The "Housing First" approach of giving homeless people with mental illness a place to live without any preconditions such as sobriety or enrollment in a psychiatric treatment program has many benefits. But losing weight isn't one of them.

People experiencing homelessness have high rates of overweight and obesity, which are associated with increased risk of poor health, many chronic diseases and premature death.

Researchers at St. Michael's Hospital wondered if having stable housing would lead to weight loss since access to housing means people have the opportunity to buy, store and prepare food of higher nutritional value than they would previously have had. In addition, making the transition to stable housing may be part of an entire lifestyle modification that includes healthier eating.

But their findings, published in the journal PLOS ONE, found that was not the case.

Neither the Body Mass Index nor the waistline circumference of people involved in their study changed significantly over 24 months.

Senior author Dr. Stephen Hwang, director of the hospital's Centre for Research on Inner City Health, said the people involved in the study all had serious mental illness and if they started a treatment program they could have been prescribed psychotropic drugs that can result in weight gain or loss. Changes in drug and alcohol use can do the same.

"Our findings suggest we need a better understanding of factors contributing to overweight, obesity and high waist circumference in people who have a history of precarious housing and poverty as well as other concerns such as mental illness and additions," Dr. Hwang said.

This study involved data from 575 people enrolled in the Toronto site of the Mental Health Commission of Canada's At Home/Chez Soi, a research project that evaluated a "housing first" approach, where people are first provided with a place to live, without preconditions such as sobriety or seeing a psychiatrist, and then provided additional supports and services as needed. The underlying principle is that people are better able to move forward with their lives if they are first housed.