Metabolic Syndrome Development During Aging with Special Reference to Obesity Without the Metabolic Syndrome

Obesity and its associated metabolic complications continue to increase worldwide. We investigated the development of metabolic syndrome (MetS) during aging in relation to body mass index (BMI) and exercise habits. We assigned special emphasis to the metabolic stability in individuals with obesity, but without MetS, a condition often referred to as metabolically healthy obesity.

Cross-sectional analysis was carried out in a sample of 19,129 men and women aged 45-75 years from the EpiHealth study. In addition, longitudinal analyses were carried out in the ULSAM study (2322 men at baseline followed from age 50 to age 77) and in the PIVUS study (1016 men and women at baseline followed from age 70 to age 80). Participants were categorized into six groups according to BMI category (normal weight/BMI <25 kg/m², overweight/BMI 25-30 kg/m², and obesity/BMI >30 kg/m²) and MetS status (+/-, National Cholesterol Education Program criteria).

MetS prevalence and number of MetS components increased with age in all three samples. The PIVUS study showed that high baseline BMI, low baseline physical activity, and increasing BMI during follow-up were related to increasing MetS prevalence and increasing numbers of MetS components during follow-up. One-third to half of individuals initially belonging to the obesity without MetS category acquired MetS during aging.

MetS prevalence increased during aging, especially in individuals with high BMI, low level of physical activity, and weight gain. Obesity without MetS was not a stable condition over time as many of those individuals gained metabolic disturbances during aging.