Too much belly fat, even for people with a healthy BMI, raises heart risks

People with too much fat around their midsections and vital organs are at increased risk for heart disease, even if their body mass index falls within what is considered a healthy range, according to a new scientific report.

The statement from the American Heart Association, published Thursday in its journal Circulation, summarizes research on the ways in which belly fat and other measures of obesity affect heart health. Belly fat also is referred to as abdominal fat and visceral adipose tissue, or VAT.

“Studies that have examined the relationship between abdominal fat and cardiovascular outcomes confirm that visceral fat is a clear health hazard,” writing committee chair Dr. Tiffany Powell-Wiley said in a news release. Powell-Wiley is chief of the Social Determinants of Obesity and Cardiovascular Risk Laboratory at the National Heart, Lung, and Blood Institute in Bethesda, Maryland.

Whether a person has too much belly fat is typically determined using the ratio of waist circumference to height (taking body size into account) or waist-to-hip ratio. This measurement has been shown to predict cardiovascular death independent of BMI, a measure of obesity that is based on height and weight.

Experts recommend both abdominal measurement and BMI be considered during regular health care visits because even in healthy weight individuals, it could mean an increased heart disease risk. Abdominal obesity is also linked to fat accumulation around the liver. That often leads to non-alcoholic fatty liver disease, which adds to cardiovascular disease risk.

Worldwide, around 3 billion people are overweight or have obesity. The “obesity epidemic contributes significantly” to many chronic health conditions and cardiovascular disease cases around the world, Powell-Wiley said. Specifically, obesity is associated with a higher risk of coronary artery disease and death from cardiovascular disease. It contributes to high cholesterol, Type 2 diabetes, high blood pressure and sleep disorders.

Yet some people whose BMI classifies them as obese, but who have low levels of abdominal fat, are at lower risk for heart problems, the analysis showed.

Meeting federal guidelines for 150 minutes of physical activity per week may be sufficient to reduce abdominal fat, the analysis found, with no additional loss from longer activity times. Exercise alone or in combination with diet changes have been shown in some instances to reduce abdominal obesity even without weight loss.

Also, weight loss from lifestyle changes improves blood sugar, blood pressure, and triglyceride and cholesterol levels – a cluster of factors referred to as metabolic syndrome, according to the new statement. It also reduces inflammation, improves blood vessel function and helps non-alcoholic fatty liver disease.

In addition, intense weight loss may help curb atrial fibrillation, a quivering or irregular heartbeat, according to the report. Estimates suggest obesity may account for one-fifth of all cases.

The new scientific statement evaluated research on managing and treating obesity, particularly abdominal obesity. Experts concluded that reducing calories and aerobic exercise were the most beneficial.

Bariatric weight loss surgery has been shown to reduce the risk for coronary artery disease better than weight loss achieved without surgery. This may be due to the larger amount of weight loss achieved with surgery and the resultant changes in metabolism that are typical after bariatric surgery.

The statement also addresses what’s known as the “obesity paradox.” That is, even though overweight and obesity are strong risk factors for cardiovascular disease, in the short-term, they don’t always mean patients have worse survival outcomes. The analysis concludes this may be because people classified as overweight or obese are often screened earlier for cardiovascular disease than people with healthy weight, so they are diagnosed and treated earlier.

“The underlying mechanisms for the obesity paradox remain unclear,” Powell-Wiley said. “Despite the existence of the paradox for short-term cardiovascular disease outcomes, the data show that patients with overweight or obesity suffer from cardiovascular disease events at an earlier age, live with cardiovascular disease for more of their lives and have a shorter average lifespan than patients with normal weight.”

Article published courtesy of American Heart Association News

African Americans who smoke seem at higher risk of coronary heart disease

African Americans who smoke appear to have more than twice this risk of  developing coronary heart disease compared to those who do not smoke, a new study has found. The findings — the first up-close look at the relationship between smoking and coronary heart disease in this population—also examined the risk for plaque buildup in the arteries of African Americans who smoke. Excessive plaque in the arteries is a known predictor of heart attacks and heart failure.    

 The study, published today in the Journalof the American Heart Association, draws on data from nearly 4,500 participants in the Jackson Heart Study, the largest cohort study investigating cardiovascular disease exclusively in African Americans. That study, as well as the new research, is supported by the National Heart, Lung, and Blood Institute (NHLBI), and the National Institute of Minority Health and Health Disparities (NIMHD), both part of the National Institutes of Health.    

Coronary heart disease, the leading cause of death in the world, is the most common type of heart disease. In the United States, it affects more than 20 million adults(link is external) and causes one in seven deaths, according to the Centers for Disease Control and Prevention. It can develop when plaques build up in the blood vessels that supply the heart. These clogged, or calcified, arteries can limit or block blood flow and increase the risk for heart attack.    

Compared to whites, African Americans are more likely to die from coronary heart disease. Cigarette smoking causes inflammation and atherosclerosis, and coronary heart disease. Despite a marked decline in smoking among African American adults in recent years, almost 15% reported current cigarette smoking in 2019. Yet the link between cigarette smoking and coronary heart disease has been understudied in this population.    

African Americans have disproportionally higher rates of hypertension, diabetes, and obesity—known risk factors that partly explain the greater death toll from coronary heart disease in this community, according to the researchers.    

“But smoking is also a well-documented risk factor, which, combined with the others, suggest that African Americans smokers represent a particularly vulnerable population for this disease,” said lead study author Adebamike Oshunbade, M.D., M.P.H., a postdoctoral research fellow at the University of Mississippi Medical Center in Jackson. “However, our study is the first to focus on the relationship between cigarette smoking and coronary heart disease exclusively among a large cohort of African Americans.”      

Given the scant inclusion of African Americans in prior studies, researchers had limited ability to single out the specific effects of smoking, distinct from other risk factors, in this population. But with the Jackson Heart Study cohort of 5,306 participants, Oshunbade and colleagues were able to assess the relationship between smoking, coronary heart disease, and coronary artery calcification in African American adults.   

The investigators used coronary artery calcification (CAC) score measurements to assess the degree of calcified plaque buildup in participants’ coronary arteries. CAC score, which is measured by a CT scan, is a key predictor of an individual’s risk for cardiac events like heart attacks.      

For the study, 4,432 participants without a history of coronary heart disease at the time (2000-2004), were classified as current smokers, former smokers, or never smokers. After taking into account other risk factors — including smoking intensity, or the number of cigarettes each consumed daily — researchers followed the participants through 2016, tracking the development of coronary heart disease.     

The researchers found that, compared to those who never smoked, those who currently smoked had a more than two-fold higher risk of coronary heart disease. Similarly, those who smoke had an increased likelihood of having a higher CAC score.   

   “Smoking is a modifiable risk factor for cardiovascular disease and 73% of African American adults who smoke want to quit,” said David Goff, M.D., Ph.D., director of the NHLBI’s Division of Cardiovascular Sciences. “However, compared to whites, African American patients are less likely to receive information about smoking cessation treatments that we know can make a difference. Fully addressing tobacco-related disparities requires addressing conditions where people live, work, and play.” 

As the authors noted, the study was observational, and the findings do not establish casual links. Additionally, they should not be generalized to people of other races or regions.