It is already known that obesity increases the risk of developing cardiovascular disease. However, a new study has found that this risk is lower among obese people who have a genetic predisposition for having a high body mass index (BMI) compared to those with obesity that has been mainly influenced by environmental factors, such as lifestyle.

According to Swedish researchers, almost one-third of the world’s population now lives with overweight or obesity, a figure they describe as “alarming”.

However, according to their findings, the risk of developing cardiovascular disease varies widely among people with obesity.

The team used data from over 15,000 twins enrolled in the Swedish Twin Registry. Information on their BMI and genetic predisposition for high BMI was gathered. Data from medical registries was also used to establish the incidence of cardiovascular disease among this group.

The researchers analysed the information in order to assess how overweight and obesity as a result of genetic versus environmental and lifestyle factors influenced the risk of cardiovascular disease.

“The link between obesity and cardiovascular disease was twice as strong in those with a genetic predisposition to a low BMI as it was in those with obesity driven by genetic factors,” explained one of the study’s authors, Dr Ida Karlsson, an assistant professor at the Department of Medical Epidemiology and Biostatistics at the Karolinska Institutet.

Dr Karlsson emphasised the importance of a healthy lifestyle, noting that the risk of cardiovascular disease was higher in all people with overweight or obesity compared to people of a healthy weight.

However, the findings also suggest that obesity that is mainly driven by genetic factors might not have the same adverse impact on health as obesity driven by other factors, such as lifestyle.

“Obesity is a complex common disease that can have many different causes. Since it’s so stigmatised, the results can help us understand that its effects on health differ from one individual to the next.

“Even though we all know that it takes more than exercise and diet to combat obesity, there’s still a large stigma attached to it. I think much could be gained by focusing on what has caused the obesity and what we can do to reduce the risk of comorbidities in each individual instead of mainly focusing on BMI,” Dr Karlsson said.

She explained that the next step in this research is to examine how individuals with overweight and obesity caused by genetic and lifestyle factors differ in relation to blood glucose levels, cholesterol and inflammation markers.

These findings are published in the journal, eClinicalMedicine, and can be viewed here.