Obesity: not automatically a health risk

A new study looked at health risks for people who fit the statistical classification as being obese.

What it found is that if there are no other health concerns evident, the risk of death was not higher for obese people than for lean people.

Lead author Jennifer Kuk (PhD) is an associate professor in the Faculty of Health at York University in Toronto.

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The study was published in the journal “Clinical Obesity” with the title “Individuals with obesity but no other metabolic risk factors are not at significantly elevated all‐cause mortality risk in men and women” (open access here)

Professor Kuk says about a quarter of Canadians fit the definition of obese, while another roughly 25 per cent of the population could be classed as overweight.

The current guidelines suggest that anyone with a body mass index (BMI) of over 30 kg/m2 (classed as obese) even without other health problems or “metabolic risks” are still in theory, unhealthy, and should lose weight.

The study clarifies that previously obese people with only hypertension were classed as “healthy”. Professor Kuk points out that this is not really correct as hypertension alone increases mortality risk.  As such, these individuals should not be classed as metabolically healthy.

Hypertension, dyslipidemia, or diabetes are considered metabolic risks as are a number of other diseases and health factors.

The study looked at over 54,000 men and women in five cohorts; those who are obese but have no other health issues, or obese plus other health concerns, or elevated glucose, blood pressure or lipids alone or clustered with obesity or another metabolic factor.

The study found that obese people with hypertension, diabetes or elevated lipids etc do indeed have higher mortality rates than the average. But, it also found that obese but otherwise healthy people and healthy normal weight people, died at about the same rate.

KuK says, “We’re showing that individuals with metabolically healthy obesity are actually not at an elevated mortality rate. We found that a person of normal weight with no other metabolic risk factors is just as likely to die as the person with obesity and no other risk factors”.

Kuk says what it shows compared to other studies is that obesity on its own does not necessarily indicate a higher mortality rate than for healthy lean individuals.   The differences she says may be due to how metabolically healthy has been defined in the past, and that obese persons with no other health issues are indeed relatively rare about one in 20.