• Women who are obese face an increased risk of cardiovascular disease, even if they have maintained good metabolic health for decades. (iStockphoto/Getty Images)Source: iStockphoto/Getty Images
A study from Germany has found that your BMI can influence your heart health, even if you’re metabolically healthy - free of diabetes and high cholesterol.
Yasmin Noone

31 May 2018 - 9:03 AM  UPDATED 31 May 2018 - 9:10 AM

Obese women who consider themselves healthy – showing no signs of diabetes, high blood pressure or high cholesterol – may still face a high risk of developing cardiovascular disease (CVD) in the future, according to a new German study.

The research, published today in The Lancet Diabetes & Endocrinology journal, observed over 90,000 American female nurses for around 30 years to determine whether metabolic healthy, obese women were at a greater risk of CVD than metabolically healthy women of normal weight.

The results showed that obesity is a risk factor for CVD cardiovascular disease.

Researchers from German Institute of Human Nutrition Potsdam-Rehbruecke found that it didn’t matter if the women with obesity were in good metabolic health and maintained a satisfactory level of blood pressure and didn’t have type 2 diabetes over decades.

“Even if women with obesity maintained metabolic health over 10 or 20 years, they were at an increased risk compared with women with normal weight,” the study reads.

“These findings suggest that individuals who are metabolically healthy might benefit from early behavioural and medical management focusing on preventing progression to being metabolically unhealthy (for example, by improving overall diet and increasing physical activity).”

“Even if women with obesity maintained metabolic health over 10 or 20 years, they were at an increased risk compared with women with normal weight,” the study reads.

Metabolically unhealthy normal weight women were around 2.5 times more likely to develop CVD compared to normal weight women with no metabolic abnormalities. Women who lived with ‘metabolically healthy obesity’ faced a 39 per cent higher risk of CVD.

The study also found that the majority of metabolically healthy women are likely to become metabolically unhealthy over time, regardless of their BMI status.

The study also found that women who maintained metabolically healthy obesity over 20 years had a 57 per cent higher risk of developing CVD compared with normal weight metabolically healthy women.

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“Our data suggest that a longer exposure to the metabolically unhealthy status is associated with a greater cardiovascular disease risk,” the study reads.

The results also highlight that diabetes and hypertension had the largest effect on cardiovascular disease risk in women who were metabolically healthy at the start of the study.

“This is not surprising considering that both diabetes and hypertension are strong risk factors for cardiovascular disease.”

Metabolically healthy and obese: What does it mean?

Obesity is determined when a person has a Body Mass Index (BMI) of more than 30kg/m².

It affects almost all of the cardiovascular disease risk factors, particularly those related to metabolic syndrome including high blood pressure, poor blood sugar control or diabetes, and abnormal blood fats, which double the risk of cardiovascular disease such as heart attacks and stroke.

According to a study published in 2017, obesity is linked to a reduced life expectancy, because obese individuals are at an increased risk of type 2 diabetes, cardiovascular disease, and some cancers.

“However, not all obese subjects are at a higher risk of mortality, which suggests that there is a subset of healthy obese individuals, i.e., those exhibiting so-called “metabolically healthy obesity”,” the study led by Chang Hee Jung reads.

The term ‘metabolically healthy obesity’ describes people who are obese but seem to be free of illness and related diseases.

“This is not surprising considering that both diabetes and hypertension are strong risk factors for cardiovascular disease.”

The new German study published in The Lancet investigated the concept of metabolic health and obesity by looking at the incidence of CVD for women aged 30-55 years occurring between 1980 and 2010, using data from the Nurses’ Health Study. At the start of the research period, all the women were free from CVD.

Participants were divided into groups by BMI category, metabolic health, and change in metabolic health status. They were sent questionnaires every two years to update their BMI and metabolic health status, and to assess their lifestyle, health behaviour, and medical history.

During an average follow-up of 24 years, over 6,300 new cases of cardiovascular disease, including 3304 heart attacks and 3080 strokes were recorded. Cardiovascular disease risk was especially high in all metabolically unhealthy women, regardless of their BMI.

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What about fitness?

Lead author of a comment linked to the study, Professor Carl Lavie from the University of Queensland School of Medicine, New Orleans (USA) says although the study provides an important insight into CVD, metabolism and weight, it does not take fitness into account.

Prof Lavie and colleagues suggest that cardiorespiratory fitness, may be one of the strongest predictors of CVD and death from CVD.

They believe that when studies are adjusted to factor in exercise or cardiorespiratory fitness, metabolically healthy obesity might not be associated with increased risk of cardiovascular disease mortality.

“Although all of the studies raised the idea that obesity can never be healthy, we have argued that fitness is more important than fatness, and those with metabolically healthy obesity and decent levels of cardiorespiratory fitness have a quite good overall prognosis from cardiovascular disease and overall survival," says Prof Lavie and colleagues. 

Prof Lavie and colleagues call for "drastic efforts" to be made to prevent obesity in the first place and, especially, to prevent people who are already obese, gaining more weight and becoming metabolically unhealthy. 

“Public health policies aiming to increase cardiorespiratory fitness through physical activity and exercise will further contribute to improve people’s health. It is prudent to remind ourselves that an ounce of prevention is better than a pound of cure.”

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