AJP - Endocrinology and Metabolism, Vol 272, Issue 2 E248-E254, Copyright © 1997 by American Physiological Society
Negative energy balance with exercise in identical twins: plasma glucose and insulin responses
J. M. Oppert, A. Nadeau, A. Tremblay, J. P. Despres, G. Theriault and C. Bouchard
Nutrition Department, Hotel-Dieu Hospital, Paris, France.
The effects of long-term (93 days) negative energy balance on plasma
glucose and insulin were investigated by means of exercise with constant
energy intake in seven pairs of young sedentary male identical twins.
Results showed a significant decrease in fasting (-24%, P < 0.02) and
postprandial insulin (-16%, P < 0.05). Fasting and postprandial plasma
glucose and glucagon were not modified. Mean glucose disposal rate measured
during a euglycemic-hyperinsulinemic clamp performed in five twin pairs was
increased by 34% (P = 0.13). No significant intrapair similarity was found
for the responses of fasting and postprandial insulin levels and of glucose
disposal rate. Changes in glucose disposal rate were significantly greater
in high compared with low losers for computerized tomography-measured
abdominal visceral fat (3.0 +/- 1.1 vs. 0.3 +/- 0.5 mg x kg(-1) x min(-1),
P < 0.05) despite similar losses in total body fat. We conclude that 1)
a long-term negative energy balance generated by exercise training
significantly reduces plasma insulin levels, whereas insulin sensitivity
tends to be improved; 2) training-induced changes in insulin sensitivity
are associated with changes in abdominal visceral fat; and 3) data from
this experiment conducted with a small number of twin pairs suggest that
the genotype does not seem to be a major determinant of the changes in
insulin levels and sensitivity brought about by negative energy balance
with exercise.
