The rising challenge of severe obesity

Video: Jonathan Pinkney, Dawn Swancutt, Mark Tarrant & Steve Perry

Overweight and obesity now affect two thirds of adults (over 30 million people) in the UK. Obesity increases the risk of cardiovascular and kidney diseases, diabetes, cancer, and musculoskeletal disorders. Severe obesity (often defined as Body Mass Index > 40 kg/m2, or BMI > 35 kg/m2 if accompanied by comorbidity) is also increasingly common. About 7-9% of adults have BMI>35, and 3-5% of middle-aged adults have BMI>40 kg/m2. There are also significant gender and ethnic variations. Once relatively rare, severe obesity now affects millions of people and has become a common reason for medical referral. People with severe obesity report impaired quality of life, including physical, social, and economic impacts, as well as compromised life expectancy. People with severe obesity also experience a higher likelihood of psychological disorders, such as depression and anxiety which themselves can be exacerbated by societal experiences such as weight sigma.

A principal challenge for health services is that, with the specific exception of bariatric surgery, the optimum long-term management of severe obesity, and its effectiveness are poorly defined.

Current weight management services

In the UK, resources for prevention and treatment of overweight and obesity are categorised into four “tiers”. Tier 1 represents non-medical community-based resources; Tier 2 includes primary care-based resources and treatment programmes; Tier 3 services, the focus of our programme of research, are specialist multidisciplinary services designed for assessment and treatment of patients with severe obesity who have not responded well to earlier interventions; Tier 4 services include bariatric surgical units.

Although NICE has advocated the principles of multidisciplinary, personalised behavioural intervention for Tier 3 clinics, the optimum design and delivery of such interventions is poorly researched.

Group-based behavioural intervention in Tier 3 services?

Tier 3 services face several major challenges. On the one hand there are rising numbers of referrals and limited resources, and on the other hand the evidence base necessary for effective Tier 3 programmes is lacking. Therefore, rational commissioning decisions are problematic, and commissioners and providers need quality information to structure and deliver interventions. Furthermore, rising demand makes delivery of behavioural intervention to patients on a one-to-one, individual basis, increasingly unfeasible. One solution might be to deliver care to groups of patients simultaneously, in groups, but how best to do this in a way which meets NICE guidelines is unclear.

There is already fairly widespread use of some group activities in Tier 3 services, mainly for information giving and educational purposes. Wholescale use of groups as the core programme of behavioural intervention in Tier 3 services is rare. The optimum design, delivery and effectiveness of group-based behavioural intervention programmes in Tier 3 is poorly understood.

Aim of the research

The aim is to establish best practice for group-based treatment in Tier 3 weight management and to test whether the PROGROUP intervention is feasible to deliver, effective and cost-effective as an NHS programme.

Design and methods

The feasibility trial

Initially we ran four test groups to establish if PROGROUP would work on a larger scale. We recruited and randomly allocate patients to receive either PROGROUP or the treatment that is normally offered to patients within their Tier 3 service. This stage included up to 100 patients recruited from three Tier 3 services. If this stage was successful, we would move to a large trial in the final stage of the research.

The main trial

This large-scale study will take place in approximately 8 centres around the UK and involve up to 1,000 patients. As in the feasibility trial, patients will receive either PROGROUP or usual care. This will be decided by a computer. After 12 months we will assess each participant’s weight and determine whether the PROGROUP intervention improves patients’ health. We will also assess whether the intervention is cost-effective for the NHS.


The findings from the project will be shared regionally, nationally and internationally with the help of our patient consultation group. We will do this through weight management services we have worked with and with the help of our many stakeholders, including the Association for the Study of Obesity, British Dietetic Association, commissioners and NHS England. The findings will also be shared publicly through press releases, newsletters, social media and in academic journals.

Project activity

Working with a national team of specialist service providers, service users, Tier 3 commissioners, dieticians, psychological, behaviour change and implementation science experts we have devised a proposal to optimise how a group-based service for people with severe obesity may be developed and used. The project comprises three work packages.

A patient advisory group and an implementation advisory group was set up. These groups met virtually during the Covid-19 pandemic and also provided feedback to the research team on an individual basis. Both groups have been invaluable in providing feedback on the project plans and materials.

This project is funded by the National Institute for Health and Care Research (NIHR) [PROGROUP (NIHR201038)] and in conjunction with the Applied Research Collaboration South West Peninsula [PenARC (NIHR200167)]. The views expressed are those of the author(s) and not necessarily those of the NIHR or the Department of Health and Social Care.

We are grateful for the support from the research Sponsor for this study, University Hospitals Plymouth NHS Trust, and our public and patient advisory group for their input in developing this research.