Ketosis in patients undergoing medically supervised therapeutic fasting-results from an observational trial.

Background/aim: Medically supervised fasting has long tradition and broad acceptance in some European countries. The exact amount to which ketone bodies are produced as well as their possible contribution to beneficial effects in this procedure are open.

Methods: Open-label observational trial with in-patients undergoing medically supervised fasting with supplementation of approximately 40 g/d carbohydrates as part of an established routine care. Daily finger-stick blood samples for measurement of glucose and ß-hydroxybutyrate. Descriptive analysis for all data.

Results: Complete sets of data of 17 patients (5 m, mean age 63.1) could be evaluated. Mean concentrations of ß-hydroxybutyrate rose continuously to a mean maximum of 3.6 mmol/L with an individual maximum of 5.1 mmol/L, while glucose decreased within normal range. Two patients with type 2 diabetes produced significantly less ß-hydroxybutyrate. Courses for ß-hydroxybutyrate and glucose showed a weak inverse correlation, while no serious adverse effects could be observed.

Conclusion: Medically supervised fasting with definite small amounts of carbohydrates by fluid intake may lead to limited increases of ketone bodies in their biopositive range, as known e.g. from epileptology or sports medicine. Clinical consequences deserve further research.