Writing in the journal Cell Reports a group of scientists have reported that ‘metabolically healthy’ obese individual display similar genetic profiles to ‘metabolically unhealthy’ individuals in response to insulin suggesting that healthy obesity may be a false assertion.
Prof. Nick Finer, Honorary Professor in the National Centre for Cardiovascular Prevention and Outcome at UCL, and Senior Principal Clinical Scientist with Novo Nordisk, said:
“The concept of maintaining ‘metabolic health’ while being overweight or obese has been extensively explored over recent years, with a number of studies suggesting it is possible to be obese but healthy. However the definitions of obesity (based upon body mass index), metabolic health (based upon the presence or otherwise of insulin resistance, hypertension, abnormal lipids) are all loosely and variably defined. In general the more rigorous the definition of ‘metabolic health’ the more elusive are the individuals who can be identified, finding confirmed by the recent study of Ryden and colleagues.
“Ryden and colleagues tested three groups of individuals – normal weight and healthy, obese (by body mass index) with insulin resistance (who also had a higher blood pressure, fasting glucose, insulin, and triglycerides, and abnormal lipids) and a third group of equally obese individuals but with, on average, more normal insulin, blood pressure and lipid levels. They then exposed the subjects to high levels of insulin and looked at the effect on genes expressed within fat tissue that might mediate adverse health effects. They found little difference in the deleterious response to insulin between the obese groups questioning the validity of calling them ‘metabolically healthy’.
“While these findings do not directly exclude the possibility that there could be a difference in clinical risk or outcomes over time between the groups (this would need a long-term trial looking at hard outcomes such as development of diabetes, or cardiovascular events) it is a further blow to the concept that it is OK to be obese if you don’t show early signs of insulin resistance or diabetes. However imprecise body mass index is, being overweight or obese defined by body mass index is unhealthy and we know that reversing it with weight loss provides metabolic improvement and reduces the risks of diabetes or heart attacks.”
‘The Adipose Transcriptional Response to Insulin Is Determined by Obesity, Not Insulin Sensitivity’ by Ryden et al. published in Cell Reports on Thursday 18th August.
Prof. Nick Finer: Prof Finer is an honorary clinical professor at the National Centre for Cardiovascular Prevention and Outcomes at University College London. He is also an employee of Novo Nordisk, a pharmaceutical company developing and marketing products for the treatment of diabetes and obesity.