In this next series of articles I am going to write about the complex and common issue of weight loss. Every day in practice I see someone who wants and/or needs to shed pounds. For some, weight loss is a cosmetic preference while for others it is a health necessity. Aside from how you feel and aside from cosmetic desires to lose weight, the most common method people (doctors and patients alike) use to determine ideal weight is the BMI (body mass index).
BMI is a simple and non-invasive way to generally measure body fat based on height and weight and it is one way for men and women over 20 way to measure relative size. It does not take into account age, sex, muscle size or bone mass. BMI does not measure fat directly and should not be used as a diagnostic tool. There are many online calculators you can use to identify your BMI. According to this method a BMI under 18.5 is underweight while 18.5 to 24.9 is normal, 25 to 29.9 is overweight and above 30 is considered obese.
According to the BMI calculation I am overweight with a BMI of 26 (most would say I am a healthy weight) and my case highlights the fact that BMI doesn’t account for bone and muscle mass. The most glaring weakness in BMI is the disconnect between the BMI label of being overweight and mortality risk. It turns out that, according to a 2006 study in Lancet and a 2010 study in the Journal of the American Geriatric Society, the lowest risk for all cause mortality (risk of dying from any cause) is for people with a BMI of 24 to 30 which, according to BMI is in the overweight range.
Having a BMI above 30 and below 24 correlates with increasing risk for dying from all causes. What I first and foremost recommend is to use how you feel to assess your weight. Secondly, I generally suggest people ignore the BMI categorization and to use the mortality data I just referenced and aim to keep their BMI between 24 and 30. Next week I’ll write more about weight and weight loss.