More years of obesity means higher risk of disease – new study

Blood pressure, cholesterol, and high blood sugar are worse for people who have been obese for longer, according to a new study.

Researchers at Loughborough University have found a link between the length of time someone has spent above the obesity threshold – based on the BMI scale – and levels of blood pressure, cholesterol and HbA1c.

Glycated hemoglobin (HbA1c) is caused when sugar attaches itself to red blood cells.

High levels of HbA1c are an indicator of developing diabetes and related complications – it is also linked to elevated risk factors related to heart disease and stroke.

In a study of more than 20,000 people, one key finding showed that even after accounting for severity of obesity, the longer someone spends obese the worse the level of blood sugar (HbA1c).

This is not the same for the other risk factors.

The study showed that adults with less than five years of obesity had a 5% higher HbA1c compared to adults with no years of obesity.

For adults with 20-30 years of obesity, HbA1c was 12% higher.

Dr Tom Norris, of the School of Sport, Exercise and Health Sciences (SSEHS), lead author of the paper, said: “The motivation for the study was to try and understand why some people with obesity have a greater risk for diseases that affect the circulatory and endocrine systems than other people who also have obesity.

“We tested the idea that the length of time a person has obesity is responsible.

“We found that longer time with obesity resulted in worse blood pressure, cholesterol, and HbA1c.

“Importantly though, greater obesity duration was still associated with worse HbA1c even after accounting for obesity severity. This was not true for blood pressure and cholesterol.”

The study used data from three British birth cohort studies (20,746 participants) that collected information on body mass index from age 10 to 40 as well as cardiometabolic disease risk factors—blood pressure, cholesterol and HbA1c measurements.

Other measures of cardiometabolic disease risk (systolic and diastolic blood pressure, high-density lipoprotein cholesterol) were also associated with obesity duration, though these associations were largely attenuated when adjusting for obesity severity.

Senior author of the paper Dr Will Johnson, also of SSEHS, added: “The results suggest that developing obesity earlier in life may be related to worse HbA1c even if obesity severity is low.

“For example, in an individual whose body mass index is only just above the obesity threshold.

“This is important because the UK is experiencing an obesity epidemic characterised by children becoming obese at younger ages.”

The work was funded by an MRC New Investigator Research Grant and was carried out in partnership with University College London and the University of Cambridge.

The paper, Duration of obesity exposure between ages 10-40 years and its relationship with cardiometabolic disease risk factors: a cohort study, has been published in journal PLOS Medicine.


Notes for editors

Press release reference number: 20/202

Loughborough is one of the country’s leading universities, with an international reputation for research that matters, excellence in teaching, strong links with industry, and unrivalled achievement in sport and its underpinning academic disciplines.

It has been awarded five stars in the independent QS Stars university rating scheme, named the best university in the world for sports-related subjects in the 2020 QS World University Rankings and University of the Year by The Times and Sunday Times University Guide 2019.

Loughborough is in the top 10 of every national league table, being ranked 7th in the Guardian University League Table 2021, 5th in the Times and Sunday Times Good University Guide 2020 and 6th in The UK Complete University Guide 2021.

Loughborough is consistently ranked in the top twenty of UK universities in the Times Higher Education’s ‘table of tables’ and is in the top 10 in England for research intensity. In recognition of its contribution to the sector, Loughborough has been awarded seven Queen's Anniversary Prizes.

The Loughborough University London campus is based on the Queen Elizabeth Olympic Park and offers postgraduate and executive-level education, as well as research and enterprise opportunities. It is home to influential thought leaders, pioneering researchers and creative innovators who provide students with the highest quality of teaching and the very latest in modern thinking.