Outcome measures
Anthropometric measurements were taken at intervals of six
months. Height (without shoes) was measured by one investigator
(JJ) to the nearest 0.1 cm with the Portable Leister height
measure (Seca, Marsden, United Kingdom). Weight (in light
clothing) was measured to the nearest 0.1 kg on medical scales
(Seca 770, Marsden).Waist circumference was measured according
to published centile charts.8 We converted body mass index
(weight (kg)/(height (m)2)) to standard deviation scores (or z
scores) and to centile values using the British 1990 growth reference
disc (Child Growth Foundation, London).9
The children completed diaries at baseline and at the end of
the trial on drinks consumed over three days. Records were
made over two weekdays and one weekend day. Collecting
dietary data in this way has been shown to provide comprehensive
results.10