Diabetes, Vol 42, Issue 7 1010-1016, Copyright © 1993 by American Diabetes Association
Time course of increased lipid and decreased glucose oxidation during early phase of childhood obesity
C Le Stunff and PF Bougneres
Hopital Saint Vincent de Paul, Paris, France.
To determine the time course of metabolic dysfunctions in recent active
obesity, we studied basal energy expenditure and lipid and glucose
oxidation in 31 obese children (duration of obesity 1-11.5 yr), compared
with 14 lean age-matched control subjects. Using indirect calorimetry in
basal overnight fasting conditions, we found that obese children produced
15% more energy than control subjects. Obese children oxidized twice as
much lipid (56 +/- 4 mg/min) as normal children (25 +/- 5 mg/min, P <
0.0005), so that lipid oxidation provided 61 +/- 6% of overall energy
production (vs. 33 +/- 3% in control subjects, P < 0.0005). This
increase of lipid oxidation was already present in the earlier stages of
obesity. Glucose oxidation was diminished in the obese (93 +/- 6 mg/min)
compared with the control children (136 +/- 6 mg/min, P < 0.0005) and
accounted for only 39 +/- 3% of energy production (67 +/- 6% in control
subjects, P < 0.0005). This decrease was not present initially and
appeared after approximately 4 yr and worsened with obesity duration (r =
0.72, P < 0.0005). The results were similar when lipid and glucose
oxidation were normalized to body surface area or lean body mass. We
hypothesize that increased lipid oxidation is one of the earlier
dysfunctions observed in recent-onset obesity and that lipid oxidation may
induce a progressive decrease of glucose oxidation, insulin resistance, and
increased fasting insulin secretion.