Unseen fat deposits hidden around the heart may contribute more to the potentially deadly hardening of arteries than visible body fat, according to a study published in the journal Neurology.

Hardening of the arteries, also known as atherosclerosis, occurs when plaque builds up on the walls of the arteries and reduces blood flow. Arterial plaque can be very serious and lead to many different cardiovascular conditions, some of which can be fatal like heart attack and stroke.

In the study, National Institutes of Health researchers asked 183 people with an average age of 61 to undergo a series of magnetic resonance imaging (MRIs) and computed tomography (CT) scans to determine their levels of pericardial fat and arterial plaque buildup. Pericardial fat is found in the area surrounding the heart and just behind the sternum.

Although most participants were slightly overweight, none of them had symptoms of heart disease. However, the scans showed that those who had a significant amount of fat surrounding the heart also had detectable levels of coronary plaque.

The researchers concluded that pericardial fat volume seemed to have a stronger correlation to the accumulation of coronary plaque than either body mass index (BMI) or waist circumference.

Because different people deposit fat in different areas of the body, some pericardial fat is not necessarily cause for alarm. Nonetheless, study authors noted that pericardial fat is often found in people who are overweight or obese, underscoring the importance of leading a healthy lifestyle.

To explore what lifestyle changes you can make to prevent heart diease and improve your cardiovascular health, check out The Components of a Heart Healthy Diet and The Benefits of Exercise for the Elderly.