Obesity alone does not increase risk of early death, say scientists who have found that obese patients with no other metabolic risk factors, do not have an increased rate of mortality.
The study could impact how we think about obesity and health, said Jennifer Kuk, an associate professor at York University in Canada.
"This is in contrast with most of the literature and we think this is because most studies have defined metabolic healthy obesity as having up to one metabolic risk factor," said Kuk.
"This is clearly problematic, as hypertension alone increases your mortality risk and past literature would have called these patients with obesity and hypertension, 'healthy'. This is likely why most studies have reported that 'healthy' obesity is still related with higher mortality risk," he added.
Kuk's study showed that unlike dyslipidemia, hypertension or diabetes alone, which are related with a high mortality risk, this is not the case for obesity alone.
The study followed 54,089 men and women from five cohort studies who were categorised as having obesity alone or clustered with a metabolic factor, or elevated glucose, blood pressure or lipids alone or clustered with obesity or another metabolic factor.
Researchers looked at how many people within each group died as compared to those within the normal weight population with no metabolic risk factors.
Current weight management guidelines suggest that anyone with a BMI over 30 should lose weight. This implies that if you have obesity, even without any other risk factors, it makes you unhealthy.
Researchers found that one out of 20 individuals with obesity had no other metabolic abnormalities.
"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," said Kuk.
"This means that hundreds of thousands of people in North America alone with metabolically healthy obesity will be told to lose weight when it's questionable how much benefit they'll actually receive," she said.