The Perfect Human Size (according to science!)

It's common knowledge that one's physical fitness is generally a good indicator of his or her health. People who are overweight are at many heightened health risks, when compared to their fitter counterparts, including: heart attack, stroke, joint/muscle pain, and numerous others, including cancer. Indeed, in the wonderful presentation from last Friday about the risk factors of pancreatic cancer, diet and obesity were two of the main points that were presented. Thus, when I read one particular article by the NIH, entitled, "NIH study identifies ideal body mass index;  Overweight and obesity associated with increased risk of death", my interest was piqued. I think that having a  
specific goal that people can shoot for is wonderful- having a target like, "losing five pounds of fat" is usually much more feasible and effective than an abstract goal, like "getting in shape."

 From http://www.stampscommemorative.org/wp-includes/images/964fitness-cartoon-052108.jpg

 Via analysis of data collected from 19 long-term studies, researchers concluded that "a body mass index (BMI) between 20.0 and 24.9 is associated with the lowest risk of death in healthy non-smoking adults. As the chart to the right shows, this range is within the "normal weight" BMI range. For those who don't know, BMI is a ratio of weight to height, measured in weight in kilograms divided by (height in metres)². Calculate your BMI here! As one progresses
down the chart, health risks progressively increase, with the classes of obesity often giving rise to diabetes, heart disease, high blood pressure, gallbladder disease and many forms of cancer. Conversely, having a BMI in the "Underweight" class can lead to osteoporosis, undernutrition, eating disorders, and other health issues.

From http://www.nhlbi.nih.gov/health/public/heart/obesity/lose_wt/risk.htm

Clearly, this should raise concern for the general American population. The most recent data published by the CDC (from 2008) shows that 68% of adults in the US are overweight, with half of those overweight adults being classified in an "obese" category, according to their BMI. Younger Americans are affected as well, but not as severely: 18% of adolescents age 12-19, 20% of children 6-11, and 10% of children 2-5 are obese. Simply put, these percentages are much too high. For the large majority of people, diet and weight are completely controllable aspects of lifestyle. It is one's personal responsibility to maintain healthy habits, and they owe it to themselves, their family, and those who care and depend on them. There are some people who are predisposed to obesity due to disease, like hyperthyroidism or Cushing's syndrome, which makes it near-impossible to control weight gain. Additionally, many people don't have enough disposable income to purchase healthy foods, which can lead to poor health. Outside of these cases, weight gain is something that everyone can and should control.

I do have one qualm with this study, however. BMI is a measurement of weight and height, and fails to take into account bone density, body fat %, or muscle mass. Take Lebron James, for example- one of the best athletes in the world, with a body fat under 8% and incredible physical fitness. At his current height and weight (6'8", 250 lbs), he has a BMI of 27.5.


From http://healthhabits.files.wordpress.com/2009/05/lebron-muscle.jpg
By standard BMI categories, Mr. James is considerably overweight, and should have health concerns based on his weight! Clearly, this isn't the case, and is a perfect example of the BMI's imperfectness. For the most of the world, the BMI is a decent measurement of the healthiness of one's weight. However, for many others, other measurements should be taken into account- body fat %, waist-to-hip ratio, and body shape (apple vs pear). However as a good general rule, one should consult his or her doctor if s/he finds that her BMI is in the overweight or obese range, and see what personalized medical expertise has to say.