Fat but fit: Obese people can still be ‘metabolically healthy’

A large s ubs e t of pe ople can be obe s e ye t re m ain but m e tabolically he althy and fit, w ith no gre ate r ris k of de ve loping
or dying from he art dis e as e or cance r than norm al w e ight pe ople , according to ne w re s e arch.
The study – published in the European Heart Journal – is the largest ever to have investigated this seeming paradox, say the
researchers, w ho analysed data from over 43,000 US participants. The striking result: being obese does not per se carry such a large
health risk ­ w ith almost half of all obese people classed as ‘metabolically healthy’ and having no greater risk of cardiovascular disease
and cancer than normal w eight people.
Led by Dr Francisco Ortega of the University of Granada, Spain and the Karolinska Institutet, Sw eden, the new study instead reveals
a large subset (46%) of obese people w ho are metabolically healthy – meaning they do they don’t suffer from conditions like insulin
resistance, diabetes and high cholesterol or blood pressure – and w ho have a higher level of fitness than other obese (and even non­
obese) people.
The researchers said that for these people, carrying extra w eight does not seem to have a detrimental effect on health, leading to
w hat is know n as the ‘obesity paradox’.
«It is well known that obesity is linked to a large number of chronic disease such as cardiovascular problems and cancer,» explained
Ortega. «However, there appears to be a sub­set of obese people who seem to be protected from obesity­related metabolic
complications.»
The lead researcher explained that until now it had had not been know n w hether, or how much, people w ho are healthy and fit yet
obese are at risk of obesity related diseases.
«Our study suggests that metabolically healthy but obese people have a better fitness level than the rest of obese individuals,» said
Ortega w ho noted that there are tw o ‘major findings’ to take out of the study:
«Firstly, a better cardio­respiratory fitness level should be considered from now on as a characteristic of this subset of metabolically
healthy obese people. Secondly, once fitness is accounted for, our study shows for the first time that metabolically healthy but obese
individuals have similar prognosis as metabolically healthy normal­weight individuals, and a better prognosis than their obese peers
with an abnormal metabolic profile.»
Study de tails
The project and investigation took place at the University of South Carolina (Columbia, USA) under the direction of Professor Steven
Blair, w ho is responsible for the long­running ‘Aerobics Center Longitudinal Study’ (ACLS) w hich provided the 43,265 participants for
this current analysis.
Participants w ere recruited to the ACLS betw een 1979 and 2003, w ith all completing a detailed questionnaire, including information on
their medical and lifestyle history, in addition to receiving a physical examination that included a treadmill test to assess cardio­
respiratory fitness and measurements of height, w eight, w aist circumference, and their percentage of body fat.
Blood pressure, cholesterol and fasting glucose levels w ere also measured.
Ortega and his colleagues found that 46% of the obese participants w ere metabolically healthy.
After adjusting for several confounding factors, including fitness, the metabolically healthy but obese people had a 38% low er risk of
death from any cause than their metabolically unhealthy obese peers, w hile no significant difference w as seen betw een the
metabolically healthy but obese and the metabolically healthy, normal w eight participants.
The risk of developing or dying from cardiovascular disease or cancer w as reduced by betw een 30­50% for the metabolically healthy
but obese people, and there w ere no significant differences observed betw een them and the metabolically healthy, normal w eight
participants.
Source: European Heart Journal
Published online ahead of print, doi: 10.1093/eurheartj/ehs174
«The intriguing metabolically healthy but obese phenotype: cardiovascular prognosis and role of fitness»
Authors: Francisco B. Ortega, Duck­chul Lee, Peter T. Katzmarzyk, Jonatan R. Ruiz, et al
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