Carrying
extra weight could raise your risk of heart attack by more than a quarter, even
if you are otherwise healthy.
Researchers
have found that being overweight or obese increases a person's risk of coronary
heart disease (CHD) by up to 28 per cent compared to those with a healthy
bodyweight, even if they have healthy blood pressure, blood sugar and
cholesterol levels.
The
findings add to a growing body of evidence that suggests being 'fat but fit' is
a myth, and that people should aim to maintain a body weight within a healthy
range.
Storing
too much fat in the body is associated with a number of metabolic changes,
including increased blood pressure, high blood sugar and altered cholesterol
levels, which can lead to disease and poor health. However, previous studies
have revealed a subset of overweight people who appear to lack the adverse
health effects of excess weight, leading to them being classified as
'metabolically healthy obese' in the medical literature, and 'fat but fit' in
the media.
Now,
a group led by researchers at Imperial College London and the University of
Cambridge has shown that despite an apparent clean bill of health, this
overweight group is still at increased risk compared to those with a healthy
weight. In the largest study of its kind to date, scientists used data from
more than half a million people in 10 European countries -- taken from the
European Prospective Investigation into Cancer and Nutrition (EPIC) -- to show
that excess weight is linked with an increased risk of heart disease, even when
people have a healthy metabolic profile.
"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" said lead author Dr
Camille Lassale, from Imperial's School of Public Health and now based at
University College London.
In
the study, published in the European Heart Journal, researchers looked
at the link between excess weight and risk of CHD, a condition where not enough
blood gets through to the heart due to clogged arteries, leading to heart
attacks.
After
a follow-up period of more than 12 years, a total of 7,637 people in the EPIC
cohort experienced CHD events, such as death from heart attack. Researchers
then selected a representative group of more than 10,000 individuals as
controls, for analysis.
Body
weight was classified according to definitions from the World Health
Organization. Those with a body mass index (BMI) over 30 were classed as obese,
while those with a BMI of 25-30 were classed as overweight, and 18.5-25 as
normal weight. More than half of the control group (63 per cent) were female,
with an average age of 53.6 and an average BMI of 26.1.
Participants
were categorised as 'unhealthy' if they had three or more of a number of
metabolic markers, including high blood pressure, blood glucose, or
triglyceride levels, low levels of HDL cholesterol, or a waist size of more
than 37" (94 cm) for men and 31" (80 cm) for women.
After
adjusting for lifestyle factors such as smoking, diet, exercise and
socioeconomic status, the researchers found that compared to the healthy normal
weight group, those classed as unhealthy had more than double the risk of CHD,
whether they were normal weight, overweight or obese.
However,
analysis also revealed that within the apparently healthy group there was a
significant difference in outcomes for people depending on their weight. The
research found that compared to those at normal weight, people who were classified
as healthy but were overweight had an increased CHD risk of 1.26 (26 per cent),
while those who were healthy but obese had an increased risk of 1.28 (28 per
cent).
Dr
Ioanna Tzoulaki, from Imperial's School of Public Health, said: "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."
According
to the researchers, the excess weight itself may not be increasing the risk of
heart disease directly, but rather indirectly through mechanisms such as
increased blood pressure and high glucose. They add that as no follow up measurements
were taken, they cannot show how the group's health status changed over time.
However, they add that what is clear from the study is that population-wide
prevention and treatment of obesity is needed in order to ensure public health.
Dr
Lassale added: "Overall, our findings challenge the concept of the
'healthy obese'. The research shows that those overweight individuals who
appear to be otherwise healthy are still at increased risk of heart
disease."
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