Low and high body mass index (BMI) are related to higher physiological age

Weighing the Years: The Convergence of Obesity, Metabolic Syndrome, and Aging
Obesity, with a body mass index (BMI) over 30 kg/m², often occurs alongside conditions like hypertension and high blood sugar, known as metabolic syndrome. Aging naturally leads to declining health, but chronological age doesn’t fully reflect this. To quantify this variability, indices such as the frailty index (FI) and the functional aging index (FAI) have been developed. While FI assesses the cumulative burden of health deficits, FAI evaluates current functional capabilities, offering a dynamic perspective on health status.

Obesity and aging share common pathophysiological features, including chronic inflammation and metabolic dysregulation. Obesity and metabolic syndrome can also speed up aging, increasing the risk of frailty and suggesting a connection between higher body weight and faster aging. However, the interplay between these factors and their collective influence on physiological aging remains underexplored. Thus, this study aimed to investigate the joint association of BMI and metabolic syndrome with physiological aging, as measured by FI and FAI, and to determine how these relationships evolve with advancing chronological age.

Photographer Name: Mr. BARATTINI STEFANO of MILAN

To examine this, longitudinal data from 1,789 Swedish twins aged 50+ years were used from three NEAR population studies: the Swedish Adoption/Twin Study of Aging (SATSA), a Longitudinal Study of Gender Differences in Health Behavior and Health among Elderly (GENDER), and the Origins of Variance in the Oldest-Old: Octogenarian Twins (OCTO-Twin).

Low and high body mass index (BMI) are related to higher physiological age
The study found that BMI, health conditions related to metabolic syndrome, and chronological age all work together in complex ways to affect our physiological age. A pattern was found where people with a BMI between 26-28 kg/m² generally had a lower physiological age, compared to those with a lower or higher BMI. Also, having metabolic syndrome, which includes issues like high blood pressure and sugar, usually makes people have a higher physiological age. For persons between 65 and 85 years, if they had metabolic syndrome, the effect of a higher BMI making them seem older was even stronger. The findings underscore that both low and high BMI, along with metabolic syndrome, are associated with an advanced physiological age, potentially accelerating the aging process. This study illuminates the multifaceted nature of aging, highlighting the significant roles of genetic and environmental factors in shaping our physiological journey through life.

Peggy Ler, first author of the study. Photo: Gunilla Sonnebring.

Publication
Ler P, Ploner A, Finkel D, Reynolds C A, Zhan Y, Jylhävä J, Dahl Aslan AK, Karlsson IK. Interplay of body mass index and metabolic syndrome: association with physiological age from midlife to late-life. GeroScience. 2024: 46:2605–2617. https://doi.org/10.1007/s11357-023-01032-9.