British researchers say ‘healthy’ obese people still have a higher risk of cardiovascular disease.

People with metabolically healthy obesity (MHO) are clinically obese in terms of their body mass index (BMI) (more than 30 kg/m2), but do not have metabolic complications that usually come with obesity, such as abnormal blood fats, poor blood sugar control or diabetes, and high blood pressure.

Whether MHO is associated with excess risk of cardiovascular disease (CVD) events is a subject of debate.

Using 20 years’ worth of electronic health records from a giant UK database, researchers at the University of Birmingham assembled a cohort of 3.5 million individuals aged 18 years or older and initially free from CVD.

To determine metabolic health, they divided the population into groups according to BMI and the presence or absence of 3 metabolic abnormalities (diabetes, high blood pressure [hypertension], and abnormal blood fats [hyperlipidemia]) which were added together to create a metabolic abnormalities score (0, 1, 2 and 3). To be classified as MHO, individuals had to have none of these metabolic abnormalities.

The study examined the risk of developing four cardiovascular conditions (coronary heart disease (CHD), cerebrovascular disease (transient ischaemic attack or stroke), heart failure, and peripheral vascular disease (PVD)].

The experts wanted to know if it these were different for normal weight people with no metabolic conditions or people with MHO.

Compared to normal weight individuals with no metabolic abnormalities, individuals with MHO had a 50 per cent increased risk of CHD, a 7 per cent increased risk of cerebrovascular disease and a doubled risk of heart failure.

Intriguingly, MHO individuals had a 9 per cent lower risk of PVD.

Further analyses that excluded cigarette smokers found those individuals with MHO had a significantly (11 per cent) increased risk of developing PVD compared with those with normal weight and zero metabolic abnormalities.

The risk of CVD events in obese individuals appeared to increase with increased number of metabolic abnormalities present.

For example, compared to a normal weight person with zero metabolic abnormalities, an obese person with 3 metabolic abnormalities had a 2.6 times increased risk of CHD; a 58 per cent increased risk cerebrovascular disease including stroke; a 3.8 times increased risk of heart failure, and a 2.2 times increased risk of PVD.

“This is the largest prospective study of the association between metabolically health obesity and cardiovascular disease events,” said researcher Dr Rishi Caleyachetty.

“Metabolically healthy obese individuals are at higher risk of coronary heart disease, cerebrovascular disease and heart failure than normal weight metabolically healthy individuals.

“The priority of health professionals should be to promote and facilitate weight loss among obese persons, regardless of the presence or absence of metabolic abnormalities.”

“At the population-level, so-called metabolically healthy obesity is not a harmless condition and perhaps it is better not to use this term to describe an obese person, regardless of how many metabolic complications they have.”