A study published in The Lancet Public Health shows a clear relationship between body weight and hospital admissions and costs, with increased admissions and associated costs for older women who are overweight or obese. 

15% (£662 million) of annual hospital costs for the 6.6 million women aged 55 to 79 in England in 2013 were related to being overweight or obese.  

The most common hospital treatments linked to being overweight were for musculoskeletal conditions particularly knee replacement surgery. Diseases of the circulatory system, digestive system and cancers also contributed substantially to costs attributed to overweight and obesity. People who are overweight or obese have an increased risk of developing Type 2 diabetes. Although diabetes is not commonly the primary diagnosis at admission, a number of complications can result from the condition which have associated treatment costs.

The results highlight the areas of hospital care where excess weight is likely to have the greatest impact. They also support calls for greater investment in cost-effective interventions to reduce weight or prevent weight gain.

The degree to which a person is overweight is generally described by body mass index (BMI) which is shown as body weight in kilograms per height in metres squared. Overweight is defined as having a BMI of 25 to less than 30 kg/m2 and obesity as a BMI of 30 kg/m2 or more.

The study used data from the large prospective Million Women Study which recruited over 1 million 50 to 64 year old women in England from 1996 to 2001. Among these women 47% had a healthy weight (BMI 18.5 to 25 kg/m2), 36% were overweight and 18% were obese. 

Data on hospital admissions and deaths were collected on all women until the end of March 2011. Annual admissions, overall admissions costs and costs for groups of health conditions, based on the primary diagnosis at admission, were estimated by BMI and extrapolated to the 2013 population of 6.6 million women aged 55 – 79 in England.

Seamus Kent, lead researcher said “Admission rates and costs were lowest for women with a BMI of between 20 and 22.5 kg/m2. Among 1,000 such women, we would expect to see around 320 admissions per year, with an annual cost per woman of £570. We found that admissions increase steadily with higher BMIs, reaching 530 admissions per 1,000 women and a cost of £1,220 per woman at BMI of 40 kg/m2 or more.”