This study provides a sound basis towards a better understanding of the biochemical mechanisms behind childhood obesity and its metabolic phenotypes, which will be of great importance towards the development of more personalized prevention and treatment in future.

The aim of this study was to identify the plasma metabolic profile associated with childhood obesity and its phenotypes..

This cross-sectional study was set-up to examine the metabolic profile in fasting plasma samples from 65 overweight and obese (OB) children and 37 normal-weight (NW) controls aged 8 to 18 years. The obtained plasma 1H-NMR spectra were rationally divided into 110 integration regions, representing the metabolic phenotype. These integration regions reflect the relative metabolite concentrations and were used as statistical variables to construct a classification model in discriminating between OB and NW children and adolescents. In addition, two metabolic phenotypes were defined within the OB group, i.e. the metabolically "healthy" obese (MHO) and metabolically unhealthy obese (MUO) phenotype which are both classified as obese but with respectively, none (MHO) or at least two components (MUO) of the metabolic syndrome.

Inclusion Criteria:

• aged 8 to 18
• normal-weight, overweight or obese according to the International Obesity Task Force (IOTF) Body Mass Index (BMI) criteria
• fasted for at least 8 hours

Exclusion Criteria:

• Subjects taking any medication or having serious chronic or acute illness within two weeks preceding the clinical examination,

65 overweight and obese (OB) children and 37 normal-weight (NW) controls aged 8 to 18 years