Body Mass Index (BMI), as an adiposity indicator, assumes that for any given height a change in weight is attributed to a change in fat. This seems problematic in growing youth as great divergence is evident in bone, muscle, and adipose tissue development. Secondly, use of reference populations in categorizing children based on BMI, frequently use arbitrary percentile cut-offs for obesity and do not meet all of the assumptions that cut-offs imply. Lastly, BMI does not control for maturation status. Criterion-referenced assessments of child obesity that account for abdominal adiposity and permit international comparisons, such as waist-to-height ratio (WtHR), must be considered. Better predictive utility has been demonstrated when using WtHR for abdominal adiposity and cardiovascular risk factors in youth compared with BMI. Although multiple methods for assessing waist circumference may be problematic for comparison purposes, its simplicity and international comparability aspects make it a promising alternative to BMI.