Riding the Weight Roller Coaster: How BMI Fluctuations Elevate Heart Health Risks

Variations in body weight could pose significant cardiovascular risks, according to a substantial study involving two separate cohorts including US veterans and UK participants. Researchers investigated the relationship between long-term variability in body mass index (BMI) and the risk of cardiovascular incidents. Their findings suggest that fluctuating weight is an independent risk factor for cardiovascular events, regardless of traditional risk factors. This connection persisted even when accounting for individuals' genetic predisposition to obesity.

The study intently focused on BMI; a common measure of obesity calculated by dividing a person's weight by the square of their height. It analyzed data from a period spanning 2011 to 2018 and included participants from the Million Veteran Program (MVP) and the UK Biobank (UKB). The participants, who initially had no cardiovascular disease (CVD) or cancer, were followed up for a median of 3.8 years.

The BMI variability was determined using standard deviation (SD) and coefficient of variation (CV), drawn from multiple clinical BMI measurements before the study's baseline. The researchers particularly concentrated on the incidence of composite CVD events such as nonfatal heart attack, acute ischemic stroke, and cardiovascular death. After adjustments for various CVD risk factors and statin use, the study concluded that BMI variability was consistently linked with an increased risk of CVD events across all major racial and ethnic groups in the MVP cohort, which primarily consisted of male US veterans. These findings were reinforced by similar observations in the UK cohort regarding cardiovascular death.

The connection between BMI variability and cardiovascular health has been a topic of debate, with inconsistent conclusions from past studies. However, the current study’s extensive database and advanced analytical methods provide new insights into the impacts of weight fluctuation. Suggested mechanisms behind these risks include metabolic and psychosocial factors associated with weight change, potentially leading to a rise in hunger and a decrease in satiety hormones, adipocyte hyperplasia, and accumulation of visceral fat, which all could stress the cardiovascular system.

Despite the considerable insights, the study did face certain limitations, such as an underrepresentation of female participants in the MVP cohort. Nonetheless, findings from the UK Biobank, which had a balanced sex distribution, supplemented the study's conclusions.

This study, detailed in JAMA Network Open in 2024 and freely accessible under the CC-BY License, prompts a closer look at weight fluctuation as a high-risk phenotype for cardiovascular diseases (CVD). It urges further research into the molecular pathways that could mediate this association and potentially offer new avenues for intervention.

Source Attribution: Zakaria Almuwaqqat, MD, MPH, and collaborators published the study findings in JAMA Network Open. Link to the original study.

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