You know the saying: You can never be too rich or too thin. Go for rich, but forget about too thin. Why? Results of a recently published study which examined the relationship between being underweight and dying found that being underweight puts people at highest risk of dying -- just as obesity does.
The study, led by Dr. Joel Ray, a physician-researcher at St. Michael's Hospital and the hospital's Li Ka Shing Knowledge Institute, was published this week in the Journal of Epidemiology and Public Health. It's well known that people with high BMIs are at a greater risk of illnesses including diabetes, heart disease and hypertension, but there's always been an assumption that the lower your BMI the more you are protected from such illnesses. Thin is not only in, it's considered, at least by many people, to be healthier than being overweight.
But is this the case?
Dr. Ray's meta-analysis looked at 51 studies on the links between BMI or body mass index (a popular measurement tool for obesity) and deaths from any cause. He found that adults who are underweight -- with a BMI under 18.5 or less -- have a 1.8 times higher risk of dying than those with a normal BMI of 18.5 to 24.9. The risk of dying is 1.2 times higher for people who are obese (BMI of 30 to 34.9) and 1.3 times higher for those who are severely obese (a BMI of 35 or more.)
Thin as something to aspire to is everywhere around us, from celebrity photos to reality shows, from the constant barrage of diet books to monthly "lose-it" articles in women's magazines and size zero clothes. The fact that we try desperately to lose weight is also reflected in a weight loss industry that in 2013 tipped the the scale at over 61 billion dollars.
We all know that to lower our risk of some conditions and diseases the advice given is usually to drop some pounds. But many of us take dieting too far and forget that there is a difference between lean and skinny, the former a reflection of robust health and fitness, the latter frankly potentially unhealthy and frankly unattractive. "Excess thinness is not the road to health, and not the road to robustness," Dr. Ray told me. "Think of health robustness as decent muscle structure, reasonable fat, and good bone structure -- all generated by moderate eating. That's sufficient eating, not overeating or undereating."
"BMI reflects not only body fat, but also muscle mass," he told me. "BMI measures a person's bones, muscles and fat as the contribution to body mass. It may take into consideration their tallness or vertical framesize, too." Dr. Ray suggests that if BMI is going to be used as a measurement tool, then we should realize that someone who is healthy has "a reasonable amount of body fat and also sufficient bone and muscle."
If BMI continues to be used as a focus for "our fetish on body fat," then it should be replaced with other measurement tools such as waist circumference which co-relates heart disease and diabetes risks, or even the weight scale. For example, abdominal fat is harmful fat and increases cardiovascular risk; however, people who have fat distribution in the lower hip or buttock area do not have a higher mortality risk. Body composition, he says, depends on more than our infatuation with avoiding overweight states.
Society is currently focused on curbing the obesity epidemic -- and rightly so. But the risks of being underweight have been neglected by this focus on obesity, says Dr. Ray. "As we slide society away from obesity, we must be careful we don't slide people who are of normal body composition into excessive thinness or into an underweight state through undereating."
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