The OECD Health at a Glance 2025 report sends a clear signal: while countries have largely recovered from the acute shock of the covid pandemic, the underlying pressures on health systems remain unresolved. Health spending is high and rising, chronic conditions are increasingly common, and many governments are operating within tight fiscal constraints. In this context, a renewed focus on value-for-money is essential for achieving healthy populations and sustainable health systems.
Prevention delivers the greatest return on investment
Preventable conditions continue to account for a substantial share of premature mortality and long-term ill health across OECD countries. Diseases of the circulatory system (CVDs) and cancers remain the leading causes of death, while multimorbidity, also known as is now the norm among adults using primary care services. Among people aged 45 and over, more than four in five report living with at least one chronic condition.
Despite this, prevention remains persistently underfunded. In 2023, only 3% of total health spending was allocated to prevention and 14% to primary healthcare. These proportions have changed little over the past decade, with temporary increases during the pandemic proving short-lived. This is striking given the strong evidence that many preventive interventions are highly cost-effective and deliver long-term health and economic benefits.
Obesity as a central driver of health and system costs
Rising obesity rates illustrate the consequences of underinvestment in prevention. Across OECD countries, 54% of adults are living with overweight or obesity, and on average 19% are living with obesity. In more than four-fifths of OECD countries, obesity rates continue to increase. Among adolescents, 20% of 15-year-olds are already living with overweight or obesity, highlighting how early in life these risks emerge and how they track across the life course.
Addressing obesity represents one of the strongest value-for-money opportunities available to health systems. Effective obesity management helps prevent and reduce the burden of multiple non-communicable diseases, including cardiovascular diseases, diabetes, liver disease and several cancers. Importantly, it also improves quality of life and functional health for people living with obesity and related conditions, while reducing long-term demand on healthcare and social care services.
Yet investment in obesity prevention and clinical management remains modest relative to both the scale of the challenge and the potential returns.
Rebalancing spending towards disease prevention and primary care
Health spending already accounts for around 9.3% of GDP across OECD countries and approximately 15% of government expenditure. With ageing populations, technological advances and rising public expectations, further growth in spending is projected. However, higher expenditure alone does not guarantee better outcomes. Some countries achieve lower rates of avoidable mortality despite spending less than the OECD average, underlining the importance of how resources are used.
Improving value in national health systems will require a strategic shift towards interventions that deliver long-term health gains at relatively low cost. This includes strengthening prevention and primary care, which would include embedding obesity prevention and management across the life course, training and supporting multidisciplinary primary care teams, and making better use of digital health and innovative service delivery models. Attention to workforce sustainability, particularly nursing capacity and staff wellbeing, is also critical.
Invest now for sustainable health systems
The evidence is clear: sustainable health systems depend on long-term investment in prevention rather than short-term cost containment. Prioritising prevention and primary care — including evidence-based approaches to addressing obesity — offers one of the most effective ways to improve population health, reduce health inequalities and ensure better use of public resources.
The findings from OECD Health at a Glance 2025 reinforce a simple but powerful conclusion: value is achieved when health systems invest upstream, support people to live healthier lives, and address the root cause of chronic disease across the life course.
Read the full report: https://www.oecd.org/content/dam/oecd/en/publications/reports/2025/11/health-at-a-glance-2025_a894f72e/8f9e3f98-en.pdf
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