September 26, 2017

Obese people have greater heart health risks—even if they're metabolically healthy, study finds

Daily Briefing

People who are obese are more likely than those who have a normal weight to have a heart attack, stroke, or other types of cardiovascular events—even if they don't have any other risk factors for cardiovascular disease, according to a study published Monday in the Journal of the American College of Cardiology

Learn more about the non-surgical options for treating obesity

Study details

For the study, researchers from the University of Birmingham in England looked at the EHRs of 3.5 million people and categorized them based on their body mass index (BMI), with:

  • 3 percent of participants categorized as underweight, with a BMI of less than 18.5;
  • 38 percent categorized as normal weight, with a BMI of more than 18 but less than 25;
  • 26 percent categorized as overweight, with a BMI of more than 25 but less than 30; and
  • 15 percent categorized as obese, with a BMI of more than 30.  

According to the researchers, all participants were considered metabolically healthy at the start of the study because—aside from some participants' weight—they did not have other risk factors for heart disease, such as diabetes, hypertension, or high cholesterol.

Over a follow-up period of about 5.5 years, the researchers assessed participants' risk for one of four types of cardiovascular disease—coronary heart disease, heart failure, cerebrovascular disease, and peripheral vascular disease—controlling for factors such as tobacco use and contraceptive use. 

Key findings

The researchers found that when compared with metabolically healthy people with a normal BMI, metabolically healthy obese people were 49 percent more likely to develop coronary heart disease and nearly two times as likely to have heart failure. Metabolically healthy obese people were also more likely than their normal-weight peers to have cerebrovascular disease.

On the flipside, the researchers found that people who were underweight and metabolically healthy had a higher rate of vascular disease than those at a normal weight—a finding the researchers said could potentially be linked to smoking, which is associated with a lower BMI and higher risk of vascular problems.

The researchers also found that the likelihood of developing cardiovascular disease rose with the number of metabolic abnormalities an individual had, regardless of their weight. For instance, according to the researchers, about 10 percent of normal-weight people had at least one metabolic abnormality at some point in the study, and they had a higher rate of cardiovascular disease than did normal-weight people who did not have diabetes, hypertension, or high cholesterol. 

However, the researchers cautioned that the study was limited by its reliance on BMI as a measure of obesity. According to the researchers, BMI doesn't distinguish weight from fat versus muscle mass, meaning that people with high levels of muscle mass could be incorrectly categorized as obese based on their overall weight. The researchers also pointed out that the data did not account for diet or exercise.

Discussion

Neil Thomas—a researcher at the University of Birmingham's Institute of Applied Health Research and senior author of the study—said the findings show that while "those 'metabolically healthy' obese people may not have those risk factors we described—diabetes and high blood pressure and blood fats—being obese is already a metabolic abnormality."

He added, "There is no such thing as 'metabolically healthy' and obese."

Citing their other findings on the increased risk for cardiovascular disease based on metabolic abnormalities, regardless of body weight, the researchers added, "Clinicians need to be aware that individuals who would otherwise be considered non-obese, based on a normal BMI, can have metabolic abnormalities, and therefore also be at high risk for cardiovascular disease events."

In an accompanying editorial, Jennifer Bea and Nancy Sweitzer, both from the University of Arizona, echoed those concerns, calling for more screening for cardiovascular disease amongst normal-weight people. "Hypertension and weight screening are routinely performed in adults in the United States, and health providers are urged to treat abnormalities," they said. "The results of this large analysis suggested that screening for abnormalities in lipids and glucose handling should be more systematically monitored as well, regardless of body weight, but particularly in the obese" (Sheridan, STAT News, 9/11; Lou, MedPage Today, 9/11; Rapaport, Reuters, 9/11).

Key insights on medical weight loss programs

 Key insights on medical weight loss programs

As obesity and its related comorbidities remain top concerns nationwide, many hospitals are considering how to enhance their services to this patient group. Understanding that weight loss demands a comprehensive approach to care, many hospitals have launched non-surgical weight loss programs to support those patients who are not candidates for surgery.

This brief profiles three non-surgical weight loss programs at community and teaching hospitals to identify the variety of services available.

Download the Brief

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