A diagnosis of mental illness has been associated with weight gain, particularly among patients suffering from schizophrenia1.

This study aims to establish trends in weight gain among inpatients and the effects of several public health interventions between 2006 and 2009.

A body mass index (BMI) was calculated on admission and one of the authors has routinely measured the BMI of all inpatients on an annual basis since 2005 as part of a regular audit cycle.

Admission BMIs are comparable to the male general population2. The vast majority of patients are prescribed antipsychotic medication, approximately 50% receiving clozapine or olanzapine at any given time. There is a wide range of weight change from admission to discharge (−8.5 kg to +60 kg) but the average BMI of each sample exceeds the general population such that a majority of patients in each sample are clinically obese (BMI ≥30).In response to the audit findings the unit promoted public health and individual care plans (2006–09) aimed at addressing the high rates of obesity. Despite these initiatives there was a substantial rise in mean BMI between July 2007 and February 2008.

Admission to a medium secure unit results in substantial weight gain for the majority of patients. The causes of weight gain in a relatively closed institution are probably multi-factorial in origin.