Methodological issues related to age of onset of obesity.

Research related to age of onset of obesity may be hampered by two methodological problems: (a) inconsistencies across studies in the criteria used to define early-onset and maturity-onset obesity and (b) the failure to control for other differences between early-onset and maturity-onset obese patients. Analyzing data from 178 applicants to a behavioral weight control program, this study found that almost twice as many patients were classified as early-onset obese when the division was based on their answer to the question, "Were you overweight as a child or teenager?" than when the division was based on self-reported weight at age 21. Moreover, early-onset obese patients were younger and heavier than those with maturity-onset obesity. Further studies are needed to determine the most reliable and valid means of classifying patients as early- or maturity-onset obese.