To Lose or Not to Lose?Thursday, March 19, 2009
Following the widely reported CanWest story by Sharon Kirkey, in which I am quoted as saying that not everyone, who meets the BMI cutoff for obesity needs to run out and lose weight, I was also interviewed by CTV on a new study, just published in The Lancet, which confirms that obesity does increase the risk of death.
This study, authored by the Prospective Studies Collaboration, examines the relationship between body-mass index and cause-specific mortality in 900 000 adults combined from 57 prospective studies – a BMI between 30—35 reduces survival by 2—4 years; at BMI 40—45, life expectancy is reduced by 8—10 years (which is comparable with the effects of smoking).
The obvious question is how to reconcile these two statements.
Here is how:
While we know that obesity increases the risk of dying, we also know that BMI is not a perfect measure of health. This is exactly why we introduced the Edmonton Obesity Staging System, where we stage obesity based on the actual presence of risk factors or comorbidities rather than on BMI alone.
The rationale for this is simple: while excess weight is certainly a health risk when it actually affects your health, in some people the health impact of even moderately excess weight appears to be minimal (see the Kirkey article). Because excess weight does not kill you in an instant and most negative health consequences of obesity, if addressed early, are reversible, you still have plenty of time to tackle the excess weight, once you have the first signs of obesity related disease – thus, hypertension, diabetes, dyslipidemia, sleep apnea, and many other health consequences of obesity are all completely reversible with weight loss (it turns out that obesity related cancers may be an important exception to this rule, as the onset of cancer may be insidious and by the time it is diagnosed, treatment may come too late – which is why I would strongly recommend that anyone with excess weight diligently follows cancer screening guidelines).
Given that weight management requires dedication and resources, and is seldom achieved in the long-term without professional help, requiring everyone to go out and lose weight even if there is no evidence of a weight-related health problem would completely “clog” the health care system. It therefore makes sense to begin addressing excess weight, when patients reach Stage 1 obesity, or in other words, develop the first signs of weight-related health problems.
Till then, the focus should be on prevention of further weight gain (a difficult enough venture) and on making lifestyle changes that include eating as healthy as possible and getting a healthy dose of daily physical activity.