Individuals with hyperphagia can voluntarily fast: Experience from Prader-Willi Syndrome

Relentless pursuit of food is a major characteristic of Prader-Willi Syndrome (PWS). We observed voluntary fasting among PWS individuals during a religious fast. Understanding the mechanisms involved in successful fasting could be an important contribution in developing more effective treatment of this syndrome. We conducted a prospective study to assess whether genotype, motivational attitudes (e.g. religiosity) and control patterns (e.g. different eating habits) would correlate with ability to fast. Among all individuals with PWS in Israel, 32 met inclusion criteria. Prior to the fast, each participant and parents/caregivers were interviewed for demographic, medical and behavioral data and completed questionnaires assessing motivational and control factors. 22 participants completed the fast. This ability was not accounted for by religiosity, demographic, medical variables or genetic subtype. This prospective study documents that in spite of extreme hyperphagia, adolescents and adults with PWS can voluntarily abstain from food for 25 hours; our findings suggest that they are able to activate mechanisms which improve their control of eating for a longer period than expected. The observation that the degree of religiosity did not impact on the ability to fast suggests that these mechanisms may be applicable to a wider range of circumstances and populations. The ability for self-control under special circumstances deserves further study; it may be relevant to other types of severe obesity and possibly lead to improved methods of behavioral modification.