Thirty years of data from seven developed countries show that while the differences in blood pressure and cholesterol between older adults with obesity and those with a normal BMI are narrowing, younger people with obesity continue to face increased cardiometabolic risks.
Study: Metabolic characteristics of obesity and normal BMI in developed countries: a multi-country analysis of national population-based studies. Image credit: Victor Moussa/Shutterstock.com
In recent research, lancet They compared blood pressure, cholesterol levels, and use of antihypertensive and lipid-lowering drugs between obese and normal BMI people in developed countries.
Global trends in obesity and cardiovascular risk factors
Obesity rates have risen sharply around the world since the late 20th century, but not at the same pace everywhere. Obesity is a major cause of high blood pressure and abnormal cholesterol levels, especially elevated non-high-density lipoprotein (HDL) cholesterol and reduced HDL cholesterol. The risk of heart disease in obesity is primarily driven by blood pressure and non-HDL cholesterol, with higher HDL levels associated with lower risk, but this association has not been proven to be causal.
Previous research has shown that blood pressure and cholesterol are influenced by factors beyond obesity. Lifestyle factors such as smoking, alcohol, exercise, and diet also play a large role and can change obesity rates even if they remain the same.
Recent changes in clinical guidelines have lowered treatment thresholds for blood pressure and cholesterol. More people, especially obese people, are now receiving treatment and dietary advice, which is helping to narrow the gap in health status between obese people and people with a normal BMI. However, common risk factors such as higher intake of processed carbohydrates may still worsen the health of obese people, potentially widening these gaps further.
Despite these changes, there is still little comprehensive data on how blood pressure and cholesterol trends differ over time between obese people and people with a normal BMI. This lack of data makes it difficult to understand the changing effects of obesity and to prioritize treatment of obesity, hypertension, and cholesterol disorders.
Study in seven countries tracked cardiometabolic trends over 30 years
Blood pressure and cholesterol were analyzed in obese, overweight, and normal BMI adults from seven developed countries in Asia, Europe, and North America. These include Japan, South Korea, Taiwan, Thailand, Finland, the United Kingdom, and the United States.
The analysis included 110 nationally representative studies from 1990 to 2024 that included 978,425 adults aged 20 to 79 who had height, weight, and at least one blood pressure or cholesterol level measured. Each study year was divided into up to 24 groups by gender, age, and BMI.
Outcomes measured included systolic blood pressure (SBP), non-HDL and HDL cholesterol, and antihypertensive and lipid-lowering drug use. Results for adults are reported by sex, age group, and BMI category, categorized as normal (20.0 to less than 25.0), overweight (25.0 to less than 30.0), class I obesity (30.0 to less than 35.0), and class II/III obesity (35.0 or more).
The cardiometabolic risk gap narrows the most in older people
The researchers found that the relationship between obesity and several important cardiovascular risk factors changed significantly over time, although obesity became more common in all seven countries during the study period, with the largest increase in the United States and the lowest prevalence remaining in Japan and South Korea. Notably, the differences in non-HDL cholesterol and systolic blood pressure (SBP) between BMI groups were smaller, especially among older adults.
Among people with normal BMI, non-HDL cholesterol decreased in the UK, Finland and the US, and in older adults in South Korea and Taiwan. In contrast, in most Asian countries there was little change in young and middle-aged populations. HDL cholesterol generally increased in people with normal BMI, but remained stable only in Taiwan and increased more modestly in Finland and the United States.
A similar pattern appeared for blood pressure. SBP declined in most countries, especially among older people, with the largest declines seen in Japan, South Korea, and the United Kingdom. Thailand is an exception, with SBP increasing over time. However, reductions in both non-HDL cholesterol and SBP were generally greater in those with overweight or obesity than in those with normal BMI, resulting in a narrowing of the differences between BMI groups.
This convergence was most pronounced among older adults and those with severe obesity. By the end of the study period, severely obese older adults in the UK and US had lower non-HDL cholesterol than older adults with a normal BMI. This pattern was also observed in some Asian countries, except for women in Taiwan. Among middle-aged adults, obesity remained associated with higher non-HDL cholesterol, although the gap narrowed, especially among those with high obesity levels. In contrast, in young adults, these differences remained largely unchanged and in some cases became larger.
HDL cholesterol followed a different trajectory. Across all age groups, overweight or obese people consistently had lower HDL cholesterol than people with a normal BMI, and this difference generally widened over time, as people with a normal BMI had more HDL cholesterol. The SBP gap also narrowed in most countries, with the exception of Taiwan, where the gap widened despite a larger decline for women. By 2022, overweight or obese older adults in the United States will have lower SBP than older adults with normal BMI. Overall, the associations between BMI and both cholesterol and blood pressure are weaker in older adults but remain strong in younger adults.
The researchers also found that changing patterns of these risk factors coincided with increased use of preventive drugs. Cholesterol-lowering drugs, which were rarely used before 2000, have become increasingly common among older adults, particularly in South Korea, Thailand, the United Kingdom, and the United States, while treatment rates in Taiwan have consistently been the lowest.
Use also increased among middle-aged adults in South Korea, but remained rare among younger people. Over the study period, older and middle-aged adults with overweight or obesity were more likely to receive lipid-lowering therapy than adults with normal BMI, and this difference widened over time, particularly in the United Kingdom, United States, and Thailand.
A similar trend was observed with antihypertensive treatment. Use increased among older adults with normal BMI in some Asian countries, particularly Thailand and South Korea, but there was little change in the United States and among most middle-aged adults. However, across countries, antihypertensive drugs were most frequently used in older and middle-aged adults who were overweight or obese, especially older men in the United Kingdom and United States, while treatment remained uncommon in younger people regardless of BMI.
Cardiovascular risk gap narrows despite rising obesity rates
Obesity rates rose in all countries, but differences in cholesterol and blood pressure between BMI groups narrowed over time, especially among older people. The authors suggest that increased use of cholesterol- and blood-pressure-lowering drugs may have made an important contribution to these improvements, but note that changes in lifestyle and diet are also likely to play a role.
However, HDL cholesterol remains variable and low among obese individuals, and increasingly so, and differences in cardiometabolic risk persist, particularly among obese young adults who receive little treatment regardless of BMI, highlighting the need for continued public health efforts focused on early prevention, screening, and, when appropriate, treatment.
Download your PDF copy now.
