Postprandial insulin release is lower in healthy
aerobically trained (T) compared to untrained (UT) individuals.
This may be mediated by a lower release of the
two incretin hormones [glucagon like peptide-1 (GLP-1)
and glucose-dependent insulinotropic polypeptide (GIP)] in
T. The aim of this study was to assess and compare gut
hormone response and satiety changes after a liquid meal
intake in young, healthy T and UT males. Postprandial gut
hormone release and subjective feelings of hunger, satiety,
fullness and prospective food consumption were assessed
before and frequently for the following 3 h after a 200 ml
liquid meal (1,260 kJ and 27, 41 and 32 energy % as
protein, carbohydrates and fat, respectively) in ten T and
ten UT young, healthy male subjects. The insulin and GIP
responses were markedly lower in T than UT and correlated
during the first 30 min after the liquid meal. Baseline
GLP-1 concentration was higher in T versus UT, but the
response in the following 3 h after a liquid meal was
similar in T and UT. Satiety measures did not differ
between groups throughout the test. It is possible that in
aerobically T subjects, a lower GIP release is partly
responsible for a lower postprandial incretin stimulated
insulin secretion.