Proving what works: how evaluation shaped a national programme

The prevalence of obesity in England has doubled in 30 years. Today, 15 million adults – 29% of the population – are living with obesity, the single largest contributor to avoidable ill health in the country. It drives premature death and a cascade of conditions: heart disease, Type 2 diabetes, cancer, musculoskeletal problems, poor mental health. The annual cost to the NHS and social care is estimated at £13.8 billion, with a further £31 billion lost in economic productivity.

Structured weight management programmes work better than advice alone. But treatment needs to reach people at scale, and despite clinical guidelines recommending brief opportunistic interventions in primary care, these remain the exception rather than the norm.

Our approach

In 2021, the Department of Health and Social Care invested in a national enhanced service (NES) – a £7.2 million annual financial incentive for clinicians to raise weight management in consultations – alongside a new digital weight management programme (DWMP) for people with diabetes or hypertension. Given the scale of investment and national rollout, rigorous evaluation was essential.

Our team at the University of Oxford partnered with Newcastle University and NHS England analysts to deliver a comprehensive assessment of referral patterns, patient and practitioner experiences, economic impact, and long-term population health benefits. Working directly with policy implementers from the outset ensured findings could inform decisions as they were being made – not afterwards.

What we found – and why it matters

The evaluation revealed significant results:

1. Referrals transformed. The NES increased weight management referrals four-fold across England.
2. Meaningful weight loss achieved. People completing the digital programme lost an average of 3.68kg (men) and 3.17kg (women). Our modelling estimates that for every 10,000 people completing the programme, this would prevent 275 cases of Type 2 diabetes in men and 210 in women, along with significant reductions in heart disease.
3. Equitable reach demonstrated. One third of participants came from ethnic minority backgrounds. A bespoke triage system allocated people from more deprived areas to higher levels of coaching support – and it worked. Weight loss outcomes did not depend on socioeconomic status or sex.
4. Highly cost-effective. Economic modelling showed a cost of £4,202 per quality-adjusted life year (QALY) – a measure combining length and quality of life – delivering significant returns through prevented illness and reduced NHS costs.

These findings directly influenced national policy. The 10 Year Health Plan for England, announced in July 2025, committed to doubling referrals to the NHS digital weight management programme – reaching 125,000 more people every year. Our evidence was used to make the case for continuing the NES financial incentive at £7.2 million in both 2024/25 and 2025/26.

What this means

This research demonstrates a rare achievement in applied health research: a direct line from evaluation to national policy change. By proving the combined approach works, is cost-effective, and reaches diverse communities equitably, this evaluation secured continued investment and expansion that will benefit millions of people across England.

What needs to happen next

A key finding is that only half of patients referred to the programme took it up – both a challenge and an opportunity, since improving uptake would amplify the health benefits considerably. Further research is needed to understand barriers to engagement and optimise the programme's reach.

The team continues to advise NHS England through the Weight Management Advisory Group, and findings are being shared with NICE to inform future clinical guidelines.

Lessons for future research

This was a complex programme – six work packages, 26 researchers across two universities, and stakeholders spanning NHS England and the DHSC. The overriding lesson is that successful policy evaluation demands exceptional collaboration, not just good research.

Working with policy implementers from the start meant research questions addressed real-world priorities and evidence arrived when decisions were being made. Regular updates on how the digital programme was performing proved vital for refining it during implementation.

For researchers undertaking similar work, the team recommends:

• Establishing clear governance structures early, with flexibility built in to accommodate policy changes
• Securing early access to administrative data systems
• Engaging stakeholders beyond formal meetings – monthly check-ins and informal conversations kept teams connected, particularly when colleagues moved roles
• Aligning evaluation timelines with policy decision-making cycles
• Combining quantitative outcomes with qualitative insights from patients and practitioners to build a comprehensive evidence base