In clinical practice, it is not uncommon to meet individuals who, despite meeting the BMI criteria for obesity, appear metabolically healthy: their glucose, lipid and blood pressure levels are well within the normal range. According to the Edmonton Obesity Staging System (EOSS), we would refer to these individuals as having “Stage O” obesity.
But are these apparently metabolically healthy obese individuals really healthy in that they have a lower mortality risk than obese individuals with metabolic abnormalities?
This question was addressed by Jennifer Kuk and colleagues from York University, Toronto, Canada, in a paper just published in Diabetes Care.
Kuk and colleagues examined data from 6,011 men and women from the Third National Health and Nutrition Examination Survey (NHANES III) where metabolically abnormal was defined as having insulin resistance (IR) or two or more metabolic syndrome (MetS) criteria.
A total of 30% of obese subjects had IR, and 38.4% had two or more MetS factors, whereas only 6.0% (or 1.6% of the whole population) were free from both IR and all MetSyn factors.
Based on the mortality data over 8 years, both the metabolically healthy and metabolically abnormal obese individuals had around the same roughly 2.5 to 3-fold elevation in mortality risk compared to the metabolically normal normal-weight individuals.
The authors conclude that even in the absence of overt metabolic aberrations, excess weight is associated with increased all-cause mortality risk.
Thus, as I’ve said before, it appears that there is no such thing as “benign” obesity. Eventually excess weight will increase the risk for a wide range of health problems including cancers, osteoarthritis and obstructive sleep apnea. This is why it is critical to include the assessment of all four Ms in patients presenting with excess weight.
So how do these findings impact on weight loss recommendations in obese individuals who appear metabolically normal (EOSS 0)?
As blogged before, the first step in weight management is prevention of weight gain. As a rule, this will require substantial changes in diet and activity levels as well as mitigation of any underlying root causes of positive energy balance – this alone can be difficult enough to achieve.
With current conservative obesity treatments only a small minority of patients will achieve and maintain clinically relevant weight loss – the vast majority of weight-losers will simply yo-yo back to their excess weight. I therefore maintain that for most obese individuals weight stabilization may be a far more realistic and sustainable goal than losing weight and keeping it off.
It is also important to remember that associations (as in this paper) do not imply causality and that these new findings therefore cannot be seen as certain proof that weight loss will decrease risk or increase longevity. This question can only be resolved with appropriately designed and conducted intervention trials.
Nevertheless the data should give caution to the notion that excess weight in metabolically healthy adults is harmless.
Prevention of weight gain is likely beneficial irrespective of obesity stage and should be the primary goal of all weight management interventions.