Thirty years of data reveal changing heart health trends in obesity

by · News-Medical

Three decades of data from seven industrialized countries reveal that differences in blood pressure and cholesterol between older adults with obesity and those with normal BMI have narrowed, while younger adults with obesity continue to face elevated cardiometabolic risks.

Global trends in obesity and cardiovascular risk factors

Since the late 20th century, obesity rates have risen sharply worldwide, though not at the same pace everywhere. Obesity is a key cause of high blood pressure and abnormal cholesterol levels, especially higher non-high-density lipoprotein (HDL) cholesterol and lower HDL cholesterol. Blood pressure and non-HDL cholesterol mainly drive the risk of heart disease in obesity, while higher HDL is linked to a lower risk, though this link is not proven to be causal.

Previous studies have shown that blood pressure and cholesterol are influenced by factors beyond obesity alone. Lifestyle factors like smoking, alcohol, exercise, and diet also play major roles and can change even when obesity rates do not.

Recent changes in clinical guidelines have lowered treatment thresholds for blood pressure and cholesterol. More people, especially those with obesity, are now treated or given dietary advice, which helps narrow health differences between those with obesity and those with normal BMI. Yet, common risk factors such as eating more processed carbs may still worsen health for people with obesity and could widen these gaps.

Despite these shifts, there is still little comprehensive data on how blood pressure and cholesterol trends differ over time between people with obesity and those with normal BMI. This lack of data makes it harder to understand the changing impact of obesity and to set priorities for treating obesity, high blood pressure, and cholesterol disorders.

Seven-country study tracked cardiometabolic trends over three decades

Blood pressure and cholesterol were analyzed among adults with obesity, overweight, and normal BMI across seven industrialized countries in Asia, Europe, and North America. These included Japan, South Korea, Taiwan, Thailand, Finland, England, and the United States.

The analysis included 110 nationally representative studies from 1990 to 2024, covering 978,425 adults aged 20 to 79 with measured height, weight, and at least one blood pressure or cholesterol value. Each study year was divided into up to 24 groups by sex, age, and BMI.

Outcomes measured included systolic blood pressure (SBP), non-HDL and HDL cholesterol, and the use of antihypertensive and lipid-lowering medicines. Results are reported for adults classified by sex, age group, and BMI category: normal (20.0 to under 25.0), overweight (25.0 to under 30.0), class I obesity (30.0 to under 35.0), and class II/III obesity (35.0 and above).

Cardiometabolic risk gaps narrowed most in older adults

Researchers found that although obesity became more common in all seven countries over the study period, with the largest increases in the USA and the lowest prevalence remaining in Japan and South Korea, the relationship between obesity and several key cardiovascular risk factors changed substantially over time. In particular, differences in non-HDL cholesterol and systolic blood pressure (SBP) between BMI groups became smaller, especially among older adults.

Among people with normal BMI, non-HDL cholesterol declined in England, Finland, and the USA, and among older adults in South Korea and Taiwan. In contrast, younger and middle-aged adults in most Asian countries experienced little change. HDL cholesterol generally increased in people with normal BMI, remaining stable only in Taiwan and rising more modestly in Finland and the USA.

A similar pattern emerged for blood pressure. SBP fell in most countries, particularly among older adults, with the largest reductions seen in Japan, South Korea, and England. Thailand was the exception, where SBP increased over time. However, declines in both non-HDL cholesterol and SBP were generally greater among people with overweight or obesity than among those with normal BMI, resulting in a narrowing of differences between BMI groups.

This convergence was most pronounced among older adults and those with severe obesity. By the end of the study period, older adults with severe obesity in England and the USA had lower non-HDL cholesterol than their normal-BMI counterparts, a pattern that was also observed in some Asian countries, except among females in Taiwan. Among middle-aged adults, the gap also narrowed, particularly in the higher obesity classes, although obesity continued to be associated with higher non-HDL cholesterol. In younger adults, by contrast, these differences changed little and in some cases became larger.

HDL cholesterol followed a different trajectory. Across all age groups, people with overweight or obesity consistently had lower HDL cholesterol than those with normal BMI, and this gap generally widened over time because HDL cholesterol increased more among people with normal BMI. Differences in SBP also narrowed in most countries, although Taiwan again was an exception, where the gap widened despite larger declines among females. By 2022, older adults with overweight or obesity in the USA had lower SBP than those with normal BMI. Overall, the link between BMI and both cholesterol and blood pressure weakened in older adults but remained strong in younger adults.

The researchers also found that these changing risk-factor patterns coincided with an increase in the use of preventive medications. Cholesterol-lowering medicines, which were rarely used before 2000, became increasingly common among older adults, particularly in South Korea, Thailand, England, and the USA, while Taiwan consistently had the lowest treatment rates.

Use also increased among middle-aged adults in South Korea but remained uncommon in younger adults. Throughout the study period, older and middle-aged adults with overweight or obesity were more likely to receive lipid-lowering therapy than those with normal BMI, and this difference widened over time, especially in England, the USA, and Thailand.

A similar trend was observed for antihypertensive treatment. Use increased among older adults with normal BMI in several Asian countries, particularly Thailand and South Korea, but changed little in the USA and among most middle-aged adults. Across countries, however, antihypertensive medicines were used most frequently by older and middle-aged adults with overweight or obesity, especially older males in England and the USA, while treatment remained uncommon among younger adults regardless of BMI.

Cardiovascular risk gaps narrowed despite rising obesity rates

Obesity rates rose in all countries, but gaps in cholesterol and blood pressure between BMI groups narrowed over time, especially among older adults. The authors suggest that increased use of cholesterol- and blood pressure-lowering medicines may have been an important contributor to these improvements, while noting that lifestyle and dietary changes are also likely to have played a role.

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