Training in portion-size estimation is known to improve the
accuracy of dietary self-reporting in adults, but there is no
comparable evidence for children. To obtain this information,
we studied 110 second- and third-grade American Indian schoolchildren
(34 control subjects were not trained), testing the hypotheses
that a 45-min portion-size estimation training session would
reduce children's food quantity estimation error, and that the
improvement would be dependent on food type, measurement type,
or both. Training was a hands-on, 4-step estimation and measurement
skill-building process. Mixed linear models (using logarithmic-transformed
data) were used to evaluate within- and between-group differences
from pre- to posttest. Test scores were calculated as percentage
estimation errors by difference and absolute value methods.
Mean within-group estimation error decreased significantly (
P < 0.05) from pre- to posttest for 7 of 12 foods (trained
group) by both calculation methods, plus 3 additional foods
by the difference method and one additional food by the absolute
value method. Significant (
P < 0.05) between-group differences
occurred for 3 foods, reflecting a greater decrease in estimation
error for the trained group. Improvement was greatest for solid
foods estimated by dimensions (
P > 0.05) or in cups (
P <
0.05), for liquids estimated by volume or by label reading (
P < 0.001), and for one amorphous food estimated in cups (
P < 0.01). Despite these significant improvements in estimation
ability, the error for several foods remained >100% of the
true quantity, indicating that more than one training session
would be necessary to further increase dietary reporting accuracy.
Key Words: Portion-size estimation • diet assessment • dietary intake • food quantity estimation • schoolchildren • obesity prevention • nutrition education • American Indian children
http://www.ajcn.org/cgi/content/full/69/4/782S