In the medical field, body mass index (BMI) is the number that is used to assess your physical health. The calculation, which divides your weight in kilograms by the square of your height in meters, determines whether you classify as underweight, normal weight, overweight, or obese.
Why is BMI the global diagnostic “golden standard?” As the World Health Organization explains, “As BMI increases, so does the risk for some common conditions related to overweight and obesity: premature death, cardiovascular diseases, high blood pressure, osteoarthritis, some cancers, and diabetes.”
Similarly, research has shown that weight loss can help improve some biomarkers. For example, overweight individuals can increase their HDL (“good”) cholesterol by 1 point for every 6 pounds they lose. One
While a body of scientific literature supports the use of BMI, it falls short in some areas. There are valid reasons why it should not be the only factor considered in a health assessment.
One vital piece of information BMI does not take into consideration: body fat percentage. Some body fat is needed to protect vital organs, cushion joints, and transports fat-soluble vitamins. But having more fat stored around the organs in the abdominal area, instead of around the hips and under the skin, is associated with an increased risk of developing heart disease and type 2 diabetes. According to the American Council on Exercise, a body fat percentage of 14-20% for females and 6-13% for males is classified as that of an athlete, while anything above 32% for women and 25% for men falls into the “obese” category.
Since BMI calculations only factor in height and weight, lean but very muscular individuals can be incorrectly categorized as overweight or obese. The same can happen with pregnant women. A woman of average weight will gain anywhere from 25 – 35 pounds throughout her pregnancy, which is why only the pre-pregnancy weight should be used to determine BMI. Finally, older people who have lost muscle mass may be overfat but underweight by BMI standards.
This brings us to a more important point about our society’s focus on weight in general. When discussions on health center focus exclusively on weight, other important factors are often inadvertently left out of the conversation.
And, there is plenty of crucial information we can’t gather from BMI only. This calculation does not provide insight into our heart and cardiovascular health and fitness, vessel health, or our body’s ability to regulate blood glucose. After all, it’s possible to not surpass caloric needs while subsisting on a diet rich in highly processed foods and empty calories.
Consider the following: from a strictly numerical standpoint, there is technically no difference between 200 calories of candy and 200 calories of Granny Smith apples with almond butter. However, those two snacks’ drastically different nutritional profiles have drastically different effects on our health.
The apples offer health-promoting vitamins, minerals, and phytonutrients along with fiber, which helps lower heart disease and type 2 diabetes risk. The candy, meanwhile, is a perfect example of “empty calories” and offers a generous amount of added sugar, which can increase blood pressure and triglycerides while negatively impacting protective HDL cholesterol. Additionally, the health benefits of monounsaturated fats in almonds have been
A growing body of evidence also makes the increasingly compelling argument that fitness level needs to be taken into account:
“Regular aerobic exercise may not lead to weight loss, but it does reduce fat in the liver, where it may do the most metabolic damage, according to a recent study at the University of Sydney.”
While health is mostly a numbers game, one number alone does not determine the state of our health. Apart from weight, we need to look at blood pressure, cholesterol, blood sugar, liver enzymes, and kidney function. There are also other criteria worth keeping in mind: how do we feel after exercising for 15 minutes? How is our gastrointestinal health? How are our energy levels? How do our skin, hair and nails look?
Let’s also remember that BMI is not a reflection of self-worth. There are many other ways to measure health and track progress.
If you are now able to run for an additional five minutes, have replaced soda with water as your go-to beverage, and are making more home-cooked meals than you were this time last year, you are taking the right steps toward improving your health. If the scale also shows a downward trend that also lines up with you feeling better overall, that’s great. Just remember you are more than a number.