Further cardiovascular evidence suggests there is no such thing as “healthy obesity”

11 Sep 2017 --- Clinicians have been warned by the results of a University of Birmingham study not to ignore the increased cardiovascular health risks of those who are either classed as “healthy obese” or deemed to be “normal weight” while having metabolic abnormalities such as diabetes.

The study follows similar findings by a group of researchers at Imperial College London and the University of Cambridge last month, which suggest that being overweight or obese increases a person’s risk of coronary heart disease (CHD) by up to 28 percent compared to those with a healthy body weight, even if they have healthy blood pressure, blood sugar and cholesterol levels.

“These data confirm the importance our lifestyle plays in our health and the need for appropriate nutritional advice to help, ideally, prevent the development of overweight and obesity, but also as part of an approach to treating the problem,” senior author Professor Neil Thomas tells NutritionInsight. “The earlier it is addressed, the more likely it is to be successful.”

“Those who are successful in losing and, most importantly, maintaining the weight loss do so by a complete long-term change in their approach to life,” Thomas adds. “Simply ‘crash’ dieting is not the answer.”

Millions of records investigated
Academics at the University of Birmingham’s Institute of Applied Health Research carried out the largest study of its kind to date comparing weight and metabolic status to cardiovascular disease risks, and it was published on 11 September in the Journal of the American College of Cardiology.

The study showed that individuals who are “metabolically healthy obese” (MHO) – those who are obese but do not suffer metabolic abnormalities such as diabetes, high blood pressure and high cholesterol – still have an increased risk of cardiovascular disease events compared to those who are normal weight without metabolic abnormalities.

The academics used electronic health records of 3.5 million British adults who were all initially free of cardiovascular disease (CVD). They then revisited each patient’s record, at an average of five years and four months later, in order to assess whether they had gone on to develop each of four kinds of CVD events – coronary heart disease (CHD), cerebrovascular disease (in particular strokes), heart failure or peripheral vascular disease (PVD).

Patients were divided into four “body size phenotypes” using Body Mass Index (BMI), which is calculated by dividing body weight (kg) by height (m) squared: underweight (BMI less than 18.5), normal weight (more than 18 but less than 25), overweight (more than 25 but less than 30) and obese (more than 30).

Three metabolic abnormalities were taken into consideration during the study: diabetes, hypertension and hyperlipidemia. A metabolically healthy person was classified as having no metabolic abnormalities.

The results showed that those who were MHO had a 49 percent higher risk of coronary heart disease, 7 percent higher risk of cerebrovascular disease and a 96 percent increased risk of heart failure than normal weight metabolically healthy individuals.

Importantly, it also showed that “normal weight” individuals with one or more metabolic abnormalities had an increased risk of CHD, cerebrovascular disease, heart failure and PVD compared to normal weight individuals without metabolic abnormalities.

Questions to be asked
The research results raise further questions around the concept of “healthy obesity.” Whether metabolically healthy obesity is associated with excess risk of cardiovascular disease has remained a subject of debate for many years due to limitations in previous studies. Academics at the University of Birmingham sought to address these limitations in the largest prospective study of its kind.

“In our study, we had unprecedented statistical power to examine body size phenotypes by the number of metabolic abnormalities, potentially reflecting several definitions of the ‘metabolically healthy’ phenotype in relation to a range of CVD events,” says lead author and epidemiologist Dr. Rishi Caleyachetty of the Institute of Applied Health Research University of Birmingham. “Obese individuals with no metabolic risk factors are still at a higher risk of coronary heart disease, cerebrovascular disease and heart failure than normal weight metabolically healthy individuals.”

“So-called ‘metabolically healthy’ obesity is clearly not a harmless condition, and the term should no longer be used in order to prevent misleading individuals that obesity can be healthy,” Caleyachetty continues.

“Metabolically healthy obese and incident cardiovascular disease events among 3.5 million men and women” by Caleyachetty et al. is published in the Journal of The American College of Cardiology.