Submitted to: Journal of the American Medical Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/1999
Publication Date: N/A
Citation: N/A Interpretive Summary: Obesity is increasing among children in the United States. Studies have shown that parental obesity more than doubles the risk of adult obesity among children under 10. We wanted to examine the energy expenditure of children of obese vs lean parents, theorizing that it is lower in girls with a familial predisposition to obesity. We used sophisticated methods to oevaluate the energy expenditure of girls in three groups; one group had tw lean parents, the second group had one lean and one obese parent, and the third group had two obese parents. The results indicated that energy expenditure was similar among the familial groups. However, when grouped according to ethnicity, the African-American girls had lower energy expenditure than the Caucasian girls. Based on the results, we conclude that energy expenditure does not differ in normal-weight, prepubertal girls predisposed to obesity, but it does differ according to ethnicity.
Technical Abstract: The prevalence of childhood obesity is increasing and the causes are unknown. Objective: To determine whether energy expenditure (EE), measured by 24-hour calorimetry and doubly labeled water, differs among normal- weight-for-height, multiethnic, prepubertal girls whose parents are lean, obese or both. Design: Cross-sectional study conducted from 1995-1998 in Houston, TX. Participants: Caucasian, African-American and Hispanic prepubertal girls (mean age +/-SD = 8.5+/-0.4 years). Girls in group LN (n=30) had two lean parents; girls in group OB (n=27) had two obese parents; those in group LNOB (n=44) had one lean and one obese parent. Each parent was classified by body mass index as lean (<25 kg/m2) or obese (>28 kg/m2). Measures: Basal metabolic rate (BMR), sleeping metabolic rate (SMR), 24-hour EE, respiratory quotient (RQ), heart rate, and activity measured by 24-hour room calorimetry; free-living TEE, activity EE and physical activity level (defined as free-living EE/BMR) measured by doubly labeled water. EE was standardized by fat-free mass (FFM). Results: There were no differences among familial groups for weight, height, fat mass, FFM and % fat; however, ethnic effects were observed for weight and FFM. The African-American girls had higher FFM than either the Caucasian or the Hispanic girls (P<0.05). BMR, SMR, 24-hour EE, RQ, heart rate and activity counts were similar among familial groups. No significant familial group differences in free-living TEE, activity EE or physical activity level (LN=1.60+/-0.05, LNOB = 1.64+/-0.04, and OB=1.58+/-0.05) were observed. However, BMR, SMR, and free-living TEE were lower in African-American than Caucasian girls (P<0.05). EE does not differ in normal-weight prepubertal girls predisposed to obesity, but does differ according to ethnicity.