Public Release: 

Female prisoners more obese than general female population except in UK, whereas male prisoners are on average slimmer than the general male population

Lancet

The first systematic analysis of diet, exercise, overweight, and obesity in prison populations worldwide shows that while female prisoners are more obese than the general population (apart from in the UK), male prisoners are slimmer than men in the general population. The Article concludes that imprisonment is an opportunity to address major public health risk factors in vulnerable populations, and that failing to do will mean great costs to society. The Article is by Dr Katharine Herbert, Department of Public Health, University of Oxford, UK and colleagues.

Non-communicable diseases (NCDs) are increasingly viewed as a global health crisis, demonstrated by an escalating prevalence of diseases such as heart disease, stroke, diabetes, cancer, and respiratory disease. The four key modifiable risk factors identified for NCDs are smoking, alcohol, inadequate physical activity, and unhealthy diet. 3 in 5 deaths globally are now due to NCDs. Although prevalence of tobacco and alcohol use by prisoners has been assessed, no systematic review has been done of the other two key modifiable risk factors in prisoners: diet and physical activity.

The authors assessed 31 eligible studies, including more than 60 000 prisoners in 884 institutions in 15 countries. Male prisoners were less likely (by between 13 and 67%) to be obese than males in the general population in all but one study where they had the same likelihood of being obese. Female prisoners were 18% more likely to be obese than non-imprisoned women in the USA, and Australian female prisoners were also more likely to be obese than Australian women in the general population, but female prisoners in the UK were less likely to be obese than general population (the reasons for this were unclear).

Data on physical activity was only available for Australia and the UK but showed a contrasting picture in which UK prisoners were less likely to achieve recommended guidelines for physical activity, both by comparison with Australian prisoners and with the general UK population. Australian prisoners were more likely than the general population of the same sex to do more than 150 min of moderate exercise per week. The authors say: "This difference cannot be attributed purely to a cultural difference; something must be inherent in the structure of the prison environment that enables Australian prisoners to exercise."

The authors say that diet could go some way to explaining gender differences in the findings. They say: "the analysis of prisoner diets showed that while male diets in high-income countries provide an appropriate calorie intake, female diets provide a substantial excess of total energy. The evidence suggests that female prisoners are simply supplied with a diet designed for males."

They conclude: "Prisons present a unique public health opportunity for health promotion among vulnerable groups who are difficult to engage with in community settings... The costs to the individual and to society of failing to address these important public health issues are likely to be substantial. However, in view of the renewed interest in NCDs, recent calls for action, and the recognition of substantial inequalities in access to NCD prevention between and within countries, it is timely that prisons across the world should play an important part in NCD prevention. Studies in Australia and Japan describe how the prison regime can favourably influence NCD risk factors, thus showing that improvement of prison regimes and environments in such a way that favours health promotion and reduces modifiable risk factors is possible. The challenge remains to ensure that every prison provides a healthy diet and ample opportunities for physical activity."

In a linked Comment, Dr Frank W Arnold, Director of research, Oxford Wound Healing Unit, Medical rapporteur for Freedom from Torture and Helen Bamber Foundation, and Co-founder, Medical Justice Network, says: "In countries where the frequency and duration of incarceration are rising, the incidence and consequences of non-communicable diseases will inevitably increase in parallel with an ageing population in jail. An increase in the incidence of non-communicable diseases will magnify problems associated with management of disorders such as diabetes and epilepsy, and prisoners could be accused (rightly or wrongly) of manipulating their treatment for nefarious ends, potentially resulting in dangerous neglect."

He concludes: "Ultimately, the most important potentially modifiable factor in prisoners' environment is imprisonment itself. Since much international variation exists in the rates at which people are incarcerated and the reasons why this happens, there seems to be substantial scope for beneficial reform. But such reform is a political question, not a medical one."

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Dr Emma Plugge, Department of Public Health, University of Oxford, UK. T) +44 (0) 1865 289225 E) emma.plugge@dph.ox.ac.uk

Dr Frank W Arnold, Director of research, Oxford Wound Healing Unit, Medical rapporteur for Freedom from Torture and Helen Bamber Foundation, and Co-founder, Medical Justice Network, UK. T) +44 (0) 7740422918 E) arnold_frank@hotmail.com

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