This Canadian review collated data from 97 observational cohort studies looking at all-cause mortality in with adults with a normal BMI – defined as 18.5 to 25 – compared with overweight and obese individuals.
Overweight (BMI between 25 to 30) patients were 6% less likely to die, compared with those that had a normal BMI. Those rated with grade one (BMI of 30 to 35) or two (BMI of 35 or above)obesity were 29% more likely to die from all causes, compared with normal BMI participants. However, there was no significant increase in the risk of death for patients with grade one obesity. This trend continued when the results were limited solely to studies adjusted for age, sex and smoking status.
What does it mean for GPs?
The researchers concluded that these findings were consistent with prior research, showing that overweight patients and those with moderate obesity have no significantly greater risk of death than normal BMI patients. They said the estimates of risks associated with normal weight, overweight and obesity may help to inform clinical decision making.
Dr David Haslam, a GPSI in obesity and cardiometabolic disease in London, said: ‘This study shows comprehensively that we are, as a profession, confused about obesity.
‘There is a definite entity known as the obesity paradox, which suggests that although obesity may be a causative factor in ischaemic heart disease, renal disease and heart failure, once the condition has occurred, a degree of overweight is protective, and that outcomes are improved. Although this piece adds to the confusion, it might ultimately help clarify this paradox.’