The link between obesity and heart health

At the recent Blackburn Course in Obesity Medicine, hosted by Harvard Medical School, Dr Harold Bays, Medical Director at the Louisville Metabolic and Atherosclerosis Research Center, highlighted the direct and indirect ways in which obesity increases the risk of cardiovascular disease.

“Obesity both directly and indirectly contributes to heart disease,” said Dr Bays. “It’s not just a comorbidity. Increased fat mass is meaningfully linked to cardiovascular disease.”

Research published in the European Journal of Preventive Cardiology supports this view, showing that adipose tissue – particularly the visceral fat around the abdomen – is metabolically active and plays an endocrine and immune role. It releases hormones and other substances that impair the cardiovascular system’s function. This fat isn’t limited to the abdomen, as fat deposits around the heart can cause inflammation, affect blood vessels and impair their ability to dilate and relax. The result is higher blood pressure, increased inflammation and a greater likelihood of cholesterol plaque formation, known as dyslipidaemia.

Cardiologist Dr Minisha Kochar of National Jewish Health in Denver explained that when vessel walls are damaged by inflammation, elevated blood sugar or hypertension, it becomes easier for cholesterol to build up, leading to atherosclerosis. “These processes are closely tied to how excess adiposity works in the body,” she said.

Obesity also increases the likelihood of developing metabolic syndrome, a cluster of conditions that significantly raise cardiovascular risk. These include abdominal obesity, high blood pressure, high blood sugar, elevated triglycerides and low levels of HDL (“good”) cholesterol. “Dyslipidaemia and in particular low HDL and high triglycerides, leads to insulin resistance, which can ultimately cause type 2 diabetes,” added Dr Kochar.

In addition to these direct effects, obesity influences cardiovascular health in more indirect ways. One is sleep disruption, particularly obstructive sleep apnoea. This condition, often caused or worsened by excess weight, affects breathing during sleep and alters hormone regulation. It can drive food cravings, increase calorie intake and ultimately worsen weight gain. The cycle is bidirectional, according to Dr Kochar, with poor sleep contributing to obesity and obesity making sleep problems worse. Research shows that a 10 per cent weight gain can increase the risk of sleep apnoea sixfold.

Another major indirect link is insulin resistance. As obesity develops, so does resistance to insulin, leading to type 2 diabetes – a significant risk factor for heart disease. The American Heart Association reports that people living with type 2 diabetes are more likely to suffer heart attacks, strokes and heart failure than those without diabetes.

Despite the risks, there is good news. Dr Bays emphasised that even modest weight loss can improve cardiovascular function. “Even before substantial weight reduction, you see benefits such as reduced blood pressure, improved insulin sensitivity, reduced inflammation and better endothelial function,” he said.

Dr Kochar added that lifestyle changes are crucial, including a heart-healthy diet, regular physical activity and good sleep hygiene. Managing blood pressure and treating sleep apnoea are also key strategies.