What effect does weight have on the cardiovascular system?

Obesity is associated with an increased risk of developing numerous cardiovascular diseases including:

• hypertension
• coronary heart disease
• heart failure
• stroke

Obesity also increases the risk of premature death from cardiovascular disease – this association is particularly strong for those with abdominal obesity. Almost 70% of deaths related to overweight and obesity are due to cardiovascular disease, and 60% of those deaths occur in people who have a body mass index (BMI) greater than 30 kg/m2¹¹.

Mechanism by which obesity influences the disease state

Obesity increases risk factors of cardiovascular disease, such as elevated blood pressure, plasma lipids, glucose/insulin resistance and inflammation. Several mechanisms are involved. One mechanism is that excess adipose tissue elevates the circulating blood volume which increases left ventricular stroke volume and leads to higher cardiac output. These changes place enormous burden on the heart (hypertension) by causing ventricular alterations, ultimately leading to ventricular hypertrophy and enlargement, increasing the risk of developing heart failure¹².

There are also systemic mechanisms at play. Adipose tissue secretes a range of bioactive mediators including leptin, adiponectin, interleukin-6 and tumour necrosis factor-α and cause disruptions to body weight homeostasis as well as insulin resistance, inflammation, dysregulation of lipid levels, coagulation and fibrinolysis and contributes to atherosclerotic build up¹³. This can lead to poor blood flow, and potential blockages, both important risk factors for ischemic stroke and coronary heart disease.

Benefits of weight management and lifestyle interventions

• Obesity is considered a ‘major modifiable risk factor’ for coronary heart disease. An increase of each unit of BMI above a healthy weight increases the risk of coronary heart disease by 8%¹⁴. Therefore, lifestyle interventions to reduce body weight, including caloric restriction and physical activity, can reduce risk of cardiovascular disease.
• Physical activity attenuates, the adverse effects of obesity on cardiovascular health ¹³. An increase of 1 MET (metabolic equivalent (1 kcal/kg of body weight/hour)) in physical activity is associated with an 8% decrease in risk of coronary heart disease¹³. It is therefore highly beneficial for a patient with overweight or obesity to increase their physical activity, even if they do not see the results translating to weight loss straight away.