The effects of alanine, glucose and starch ingestion on the ketosis produced by exercise and by starvation.

1. Several investigators have found that the development of post-exercise ketosis is not counteracted by glucose ingestion. Post-exercise ketosis might therefore have more in common with diabetic ketoacidosis than with starvation ketosis. 2. The effects of ingesting 100 g of glucose, alanine or starch were therefore studied in subjects rendered hyperketonaemic by prolonged running on a low carbohydrate diet, or by 65 h of starvation. These substances were also ingested by normal post-prandial subjects. 3. The runners developed post-exercise ketosis (1.81 +/- S.D. 0.81 mmol/l), which was counteracted by alanine and glucose, but only minimally by starch. 4. Fasting caused a variable ketosis (2.19 +/- S.D. 1.63 mmol/l), also counteracted by glucose and less by starch, but alanine caused vomiting. 5. Glucose and alanine lowered the blood ketone body levels of the post-prandial subjects. 6. The rising ketone body levels in starvation and after exercise were accompanied by simultaneous increases in the plasma insulin/glucagon ratios; in both, glucose ingestion increased the ratio further, while alanine decreased it. 7. It is concluded that there is no essential difference between established post-exercise and starvation ketosis, and that the blood fuel-hormone changes do not correlate with the changes in blood ketone body concentrations.