Tracking of obesity and body fatness through mid-childhood.
OBJECTIVE
To explore how fat, lean and body mass index (BMI) track in childhood and how this relates to parental obesity.


METHODS
Prospective population-based cohort study: Avon Longitudinal Study of Parents and Children, UK.


METHODS
Height, weight and leg-to-leg bioelectrical impedance (BIA) were collected at ages 7 and 11 years, as well as pre-pregnancy parental heights and weights. For BMI International Obesity Task Force thresholds of obesity and overweight were used. Impedance data were expressed as separate lean and fat z scores, internally standardised for gender, height and age and a child was defined as over-fat if fat z score was >85th and very over-fat if >95th internal centile.


RESULTS
Data were available for 7723 and 7252 children at ages 7 and 11 years, respectively (6066 at both time points). Of those obese at age 7, 75% were still obese at age 11, while of those who had been overweight 16% had become obese and 20% now had normal BMI. Both fat and lean z scores showed moderate levels of tracking (correlation coefficients 0.70 and 0.73, respectively). Children with one or two obese parents had higher fat z scores at age 7 and showed greater increases in fat thereafter. They were more likely to be very over-fat at age 7 and, of these, 69% remained so at age 11 compared to only 45% with non-obese parents (p <0.001).


CONCLUSIONS
Children of obese parents already have high fat levels at age 7 and are more likely to remain very over-fat.
Department of Child Health, Division of Developmental Medicine, University of Glasgow, Glasgow, UK. cmw7a@clinmed.gla.ac.uk
C M
CM
Wright
P M
PM
Emmett
A R
AR
Ness
J J
JJ
Reilly
A
A
Sherriff
D050154:Adiposity; D000886:Anthropometry / Q000379:methods; D001823:Body Composition; D001827:Body Height / Q000502:physiology; D015992:Body Mass Index; D001835:Body Weight / Q000502:physiology; D002648:Child; D017097:Electric Impedance; D004739:England / Q000453:epidemiology; D005192:Family Health; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009765:Obesity / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D050177:Overweight / Q000453:epidemiology / Q000503:physiopathology; D010290:Parents; D011627:Puberty / Q000502:physiology; D012737:Sex Factors