Heart disease remains the leading cause of death in the United States, claiming one in five lives. Although conditions like high blood pressure, high cholesterol, diabetes, and obesity have long been recognized as major risk factors, recent research suggests there’s more to consider when assessing heart health. New findings indicate that the distribution of fat within the body, particularly within muscle tissue, could pose a greater risk to heart health than previously understood, even in those who appear to maintain a healthy weight.
Traditionally, doctors have relied on metrics like body mass index (BMI) to assess a person’s weight-related health risks. However, a groundbreaking study from Brigham and Women’s Hospital and Harvard Medical School sheds light on the importance of where fat is stored in the body, especially the presence of intramuscular fat fat deposited within the muscle tissue itself.
This study, published in the European Heart Journal, found that individuals with higher levels of intramuscular fat had a significantly higher risk of developing serious heart disease, regardless of their overall BMI or the amount of subcutaneous fat (fat beneath the skin) they carried. The researchers believe that intramuscular fat may impair heart function by contributing to microvascular dysfunction abnormal blood flow within the smallest blood vessels that supply the heart.
Dr. Cheng-Han Chen, an expert cardiologist who was not involved in the study, explained, “This observational study found an association between specifically the ‘intramuscular’ fat and increased risk of developing heart disease. This is the first large-scale study to compare different types of fat distribution in the body (intramuscular vs. subcutaneous) and provides insight into how we might better assess someone’s health status by their fat distribution.”
The research involved 669 participants, averaging 63 years of age, who were being evaluated for chest pain and shortness of breath caused by cardiac ischemia. The team used advanced imaging techniques, such as positron emission tomography (PET) scans and computed tomography (CT) scans, to measure both muscle and fat distribution in a specific section of the torso. This allowed the researchers to calculate the “fatty muscle fraction” the ratio of intramuscular fat to the total muscle and fat volume.
In the study’s follow-up period of around six years, those with more intramuscular fat were found to have a higher likelihood of developing coronary microvascular dysfunction (CMD), which is associated with an increased risk of heart disease and heart failure. Remarkably, even a slight increase in intramuscular fat just a 1% rise in the fatty muscle fraction correlated with a 2% increase in the risk of CMD and a 7% increase in the risk of future heart disease.
This study is pivotal in expanding our understanding of the relationship between fat and heart health. It challenges the traditional notion that heart disease risk is purely tied to excess weight or body fat in general. What matters, it seems, is not just how much fat one carries, but where it is stored.
As Dr. Viviany Taqueti, the lead author of the study, highlighted, “Knowing that intramuscular fat raises the risk of heart disease gives us another way to identify people who are at high risk, regardless of their body mass index.” This discovery could be particularly valuable in guiding medical professionals in assessing patients who may not appear overweight but carry hidden risks due to fat buildup in their muscles.
The findings also open the door to more precise ways of measuring fat distribution in the body. As Dr. Chen pointed out, there is currently no widely accepted method for easily quantifying intramuscular fat, but imaging technologies like CT scans hold promise for future advancements in this area.
As heart disease continues to be a major global health challenge, this study emphasizes the need for a more nuanced approach to understanding and preventing the disease. Identifying people at risk based on the distribution of fat, rather than relying solely on BMI or traditional risk factors, could lead to earlier interventions and more personalized treatments. In a world where both obesity and metabolic disorders are on the rise, it’s more important than ever to dig deeper into the factors that truly influence heart health and intramuscular fat could be one of the keys to unlocking that knowledge.
