Study suggests one-third of US homeless are obese

A new study dispels the myth that in general the homeless are starving and underweight. New research by Oxford University and Harvard Medical School has found that obesity is just as common among the homeless as it is among the general non-homeless population.

The study, to be published in a forthcoming issue of the Journal of Urban Health, suggests this could be because cheap foods that are instantly satisfying often contain high levels of fats and sugars. Another reason could be that bodies experiencing chronic food shortages adapt by storing fat reserves.

Researchers examined the body mass index (BMI) data of 5,632 homeless men and women in Boston, and found that nearly one-third of them were obese. They used the medical electronic records at 80 hospital and shelter sites for the homeless in Boston, using data from the Boston Health Care for the Homeless Program, one of the largest adult homeless study populations reported to date.

They found that just 1.6% of the homeless in the sample could be classed as 'underweight'. Morbid obesity – where people are 50%-100% above their ideal body weight – was three times more common with 5.6% of homeless adults classed as morbidly obese.

The study authors also compared the BMI of the US homeless adults with 5,555 non-homeless adults, using data from the National Health and Nutrition Examination Survey. They found that obesity amongst the homeless (32.3%) was almost as high as among the general population (33.7%).

The mean BMI among homeless adults was 28.4 kg per metre squared compared with 28.6 kg per metre squared among the general non-homeless population. However, homeless women had a significantly higher percentage of obesity (42.8%) than non-homeless women (35.3%). 

Factors associated with being homeless, such as a largely sedentary lifestyle, sleep debt, and stress may also contribute to the high prevalence of obesity, the study suggests. The researchers express caution about what the precise risk factors and causes of obesity in the homeless might be. However, the study offers a range of hypotheses and suggests this could be a ripe area for future research.

Lead study author Katherine Koh, who carried out the research at the University of Oxford but is now at Harvard Medical School, said: 'The recently described "hunger-obesity paradox", which describes the co-existence of hunger and obesity in the same person, may help explain these findings. The rise of obesity among populations that lack regular access to food has recently been documented in developing countries and certain low-income populations.

'This research shows that this paradox may affect homeless people as well. Obesity among the homeless population could be due to the tendency to buy cheap, low-nutrient dense but highly caloric foods in the setting of limited resources. Another factor could be the physiological changes that occur in the body in the face of inconsistent food intake.'

Co-author Paul Montgomery, Professor of Psycho-Social Interventions at the University of Oxford, said: 2To our knowledge, this is the first study to rigorously evaluate whether obesity is a problem among the homeless in the US as very little research has been done in this area. This study highlights the importance of the quality, as well as the quantity, of food that the homeless are consuming.

'Interventions aimed at reducing obesity in the homeless, such as improving nutritional standards in shelters or educational efforts at clinical sites, should be considered in the light of these findings.'

This study supports other academic literature in the United States that demonstrates that the highest prevalence of obesity now exists in low-income groups. The study concludes that although being underweight has traditionally been associated with homelessness, obesity may have replaced underweight as the new malnutrition of the homeless.