Hey, now you can have your cake, but before you eat it, too, you might want to think twice before driving to get it! According to a recent study conducted by the Centers for Disease Control and Prevention (CDC) published in last Wednesday's issue of the Journal of the American Medical Association (JAMA), obesity now ranks as number seven (versus its former second place rank) among the nation's leading preventable causes of death. This means that deathtrap-wise, "car crashes" might actually be ahead of a sedentary lifestyle, excess weight, and a poor diet.
Although the CDC is reluctant to make this new number official, researchers estimated the risks of mortality associated with different levels of Body Mass Index (BMI) - a number that shows body weight as it relates to height - and found that those who are obese or underweight still have an increased risk of death.
On the other hand, the study found that the group in the moderately overweight category had a lower risk of death compared to the normal group.
Why would this be? Most likely because the modestly overweight individuals who fall into the normal-to-high end of the BMI scale have improved eating habits, exercised more and have controlled their blood pressure better than in previous years. Medical care has also improved in recent years, particularly for cardiovascular disease, which may have contributed to increasing life spans.
However, a section of the discussion reads: "In many studies, a plot of the relative risk of mortality against BMI follows a U-shaped curve, with the minimum mortality close to a BMI of 25; mortality increases both as BMI increases above 25 and as BMI decreases below 25, which may explain why risks in the overweight category are not much different from those in the normal category."
So just because the overweight group had a decreased risk doesn't mean everyone in the overweight group did - the results may be skewed by those people who are in the BMI range of 25.
The reference group used in this study is a "normal" BMI (between 18.5 and less than 25). Even if we tend to believe that "normal" may be a drop too low, the "data" used in this study is just that - "data." It is made of real people in the United States with BMI's that fall into that "normal" range. The study found that people who are obese and underweight have higher mortality than those who are in that "normal" range.
Recall again that the whole purpose of the study was to measure the amount of deaths associated with being underweight (BMI less than 18.5), overweight (BMI 25 to 30) and obese (BMI greater than 30). "Normal levels" are in between those ranges.
But what is meant by "normal"? And how can it be deduced solely from a number when there are so many different body types? After all, some athletes' BMI results would indicate that they are obese, which is surely not the case. We must take into account that the BMI equation was derived in order to correlate with disease risk. BMI is not the end-all. People need to also consider many other tools.
Such tools to measure body composition include calipers (skin-fold measurement), underwater weighing, bioelectrical impedance and computerized topography. The only problem is that these methods need highly trained individuals, are not easily available to the public, and are pretty expensive!
That's not to say that those within normal range should start scarfing down another slice or two to become "overweight" - remember our new friend, Cookie MoDERATIOnster.
But then again, those deemed "overweight" on the BMI scale are not necessarily unhealthy - or even overweight, for that matter! Remember what the BMI measurement actually is. Although it seems as though it's just another outdated tool, the calculations didn't come out of thin air and have been scientifically proven to be estimates.
Note, however, that BMI does not take body composition, bone density, muscle mass or body fat into account.
The CDC emphasizes the importance of remembering that BMI is just one of many factors related to developing a chronic disease (such as heart disease, cancer, or diabetes). Other factors that may be important to look at when assessing your risk for chronic disease include diet, physical activity, waist circumference, blood pressure, blood sugar level, cholesterol level and a history of family disease.
The BMI equation may not be perfect, but it is better than using weight alone and is a more viable solution to record an entire population since the only factors one would need are height and weight. While BMI seems to be a less than optimal way of assessing these results, the study recognizes the need for more studies to be done on body composition as well.
So, next time you want to chow down at Anna's Taqueria, you might want to consider buckling up first. Oh - and of course, enjoying that spicy burrito!
Senior Marissa Beck, an English and art history major, works with the Strong Women program as an assistant manager and personal trainer for the Tufts Personalized Performance Program. She can be reached at Marissa.Beck@tufts.edu. This column is written in conjunction with Emily Bergeron, R.D., the editor of the Daily's Balance section.
