How Does Obesity Impact the Heart?

According to Interventional Cardiologist Mun K. Hong, MD, FACC, obesity has multiple harmful effects on the heart, including the heart muscle, the blood vessels, and heart rhythm. Having the extra weight is similar to carrying half of that weight in each hand every second of the day.

For example, if someone is 50 pounds overweight, he/she is carrying 25-pound weight in each hand every second of the day. As you can imagine, this extra weight would cause stress on the heart to result in the heart muscle being thickened, the heart blood vessels developing blockages, and the heart rhythm to be disturbed. In addition, obesity contributes to the development or worsening of high blood pressure, diabetes, and high cholesterol.

On the other hand, weight loss can result in the reversal of these harmful effects. There was a recent study, where obese patients with irregular heart rhythm called atrial fibrillation were divided into two groups, with one group not helped to lose weight and the second group coached and supported to lose weight. The group that lost weight also had resolution of their irregular heart rhythm.    

It is not easy to lose weight, especially if one has been overweight for a long time. However, it is important to change lifestyles, including adding more physical activities, reducing calorie consumption, especially from animal fats, and maintaining a regular sleep pattern. It is thus especially important to help young children and teenagers to adopt a healthy lifestyle to avoid becoming obese.

There is some controversy regarding the use of weight loss prescription medications. It is essential to have close follow-up with physicians. It is not a good idea to use over-the-counter weight loss “medications,” as their safety is not guaranteed.

Q & A with Cardiologist Sung W. Lee, MD

How does being overweight or obese affect your heart?  How does a healthy heart function when compared to the heart of a patient who is overweight?

• Almost all cardiovascular diseases increase in frequency in the setting of obesity, including hypertension, coronary heart disease (CHD), heart failure (HF), and atrial fibrillation (AF).
• Excessive body fat increases blood volume which eventually leads to abnormal enlargement and thickening of the heart.  This can lead to heart failure.
• Overweight patients also tend to develop sleep apnea which causes inadequate breathing and raise blood pressure in the lung. 
• Body fat also increases inflammation and releases hormones that can cause scars in the heart.   

Is there a link between obesity and atrial fibrillation (the most common heart rhythm problem)?

• Around 40 percent of the US population is obese, based on body mass index, and almost 10% are severely obese.  The estimated prevalence in the United States is approximately 5.2 million and is expected to increase to 12.1 million by the year 2030.  The obesity epidemic is partly responsible for a marked increase the prevalence of atrial fibrillation.

How have you seen these problems manifest themselves in your patients?

• Patients with atrial fibrillation most often feel heart beating fast and “flip-flopping."  They feel short of breath and tired.  However, symptoms can be often subtle. 

If you are overweight and begin to diet and exercise, can this help reverse the damage to your heart?

• Lifestyle modifications, including weight loss, have a favorable impact on atrial fibrillation, by lowering the incidence and frequency of atrial fibrillation. 
• Physical activity and cardio-respiratory fitness seem to have a positive impact on atrial fibrillation.