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 (−8.5kg to +60kg) 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.