Metabolic Health
• Cardiovascular Risk Assessment
• Obesity Phenotyping

Background:

• Body Mass Index (BMI) is a common obesity measure but doesn't fully capture adiposity distribution or metabolic risk.
• Normal-weight obesity (NWO), characterized by excess fat despite normal BMI, is linked to increased cardiometabolic risk.
• The prevalence and implications of NWO in young adults are not well-understood.

Purpose of the Study:

• To determine the prevalence of NWO in young adults.
• To investigate the association between NWO and cardiometabolic risk markers in this population.

Main Methods:

• A cross-sectional study of 12,874 adults aged 22-30 years undergoing occupational health assessments.
• NWO defined by strict (waist-to-height ratio ≥ 0.5) and expanded criteria (including body fat percentage, visceral fat).
• Analysis of anthropometric, adiposity, biochemical, and lifestyle data using multivariable logistic regression.

Main Results:

• NWO prevalence was 1.79% (strict) and 2.30% (expanded) among normal BMI individuals.
• NWO individuals had higher triglycerides, fasting glucose, and atherogenic lipids, with lower HDL cholesterol compared to metabolically healthy peers.
• NWO was independently associated with elevated triglycerides (OR 4.99), unfavorable triglyceride-to-HDL ratio (OR 7.44), and impaired fasting glucose (OR 3.87).

Conclusions:

• NWO is prevalent in young adults and linked to adverse cardiometabolic markers despite normal BMI.
• The triglyceride-to-HDL ratio strongly correlates with NWO and adiposity phenotypes.
• Findings underscore the limitations of BMI alone, advocating for additional markers to identify at-risk individuals.