Kohlenhydrat- und Fettstoffwechsel unter einer maximalen Ergometerbelastung bei hungernden Adipösen

Summary

The purpose of this investigation was to determine changes in lipid and carbohydrate metabolism induced by maximal work load after prolonged starvation.

Six obese men and 6 obese women (0) who had fasted totally for 3 weeks were compared with seven normal (N) controls. Bicycle ergometry was used, beginning with a low adaption load and then increasing the load step-wise 16.3 Watt/min to subjective exhaustion. Ergospirometry and arterial blood samples were assessed.

Results: The most extensive changes were seen before or at ten min after maximal work load. In the obese fasting patients glucose values rose steadily from 3.7 ± 0.3 to 4.7 ± 0.2 mmol/l while insulin and C-peptide decreased slowly. In 0 free glycerol rose (113 ± 19 to 360 ± 45 ymol/l), simultaneously released free fatty acids decreased (1.3 ± 0.1 to 0.9 ± 0.1 mmol/l) at maximal work load. At the same time a decrease in acetoacetate (419 ±9 to 256 ± 36 ymol/l) and β-hydroxybutyrate (4312 ± 510 to 3737 ± 504 ymol/l) was seen. Controls had the same changes in free glycerol, free fatty acids and ketone at maximal work load, but with lower basal values. Values of growth hormone and especially of catecholamines increased to high levels during exercise. After a 90 min resting period all values of 0 and N were back to pretest values.

Conclusions: In prolonged starvation increased lipolysis leads to an increase in free glycerol, free fatty acids and ketone bodies. At maximal work load lipolysis increases further as indicated by increased free glycerol, but free fatty acids and ketone bodies decrease surprisingly, suggesting a mechanism of active consumption. Hypoglycemia does not occur. Growth hormone and catecholamine values show a strong exercise-induced increase also after prolonged starvation.