Public Health Bulletin

Body mass index (BMI) is a measure of body fat based on height and weight, it is calculated by dividing a person’s weight in kilograms by height in meters squared. BMI of 20 to <25kg/m2 is considered a healthy weight. BMI of ≥25kg/m2 is considered excess weight, which can be further classified as overweight, obese, or severely obese. 

Around 63% of adults in England are living with excess weight. In Hackney, around 48% of adults, 25% of Reception children, and 42% Year 6 children are living with excess weight.

Excess weight affects all population groups but is higher for those people aged between 55-74 years, people living in deprived areas and in some Black, Asian and Minority Ethnic (BAME) groups compared with the general population. Evidence shows that the health risk of excess weight for some BAME groups occurs at a lower BMI than for White populations.

According to the Global Burden of Disease Study 2018, high BMI is the third biggest lifestyle risk factor contributing to premature morbidity and mortality in the UK. Living with excess weight is a risk factor for type 2 diabetes, cardiovascular disease, many cancers, liver and respiratory disease. Obesity is also associated with reduced life expectancy and lower quality of life. 

A recent review of the evidence suggests that excess weight is associated with an increased risk of testing positive for Covid-19, hospitalisation, advanced levels of treatment, and death. The risks seem to increase progressively with increasing BMI even after adjustment for potential confounding factors, including demographic and socio-economic factors. There is also some evidence to suggest that disparities in excess weight may explain some of the observed differences in outcomes linked to Covid-19 for older adults and some BAME groups. 

• The likelihood of testing positive for Covid-19 increases as BMI increases 
• BMI is more strongly related to testing positive in BAME groups compared with White ethnic groups 
• These findings may be affected by selection bias primarily due to the testing strategy in place at the time the studies were carried out

• Persons with excess weight are at a progressively increased risk of being hospitalised if infected with Covid-19 compared with those of a healthy weight

• Excess weight patients are more likely to be admitted to intensive/critical care and to require advanced treatment for severe Covid-19 symptoms compared with those of a healthy weight 

• There is potentially a higher risk of Covid-19 related death with increasing BMI
• The relationship between excess weight and Covid-19 risk has persists even after adjusting for confounding factors such as age, sex, measures of socio-economic status, ethnicity and co-morbidities

• Stigma experienced by people living with obesity, may delay interaction with health care and may also contribute to increased risk of severe complications arising from Covid-19

It is currently unclear to what extent the relatively high prevalence of excess weight seen in the UK, compared with other countries, may have contributed to the severity of Covid-19 in the UK. In addition, it is uncertain to what extent differences in the prevalence of excess weight for different population groups have contributed to inequalities in outcomes. Supporting people who are living with excess weight to lose weight could reduce future population risks of Covid-19.