Scientists from Bristol Medical School investigated whether being overweight at different stages of life contributed towards disease risk. They believe lowering weight in adulthood through lifestyle changes could reduce the long-term adverse effects of childhood obesity.
Tom Richardson, of Bristol Medical School’s MRC Integrative Epidemiology Unit, said: “Our findings for coronary heart disease and type 2 diabetes suggest that, if changes to genetically predicted early life equate to weight change through diet and exercise, then there exists a window of opportunity between childhood and adulthood to mitigate the effect of childhood obesity on disease risk.”
The researchers used a technique known as Mendelian randomisation, which takes into account a person’s genetic code along with other data to identify health risks.
They examined the genetic influence of body size in early life on risk of four diseases in later life - coronary artery disease, type 2 diabetes, breast cancer and prostate cancer.
The technique was applied using genetic data from 453,169 people from the UK Biobank study, which contains biomedical information of tens of thousands of individuals, as well as four large-scale genome-wide association studies comprising more than 700,000 people.
Along with the data on body mass index (BMI) information on self-perceived body size at the age of 10 was also included.
The research, published in the BMJ, found childhood obesity to be associated with increased risk of coronary heart disease and type 2 diabetes in cases where people tended to remain overweight as adults. They also found larger early life body size to have a “protective effect” on breast cancer risk, but added further investigations are required before firm conclusions can be made.
Dr Richardson said: “Our findings on breast cancer raise questions about the role that timing of puberty has on later life disease risk and further research is required to develop the most effective preventative strategies related to it.”
The researchers said they did not uncover any evidence of a causal effect of either early or later life measures on prostate cancer but added that further studies are required.
However, the authors also point out that relying on self-reported early life body size may affect the accuracy of their estimates.
In a linked editorial, Prof Mary Schooling, of the Graduate School of Public Health and Health Policy in New York, said the findings “need careful interpretation and contextualisation before they can be applied to population health”.