Study shows so-called 'healthy obesity' is harmful to cardiovascular health

September 11, 2017
Credit: University of Birmingham

Clinicians are being warned not to ignore the increased cardiovascular health risks of those who are classed as either 'healthy obese' or deemed to be 'normal weight' but have metabolic abnormalities such as diabetes.

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, published today (September 11th) 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 - 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 5 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:

1. Underweight (BMI less than 18.5)

2. Normal weight (more than 18 but less than 25)

3. Overweight (more than 25 but less than 30)

4. Obese (more than 30).

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

The results showed that those who were MHO had a 49 per cent higher risk of coronary heart disease, seven per cent higher risk of cerebrovascular disease and a 96 per cent 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.

The research results raise 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.

Lead author and epidemiologist Dr Rishi Caleyachetty, of the Institute of Applied Health Research University of Birmingham, said: "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.

"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."

Senior author Professor Neil Thomas, also of the University of Birmingham, said it was important that clinicians took on board the research findings.

"The finding that normal weight individuals with metabolic abnormalities also had similar risk of cardiovascular disease events than normal weight metabolically healthy individuals has important implications." he added.

"In many countries it is currently recommended that clinicians in primary care settings use overweight and obesity as the main criteria to screen adults for cardiovascular risk factors as part of cardiovascular risk assessment. Our research suggests that this could result in the failure to identify metabolic abnormalities, such as diabetes, high blood pressure and high cholesterol, in many normal weight patients."

Senior author and Public Health physician Dr Krish Nirantharakumar, also of the University of Birmingham, said: "We conclude that obese patients, irrespective of their metabolic status, should be encouraged to lose weight and that early detection and management of normal weight individuals with metabolic abnormalities will be beneficial in the prevention of CVD events."

Explore further: Study of 3.5 million people shows 'healthy' obese people are still at higher risk of cardiovascular disease events

More information: Metabolically healthy obese and incident cardiovascular disease events among 3.5 million men and women, Journal of the American College of Cardiology (2017). DOI: 10.1016/j.jacc.2017.07.763

Related Stories

Study of 3.5 million people shows 'healthy' obese people are still at higher risk of cardiovascular disease events

May 17, 2017
New research presented at this year's European Congress on Obesity (ECO) in Porto, Portugal (17-20) May shows that so called 'metabolically healthy' obese people are still at higher risk of cardiovascular disease events such ...

Characteristics of metabolically unhealthy lean people

August 1, 2017
Compared to people who are of normal weight and metabolically healthy, subjects who are of normal weight but metabolically unhealthy (~20 percent of normal weight adults) have a more than three-fold higher risk of mortality ...

'Fat but fit' are at increased risk of heart disease

August 14, 2017
Carrying extra weight could raise your risk of heart attack by more than a quarter, even if you are otherwise healthy.

Over 50 percent of obese Spanish workers are metabolically healthy

March 31, 2016
About half of obese individuals in a working population in Spain are metabolically healthy - they are obese but do not present metabolic abnormalities like disturbed insulin signaling or inflammation, according to a study ...

Metabolically healthy obesity does not guarantee clean bill of health

November 20, 2013
Obese people who are currently metabolically healthy face a higher risk of developing diabetes and cardiovascular disease, according to new research accepted for publication in The Endocrine Society's Journal of Clinical ...

Higher risk of chronic kidney disease in 'healthy' obese

February 10, 2016
(HealthDay)—Overweight and obesity are associated with increased risk of development of chronic kidney disease (CKD), even in patients who are metabolically healthy, according to research published online Feb. 9 in the ...

Recommended for you

Could this protein protect people against coronary artery disease?

November 17, 2017
The buildup of plaque in the heart's arteries is an unfortunate part of aging. But by studying the genetic makeup of people who maintain clear arteries into old age, researchers led by UNC's Jonathan Schisler, PhD, have identified ...

New model estimates odds of events that trigger sudden cardiac death

November 16, 2017
A new computational model of heart tissue allows researchers to estimate the probability of rare heartbeat irregularities that can cause sudden cardiac death. The model, developed by Mark Walker and colleagues from Johns ...

Raising 'good' cholesterol fails to protect against heart disease

November 16, 2017
Raising so-called 'good' cholesterol by blocking a key protein involved in its metabolism does not protect against heart disease or stroke, according to a large genetic study of 150,000 Chinese adults published in the journal ...

Popular e-cigarette liquid flavorings may change, damage heart muscle cells

November 16, 2017
Chemicals used to make some popular e-cigarette liquid flavorings—including cinnamon, clove, citrus and floral—may cause changes or damage to heart muscle cells, new research indicates.

Possible use for botulinum toxin to treat atrial fibrillation

November 16, 2017
From temporarily softening wrinkles to easing migraines, botulinum toxin has become a versatile medical remedy because of its ability to block nerve signals that can become bothersome or risky.

Proteome of the human heart mapped for the first time

November 15, 2017
A healthy heart beats about two billion times during a lifetime, thanks to the interplay of more than 10,000 proteins. Researchers from the Max Planck Institute of Biochemistry (MPIB) and the German Heart Centre at the Technical ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.