Subject:     [theglycemicindex] Good article
Date:     Mon, 24 May 2010 22:18:17 -0400
From:     David B. Klein <dbklein@sympatico.ca>
Reply-To:     theglycemicindex@yahoogroups.com
To:     Theglycemicindex@yahoogroups.com

Link: http://www.ajcn.org/cgi/reprint/87/2/303 
<http://www.ajcn.org/cgi/reprint/87/2/303>

*Background:* Clinical trials of low-fat diets characteristically^
produce small mean long-term weight loss but a large interindividual^
variation in response. This variation has been attributed to^
psychological and behavioral factors, although biological differences^
may also play a role.^

*Objective:* The objective was to determine whether physiologic^
differences in insulin secretion explain differences in weight^ gain
among individuals consuming low- and high-fat diets.^

*Design:* Of 276 individuals followed in the Quebec Family Study^ for a
mean of 6 y, we compared those in the lowest with those^ in the highest
dietary fat tertiles. We performed oral-glucose-tolerance^ tests at
baseline and examined the insulin concentration at^ 30 min (insulin-30)
as a proxy measure of insulin secretion.^ Six-year changes in body
weight and waist circumference were^ the primary endpoints. We
determined the associations between^ insulin-30 and the primary
endpoints by linear regression analysis,^ with adjustment for
potentially confounding factors.^

*Results:* Mean changes in body weight and waist circumference^ did not
differ significantly between the lowest- and highest-fat^ diet groups.
However, these endpoints were strongly associated^ with insulin-30,
especially among individuals consuming the^ lowest-fat diet. Insulin-30
at baseline was significantly associated^ with 6-y weight gain (/r/ =
0.51, /P/ < 0.0001) and change in^ waist circumference (/r/ = 0.55, /P/
< 0.0001) in the lowest^ diet fat, group (/r/ = 0.18, /P/ = 0.086), but
not in the highest^ diet fat group (/r/ = 0.20, /P/ = 0.058).
Individuals in the highest^ insulin-30 and lowest dietary fat group
gained 1.8 kg more than^ did those in the highest insulin-30 and highest
dietary fat^ group (51%; /P/ = 0.034); they gained 4.5 kg more than did
those^ in the lowest insulin-30 and lowest dietary fat group (6.5-fold;^
/P/ = 0.0026).^

*Conclusion:* A proxy measure of insulin secretion strongly predicts^
changes in body weight and waist circumference over 6 y in adults,^
especially among those consuming lower-fat diets, which demonstrates^
the existence of a novel diet-phenotype interaction.^