The prevalence of metabolic health in American adults is 'alarmingly low,' even among people who are normal weight, according to a new study from the University of North Carolina at Chapel Hill's Gillings School of Global Public Health. Only one in eight Americans is achieving optimal metabolic health. This carries serious implications for public health since poor metabolic health leaves people more vulnerable to developing Type 2 diabetes, cardiovascular disease and other serious health issues.

This study, published Nov. 28 in the journal Metabolic Syndrome and Related Disorders, presents the most updated U.S. data on metabolic health, which is defined as having optimal levels of five factors: blood glucose, triglycerides, high-density lipoprotein cholesterol, blood pressure, and waist circumference, without the need for medications.

For the study, researchers examined National Health and Nutrition Examination Survey data from 8,721 people in the United States between 2009 and 2016 to determine how many adults are at low versus high risk for chronic disease. Data revealed that only 12.2 percent of American adults are metabolically healthy, which means that only 27.3 million adults are meeting recommended targets for cardiovascular risk factors management.

In the last decade the thresholds for common health measures, for example those that are used to determine if someone has high blood pressure or blood sugar levels, have been lowered by respected professional medical societies. These more restrictive guidelines may mean that a smaller proportion of people are meeting the optimal levels for the cardiovascular risk factors.

"The study fills a gap. We wanted to know how many American adults really meet the guidelines for all of these risk factors and are within optimal levels for disease prevention and health," said Joana Araujo, postdoctoral research associate in nutrition and the study's first author. "Based on the data, few Americans are achieving metabolic health, but the most disturbing finding was the complete absence of optimal metabolic health in adults who had obesity, less than a high school education, were not physically active and were current smokers. Our findings should spur renewed attention to population-based interventions and widely accessible strategies to promote healthier lifestyles."

The data showed that being more physically active, female, younger, more educated and a nonsmoker were factors associated with being more metabolically healthy. Whereas, being non-Hispanic black or having a higher body mass index meant people were less likely to be metabolically healthy.

The research team looked at how health-related behaviors might play into metabolic health and how the proportion of people who are metabolically healthy changes when BMI, physical activity or smoking rates are higher or lower. They found that less than 1 percent of obese adults are metabolically healthy. On the other hand, people who exercise more appear to have higher levels of metabolic health.

The authors call for further study to understand the mechanisms of risk factor development, with a focus on people of normal weight as well as heavier adults.

Araujo's co-authors are Jianwen Cai, and June Stevens, both of the UNC Gillings School.