Why fat under the 'happiness curve' is a danger to heart health

A new study published in the Journal of the American College of Cardiology has highlighted the dangers of abdominal fat, known as visceral fat, which lies beneath the so-called “curve of happiness.” This type of fat, which accumulates around internal organs, poses a greater risk to heart health than previously understood. Researchers analyzed data from nearly 260,000 individuals over a period of approximately two decades, revealing that relying solely on body mass index (BMI) to assess obesity and related risks can lead to misclassification. The traditional BMI measurement, which compares weight to height, has long been used to determine whether someone is underweight, overweight, or obese. However, this method fails to account for how fat is distributed within the body. The latest research shows that measuring waist circumference or using the waist-to-hip ratio provides more accurate insights into cardiovascular risk. For example, individuals with a normal BMI but high waist measurements were found to have up to a 50% increased risk of cardiovascular events compared to those with normal measurements. Among the findings, researchers identified that 5% of individuals classified as having a normal BMI had elevated waist circumferences, while 18% exhibited a high waist-to-hip ratio, indicating hidden abdominal obesity. These individuals were categorized as “false healthy” due to their misleading BMI readings. On the other hand, 45% of those diagnosed with obesity had a low waist-to-hip ratio, suggesting they carried more peripheral fat rather than visceral fat. This group was associated with significantly lower cardiovascular risk than predicted based on their weight alone. The composition of body fat plays a crucial role in determining health outcomes. Central adiposity, particularly visceral fat, has been linked to a range of serious conditions, including heart failure and atrial fibrillation. In participants with obesity, visceral fat accounted for up to 49% of cases of heart failure and nearly half of instances of atrial fibrillation. This underscores the importance of understanding not just how much fat a person carries, but where it is located. Dr. Diego Bellido, president of the Spanish Society of Obesity (SEEDO), emphasized the need for a more comprehensive approach to assessing obesity and its health implications. He stated that measuring waist circumference is cost-effective, quick, and feasible in primary care settings. While he acknowledged the value of BMI, he stressed that it should be supplemented with additional metrics such as waist size. “We shouldn’t abandon BMI,” he explained, “but we must pay closer attention to where fat is stored.” This discussion aligns with broader efforts in medical science to refine diagnostic criteria for metabolic diseases. A special issue of The Lancet last year explored the need for updated guidelines to better understand the pathophysiology of chronic metabolic disorders. Despite claims that BMI might be obsolete, Dr. Andreea Ciudin, an endocrinologist at the Vall d’Hebron University Hospital, argued that both BMI and waist measurements remain valuable tools. She noted that measuring waist circumference is inexpensive and just as efficient as calculating BMI. “Using both methods offers practical advantages,” she added, highlighting the importance of integrating multiple indicators for a more complete assessment of health risks.