The media are constantly harping on about the obesity epidemic – “two in three of us are fat – this is going to lead to an explosion of obesity related morbidity – heart disease, cancer, cerebrovascular disease, crumbling joints etc.” It never seems to occur to the same talking heads on television and in print media that life expectancy continues to improve worldwide, without any great new medical advances over the past 2 decades (during which the obesity epidemic emerged). In perioperative medicine and critical care we have data that an “obesity paradox” exists – that individuals with a BMI between 25 and 35 (overweight and grade 1 obesity) have lower mortality rates in perioperative medicine (references 1. Here, 2. Here) and critical illness (references 1. Here; 2 Here; 3 Here; 4. Here). The reasoning why overweight and mild obesity (being chubby) may confer benefit is an increase in physiology reserve, delivered in part by an increase in lean body mass. As patients become heavier (body mass index; BMI>35, grade 2 and 3 obesity), they start manifesting mass related injury and metabolic disease. Metabolic syndrome unquestionably increases long term risk (here).
But what of the general population? Life insurance companies continue to penalize chubby folks based on actuarial figures from the 1960s – it that fair? It turns out that it is not. Hold your breath – a 2.88 million patient meta analysis performed by a group of US researchers and published in last week’s JAMA (here), has completely moved the goalposts for desirable BMI. In terms of Hazard Ratio (where HR of 1 = BMI 20-25), BMI of 25-30 had a HR for all cause mortality of 0.94 (lower; CI 0.91-0.96). BMI 30-35 had HR 0.95 (lower; but CI 0.88 – 1.01 NS). BMI 35-40 HR 1.29 (higher CI 1.18-1.41). In other words – overweight patients had LOWER all cause community mortality than BMI 20-25. Being obese up to BMI 25 did NOT increase mortality risk, and only individuals with BMI >35 had increased risk.
People – you need to face up to it: OVERWEIGHT IS THE NEW “NORMAL.” Perhaps “Chubby Chandler (above)” was the healthy one.
More comments to follow.