BMI has been somewhat overinflated for two reasons. First, it is possibly the easiest and cheapest measurement a researcher or health provider can take other than age. Second, it reliably predicts the risk of developing heart disease, diabetes, or knee osteoarthritis in adults. All of those can be prevented or delayed, to some extent, by lifestyle interventions. Recognizing risk and taking action can improve quality of life. On the other hand, a healthy BMI does not mean that you eat enough fruits and vegetables, or that you have strong bones and clean arteries. Nor does it mean you have a healthy relationship with food. Healthy, very active people can also be relatively muscular with a technically “overweight” BMI that reflects high mucle weight rather than fat weight. BMI is a generalization, not a perfect predictor.
BMI in kids is less accurate, but still somewhat useful. Should we be weighing kids in schools and putting it on their report cards? Well… I always thought the scoliosis exams were crazy embarrassing, so my impulse would be to say no. Should we be weighing kids at the doctor’s office? Definitey. You don’t really know if your child is off or on the growth chart, or if their percentile changed significantly, without checking. The BMIs and diets of teenagers have also been associated with increased risk of type II diabetes as adults. Monitoring basic stats and recommending healthful diet changes is sensible preventative medicine. If a weight check can cause an MD or nurse practitioner to nudge a few parents and kids away from soda and chips towards water and strawberries, that’s a good thing. Should kids care about their BMI? Probably not. BMI shifts with age and development, and it’s supposed to.
Obesity marks risk of health problems; however, BMI is not a perfect predictor of obesity. Normal BMI definitely does not guarentee a healthy diet. Neither should be treated as the single measurement needed to evaluate the health and diet of Americans. Given this nation’s persistent inability to eat real food, public health and community-based food projects must be designed to reach out to all who need nutritional assistance. Narrowly defining our national nutrition problem as overweight and obesity disregards many facets of food and health, and misses the opportunity to prevent a multitude of issues ranging fron dental health and eyesight to eating disorders and premature births. We should all eat well, regardless of height, weight, age, or any other factor. Safe, healthy food is a basic human right that our nation needs to embrace.