Body fat percentages measured by dual-energy X-ray absorptiometry corresponding to recently recommended body mass index cutoffs for overweight and obesity in children and adolescents aged 3–18 y

• Published in: The American journal of clinical nutrition Vol. 76; no. 6; pp. 1416 - 1421
• Main Authors: Taylor, Rachael W, Jones, Ianthe E, Williams, Sheila M, Goulding, Ailsa
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Clinical Nutrition 01.12.2002
• Subjects: Absorptiometry, Photon; Adipose Tissue; Adolescent; adolescents; adults; Biological and medical sciences; Body Composition; body fat; Body Mass Index; Child; Child, Preschool; childhood obesity; children; diagnosis; dual-energy X-ray absorptiometry; epidemiology; equations; Female; females; Fundamental and applied biological sciences. Psychology; girls; Hemodynamics. Rheology; Humans; Male; males; Obesity; Obesity - diagnosis; Obesity - epidemiology; Reference Values; Sex Characteristics; Vertebrates: cardiovascular system; Human; Obesity; Adipose tissue; adolescents; Anthropometry; Nutrition disorder; Corporal biometry; Body composition; Overweight; Body mass index; dual-energy X-ray absorptiometry; X ray absorption spectrometry; School age; children; Dual energy absorptiometry; Adolescent; Percentage body fat; Diagnosis; Child; Nutritional status
• DOI: 10.1093/ajcn/76.6.1416
• ISSN: 0002-9165

Background: Body mass index (BMI; in kg/m2) cutoffs for use with children and adolescents aged 2-18 y that correspond to the well-accepted BMI cutoffs for overweight (greater than 25 but < 30) and obesity (≥ 30) in adults were published recently. Objective: The objective was to estimate the percentage body fat (%BF) values typically associated with these BMI cutoffs in children and adolescents. Design: The %BF was measured by dual-energy X-ray absorptiometry in 661 subjects (49% male) aged 3-18 y. Regression equations using BMI, age, and sex were developed to predict the %BF associated with BMI cutoffs for overweight (age-specific BMI equivalent to a BMI of 25 in an 18-y-old) and obesity (age-specific BMI equivalent to a BMI of 30 in an 18-y-old) over this age range. Results: Measurements classified 17.1% of males and 19.8% of females as overweight and 5.5% of males and 7.5% of females as obese. The %BF associated with an obese BMI tended to be higher in peripubertal males (34-36%) than in younger (24-30%) or older (27-30%) males. Although the predicted %BF of young females was similar to that of young males, values rose steadily with age, such that an 18-y-old female with a BMI of 30 had an estimated %BF of 42%, whereas that in males of similar age was 27%. Conclusion: The %BF values associated with BMI classifications of overweight and obesity vary considerably with age in growing children, particularly in girls.