Despite growing consensus that obesity is a chronic, multifactorial disease, millions of people remain undiagnosed until serious health complications emerge.1
Findings from the AstraZeneca-sponsored CALOR real-world evidence study suggest that underdiagnosis and late recognition of obesity may contribute to a growing global burden of interrelated cardiometabolic and renal disease, and that type 2 diabetes increases the risk of comorbidities such as heart failure and chronic kidney disease.2,3
Obesity is more than a number on the scale
Obesity is a known driver of complications across the cardiovascular, renal and metabolic (CVRM) continuum.4 Yet despite progress in treatment and awareness, its true burden often remains hidden in plain sight.1
Social, environmental and biological factors converge to create a complex, multifactorial disease that extends far beyond weight alone.4 New data from the CALOR observational study programme reveal that a large proportion of people living with obesity or overweight are not formally recognised within the healthcare system, delaying opportunities for intervention and prevention.2
Too many people living with obesity are still being recognised far too late, often only after serious health complications have set in. This delayed recognition represents missed opportunities—not just for individuals, but for health systems.
The CALOR observational study has analysed real-world data from more than eight million people living with obesity or overweight across the US and Japan, with insights from two datasets presented:
- An analysis of ~7 million people in the US and ~1.2 million in Japan explored how frequently heart and kidney disease comorbidities occur in those living with overweight or obesity and how the presence of type 2 diabetes further increases these risks.3
- A second analysis focussed on people with an elevated body mass index (BMI)—≥30 kg/m² for the US study population and ≥25 kg/m² for the Japan population—to understand the differences in comorbidities and complications between those who have and have not received an obesity diagnosis. The cohorts included ~3.6 million people in the US and ~3.1 million people in Japan.2
The hidden majority: underdiagnosis and its impact
The findings from CALOR are striking. Of the ~3.6 million people in the US studied in the second analysis, around 30% of people who met the body mass index (BMI) criteria for obesity (≥30 kg/m²) didn’t have a recorded obesity diagnosis, despite established clinical pathways and the availability of effective treatments.4 In Japan, where formal recognition of obesity has historically been limited, only 2.3% of the ~3.1 million people included in the study had a recorded obesity diagnosis.2
Underdiagnosis matters. Without a formal diagnosis, people are less likely to receive guideline-based care, referrals, or support to manage the physical and psychological impact of obesity. The absence of a clinical diagnosis reinforces barriers to care and delays access to the integrated, long-term support that obesity demands.5
These data expose a global pattern. Even in healthcare systems that differ in structure and culture, obesity is often under-recognised meaning that people are being diagnosed too late—often when comorbidities are already established.
The weight of comorbidity: diagnosed late, complicated early
Beyond underdiagnosis, the CALOR programme highlights the extensive cardiorenal-metabolic burden faced by people living with obesity or overweight. Across the two CALOR analyses, the prevalence of comorbidities such as hypertension, dyslipidaemia, chronic kidney disease (CKD) and heart failure (HF) was high across all groups, and further elevated in people who were also living with type 2 diabetes.2,3
Data show that in the US, 87% of people with obesity or overweight had at least one cardiorenal comorbidity, rising to 99% in people who also had type 2 diabetes. In Japan, comorbidity prevalence was also high—64% of people with obesity or overweight had at least one cardiorenal comorbidity—which was even higher among those with type 2 diabetes (prevalence increased to 82%).3 The results underscore that obesity and overweight are central to cardiorenal diseases, and living with type 2 diabetes may further amplify the risk of having heart and kidney conditions:3
The data show that when obesity and type 2 diabetes coexist, the risk of cardiovascular and renal complications rises sharply. This underscores the need to move beyond treating these conditions in isolation and to recognise their shared biological and clinical pathways.
Furthermore, the analysis showed that among people with a recorded obesity diagnosis, occurrence of complications and comorbidities were higher compared to those without a diagnosis across both the US and Japan—underscoring how most individuals were already managing multiple conditions by the time obesity was formally recognised.2
Obesity and type 2 diabetes are deeply interconnected, driving overlapping cardiovascular, renal and metabolic risks. As their prevalence continues to rise, healthcare systems must evolve from fragmented, single-disease management to integrated, multi-specialty models that address shared risks earlier in collaboration with primary care. Real-world evidence from studies like CALOR strengthens the case for this shift — showing the broader impact of delayed recognition and why cardio-renal-metabolic protection must guide policy, guidelines and care delivery.
If we don’t act now, by 2045 approximately 12% of the global population will be living with type 2 diabetes and 22% with obesity.6
CALOR: guiding the path forward
The CALOR programme represents a cornerstone of AstraZeneca’s commitment to advancing understanding of obesity through real-world evidence. By analysing millions of patient records across diverse healthcare systems, CALOR provides new insight into diagnostic trends, comorbidity overlaps, and the complex interplay between obesity, diabetes and other CVRM diseases.
Many national approaches to patient care remain siloed, with obesity prevention plans separated from strategies for managing interrelated CVRM conditions.7 The insights from CALOR reinforce the need to develop person-centred models of care, update clinical guidelines, align reimbursement frameworks and equip healthcare providers with the training to deliver holistic obesity management.
Ultimately, the findings underscore the need to combine national non-communicable disease (NCD) strategies that address both prevention and management, to reframe obesity management as part of a holistic, continuous approach to CVRM health rather than a singular focus on weight loss.
The CALOR findings reinforce a clear message: if obesity is diagnosed late, interrelated health complications will have already advanced. Earlier recognition can change outcomes—enabling timely intervention, coordinated care and lasting impact.2
By translating real-world insights into scientific and clinical innovation, AstraZeneca is helping to shift obesity care from reaction to prevention.
Real-world insights are not just data points—they’re the stories of people who could have been identified sooner. If we act on this knowledge, we can change the trajectory of obesity.
Our ambition is clear: to lead a new era of obesity care and weight management, with integrated solutions and sustainable progress across the CVRM spectrum.
You may also like
References
- Kapoor A, et al. Weighing the odds: Assessing underdiagnosis of adult obesity via electronic medical record problem list omissions. Digital Health. 2020 Jan;6:205520762091871.
- Horn DB et al. Trends in Diagnosing Obesity (the CALOR study). Presented at ObesityWeek 2025; 04–07 November 2025, Atlanta, USA.
- Waki H, et al. Type 2 diabetes associates with higher occurrence of cardiorenal comorbidities in people living with overweight or obesity (the CALOR study). Presented at European Association for the Study of Diabetes (EASD) Congress; 15–19 September 2025, Vienna, Austria.
- Cornier MA. A review of current guidelines for the treatment of obesity. Am J Manag Care. 2022 Dec;28:(15 Suppl):S288-S296.
- Daley SF, et al. Overcoming Stigma and Bias in Obesity Management [Internet]. PubMed. Treasure Island (FL): StatPearls Publishing; 2025. Available from: http://www.ncbi.nlm.nih.gov/books/NBK578197 (Accessed: October 2025)
- Irish Heart Foundation. Almost a quarter of the world will be obese by 2045 [Internet]. Irish Heart. 2018 [cited 2025 Oct 22]. Available from: http://irishheart.ie/news/almost-a-quarter-of-people-will-be-obese-by-2045/. (Accessed: October 2025)
- Al-Chalabi S, et al. Shifting the silos: transforming care for cardiorenal metabolic disease [Internet]. Manchester.ac.uk. 2025. Available from: http://blog.policy.manchester.ac.uk/posts/2025/05/shifting-the-silos-transforming-care-for-cardiorenal-metabolic-disease/ (Accessed: October 2025)
Veeva ID: Z4-78119
Date of preparation: November 2025