Overweight people who otherwise seem healthy are still exposed to a high risk of coronary heart disease, a new study shows.
The National Institute of Diabetes and Digestive and Kidney Diseases show that more than two in three adults, as well as around one third of all children and teenagers, are overweight or obese in the United States.
Adult obesity is also linked with many negative health effects, including a higher risk of mortality, hypertension, type 2 diabetes, and coronary heart disease, according to the Centers for Disease Control and Prevention (CDC).
However, there is also a type of obesity known as "metabolically healthy obesity," which is usually taken to refer to people with a higher-than-normal body mass index (BMI) but no identifiable health issues.
Drs. Camille Lassale and Ioanna Tzoulaki, from Imperial College London in the United Kingdom, alongside colleagues from the University of Cambridge, also in the U.K., have conducted a study that compares the data of both "healthy" and "unhealthy" obese individuals.
They have found that, despite previous expectations, people deemed to be "healthy obese" were still very likely to develop coronary heart disease at some point in their lifetime. The study's findings are published in the current issue of the European Heart Journal.
'Healthy overweight' still at risk
This study worked with data collected from 519,978 people (366,521 women and 153,457 men), all of whom were aged 35 to 70 years old, using the European Prospective Investigation Into Cancer and Nutrition of the World Health Organisation (WHO). The participants came from 10 different countries, which were Denmark, France, Germany, Greece, Italy, the Netherlands, Norway, Spain, Sweden, and the U.K.
All the participants were followed-up for a median period of 12.2 years, during which 7,637 cases of coronary heart disease were recorded.
The researchers categorized the participants according to their BMI, as calculated using WHO guidelines. A BMI of 18.5 to 24.9 indicated normal body weight, a BMI of 25 to 29.9 fell into the overweight category, and a BMI of 30 or over indicated obesity.
Of the study participants, 63 percent were female, they had an average age of 53.6, and they exhibited average BMIs of 26.1.
Individuals were also deemed "metabolically unhealthy" if they exhibited three or more metabolic factors, such as high blood pressure, high blood sugar, abnormal triglyceride levels, low levels of "good" cholesterol, or a larger-than-normal waist size (defined as larger than 94 centimeters for men, and larger than 80 centimeters for women).
The participants' health status was compared against that of a control group of more than 10,000 metabolically healthy individuals.
It was found that participants who fell into the metabolically unhealthy category - regardless of whether they had a normal weight, were overweight, or were obese - had more than twice the risk of developing coronary heart disease than their metabolically healthy counterparts.
These results held strong even after controlling for relevant factors that might have impacted the outcomes, such as the participants' smoking and dietary habits, physical exercise patterns, and socioeconomic status.
What was more surprising, however, was that overweight and obese people apparently falling into the metabolically healthy category also presented a high risk of developing coronary heart disease when compared with their peers of a normal weight.
Participants classed as overweight but metabolically healthy had a 26 percent higher risk of coronary heart disease than their normal weight counterparts, and metabolically healthy obese participants had a 28 percent higher risk of coronary heart disease.
Excess weight and coronary heart disease
According to the researchers, these findings demolish the myth of the healthy overweight or obese person. "I think there is no longer this concept of healthy obese. If anything, our study shows that people with excess weight who might be classed as 'healthy' haven't yet developed an unhealthy metabolic profile. That comes later in the timeline, then they have an event, such as a heart attack," says Dr. Tzoulaki.
Nonetheless, the researchers note that it is not the excess weight that causes people to be at a high risk of coronary heart disease. Instead they suggest that this is probably caused by other factors associated with obesity, such as high blood pressure and hyperglycemia, or high blood sugar.
Although no follow-up measurements were taken to see how the participants' health status may have changed over time, specialists involved in the study are convinced that taking steps to counteract excess weight and obesity, regardless of how healthy a person may appear to be, is crucial to preventing heart disease.
"Our findings suggest that if a patient is overweight or obese, all efforts should be made to help them get back to a healthy weight, regardless of other factors. Even if their blood pressure, blood sugar, and cholesterol appear within the normal range, excess weight is still a risk factor."
Dr. Camille Lassale