Public Release: 

Weight-loss surgery cuts risk of developing serious heart problems

New research finds long-term benefits for a range of health issues after surgery

London School of Hygiene & Tropical Medicine

Bariatric (weight-loss) surgery can reduce the risk of developing serious health conditions such as heart attacks and type 2 diabetes, as well improve existing conditions, according to a new study published in PLOS Medicine.

The project is the largest comprehensive study of longer-term outcomes post bariatric surgery in the UK. It suggests that widening the availability of bariatric surgery could boost the health prospects for thousands of people who are very obese (body mass index/BMI of 40 kg/m2 or more).

The research was led by the London School of Hygiene & Tropical Medicine in partnership with UCL and the UCLH Bariatric Centre for Weight Management and Metabolic Surgery.

Using primary care records, the researchers compared weight, BMI, and obesity-related illnesses between 3,882 bariatric surgery patients and similar control patients who did not have surgery, over an average period of three and a half years. They found that weight-loss surgery can significantly improve existing type 2 diabetes and reduce abnormally high blood pressure.

They also applied the findings to estimate that if the 1.4 million people believed to be morbidly obese in the UK had bariatric surgery, it could prevent 80,000 cases of hypertension, 40,000 cases of type 2 diabetes, and 5,000 heart attacks over a four year period. Furthermore, 110,000 people with type 2 diabetes and 13,000 people with hypertension could significantly improve their condition.

Additionally, the study confirmed that the procedures stimulate dramatic and substantial weight loss which is sustained for at least four years, and suggested that gastric bypass and sleeve gastrectomy promote the most weight loss out of the different types of surgery.

Bariatric surgery is used to treat people who are very obese¹, for example, a woman of average height (162cm, 5 feet 5 inches), with type-2 diabetes and weighing 96 kg/15 stone, which equates to a BMI of 35. It is available on the NHS to treat people when other options, such as lifestyle changes, have not been successful.

Lead author Dr Ian Douglas, from the London School of Hygiene & Tropical Medicine, said: "Obesity is one of the biggest health problems of our generation. Rates of cardiovascular disease, although slowly declining, are still alarmingly high while type 2 diabetes is on the rise, affecting 3.5 million people in Britain. Finding effective ways to tackle the obesity crisis is therefore a key public health strategy.

"Whilst effective prevention is clearly needed, our findings show that as well as helping patients substantially lose weight, bariatric surgery improves serious obesity-related illnesses as well as reducing the risk of developing them. People having weight-loss surgery were 70% less likely to have a heart attack, and those with type 2 diabetes were nine times more likely to see major improvements in their diabetes. We also found positive effects on angina and the debilitating condition obstructive sleep apnoea."

The study also indicated which type of surgery might be most effective for losing weight. Estimated average four year weight loss was 38 kg/six stone for gastric bypass, 31 kg/five stone for sleeve gastrectomy, and 20 kg/three stone for gastric band.

Study co-author Professor Rachel Batterham, Head of the UCLH Bariatric Centre for Weight Management and Metabolic Surgery and the UCL Centre for Obesity Research, said: "Bariatric surgery is safe and produces unrivalled health benefits that are life-changing for patients and cost-saving for the NHS. Unfortunately, less than 1% of the patients who could benefit from this surgery currently receive surgery. This represents a major missed opportunity in terms of improving health and economic savings. Action is now needed to remedy this situation."

The researchers note that the accuracy of these findings may be limited by the incomplete recording of some outcomes in primary care patient management records. They were also unable to look in detail at short-term adverse outcomes associated with bariatric surgery, but noted that nationally collected data suggests such complications are rare.


For more information or to request interviews contact the London School of Hygiene & Tropical Medicine press office on or +44(0)2079272802.

Notes for Editors

* Ian J. Douglas, Krishnan Bhaskaran, Rachel L. Batterham, Liam Smeeth. Bariatric Surgery in the United Kingdom: A Cohort Study of Weight Loss and Clinical Outcomes in Routine Clinical Care. PLOS Medicine. doi:10.1371/journal.pmed.1001925

* The study was supported by the National Institute for Health Research University College London Hospitals Biomedical Research Centre, Medical Research Council, Wellcome Trust, Rosetrees Trust and The Stoneygate Trust.

* This article presents independent research funded by NIHR and other funders. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.

* ¹ A male example would be an average height man of 5 feet 9 inches (or 175 cm), with type 2 diabetes and weighing just over 17 stone or 110 kg.

* Notably, only 5,558 bariatric procedures were done in the UK in 2013, compared with 37,300 in France, where the prevalence of obesity is lower than the UK. Similarly, whilst 154,276 bariatric procedures were performed in the USA and Canada in 2013, an estimated 6.4% of the adult US population has a BMI>40 kg/m2, equating to around 14 million people, many of whom could likely benefit from surgery.

About the London School of Hygiene & Tropical Medicine

The London School of Hygiene & Tropical Medicine is a world-leading centre for research and postgraduate education in public and global health, with 3,900 students and more than 1,000 staff working in over 100 countries. The School is one of the highest-rated research institutions in the UK, and among the world's leading schools in public and global health. Our mission is to improve health and health equity in the UK and worldwide; working in partnership to achieve excellence in public and global health research, education and translation of knowledge into policy and practice.

About UCLH

UCLH (University College London Hospitals NHS Foundation Trust), situated in the West End of London, is one of the largest NHS trusts in the United Kingdom and provides first-class acute and specialist services. The state-of-the-art University College Hospital which opened in 2005, is the focal point of UCLH alongside four cutting-edge specialist hospitals. UCLH is committed to research and development and forms part of UCL Partners which in March 2009 was officially designated as one of the UK's first academic health science centres by the Department of Health. UCLH works closely with UCL, translating research into treatments for patients. Visit our website, we are also on Facebook (UCLHNHS), Twitter (@UCLH) and Youtube (UCLHvideo).

About the NIHR University College London Hospitals Biomedical Research Centre

The National Institute for Health Research (NIHR) is funded by the Department of Health to improve the health and wealth of the nation through research. Since its establishment in April 2006, the NIHR has transformed research in the NHS. It has increased the volume of applied health research for the benefit of patients and the public, driven faster translation of basic science discoveries into tangible benefits for patients and the economy, and developed and supported the people who conduct and contribute to applied health research. The NIHR plays a key role in the Government's strategy for economic growth, attracting investment by the life-sciences industries through its world-class infrastructure for health research. Together, the NIHR people, programmes, centres of excellence and systems represent the most integrated health research system in the world. For further information, visit the NIHR website (

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