Endocrine Abstracts

The opportunity to study the effects of prolonged fasting is rare. In this study we recorded anthropometric, biochemical and endocrine changes during the refeeding period following a 44 day fast, and compared them with results from 16 age-, sex- and body mass index (BMI)-matched controls.

The index subject took only water to drink during the fast. He lost 24.5kg changing his BMI from 29 to 21.6. He underwent careful slow refeeding for the first 4 days using nutritionally complete liquid formulation and vitamins. His metabolic status on arrival in hospital showed preserved blood sugar, normal cholesterol and triglycerides but elevated free fatty acids and much elevated hydroxybutyrate. B1, B6 vitamins and folate were depleted and required early replenishment for safe refeeding. Haemoconcentration was observed on day 0 and slight oedema by day 10 despite low salt intake. A transient hypophosphataemia was observed on day 1 and was corrected by phosphate replacement. Grossly elevated B12 levels, high zinc levels and slightly abnormal liver functions were also observed. levels and high IGFBP1, somatostatin and cortisol levels, low normal insulin levels and very low IGF-I, leptin and ghrelin were observed at the end of the fast, while PYY, adiponectin, AGRP, alpha-MSH, NPY and POMC showed no markedly different values from the samples of control subjects after an overnight fast. His feeling of hunger increased considerably on day 4 and this was preceded by elevation of plasma orexin and resistin on day 3.

Finally, his appearance after the fast reflecting a BMI of 21 would not have alerted us to the risks of refeeding had we not known about the fast and weight loss. In the event, despite great caution, he exhibited important elements of the refeeding syndrome with hypophosphataemia and fluid retention and displayed signs of abnormal IGF axis and liver function.