BMI — Body Mass...What?

We have all heard the term BMI, but do we know what that means, how to calculate it and whether it’s a good indicator of health status? Nutrition for Longevity is here to break it down for you.

What Is It?

BMI is our Body Mass Index. It is a measure of body fat based on height and weight.¹ In English measurements, it can be calculated as follows: weight (lb) / [height (in)]2 x 703.² With that number, you are able to determine your weight category. A BMI less than 18.5 is considered underweight.¹ A BMI of 18.5–24.9 is considered normal.¹ Overweight is defined as 25–29.9.¹ A BMI of 30 or greater is considered obese.¹

Pros of BMI

A positive of BMI is that it is a quick and easy way to determine weight status. In just a minute, a person can do the calculation on their own and see which category they fit into. At the doctor’s office, the doctor can quickly determine BMI and make a certain recommendation based on the results. A significant number of studies has shown that a high BMI predicts a higher risk of chronic disease.³ There are no costs or expenses associated with calculating BMI. It is simple and straightforward. These days, most of us are looking to simplify things, especially when it comes to our health.

Cons of BMI       

While a pro of BMI is that it is simple, a con is that it may be too simple. BMI does not take into account body composition. Muscle weighs more than fat, so if a patient has a lot of muscle the BMI will not be accurate.⁴ For example, if a person is very muscular with little body fat, they may register a BMI over 30. Yet it would be clear that this person is not obese. In the reverse situation, someone with little muscle and higher levels of fat could have a normal BMI, but this person could be at risk of cardiovascular disease.

BMI also does not factor fat distribution and the type of fat. Excess fat around the stomach in particular has been linked to heart disease.⁴ There are two types of abdominal fat. Subcutaneous fat is the fat that lies directly under the skin.⁴ Visceral fat is the type that is deep within the abdomen and surrounds vital organs.⁴ Visceral fat is more harmful than subcutaneous fat. It has been associated with several chronic diseases such as diabetes and heart disease.⁴ BMI also does not take into account age, gender, race, and ethnicity.

Other Ways to Calculate Body Mass      

Fortunately, there are other ways to determine body fat percentage. Waist circumference is the best way to measure the previously mentioned abdominal fat. Waist circumference is the circumference of the abdomen, measured at the natural waist (in between the lowest rib and top of the hip bone).³ Like BMI, it is easy to measure and inexpensive, but it can be difficult to measure and less accurate in individuals with a BMI of 35 or greater.³

Similar to waist circumference, there is the waist-to-hip ratio. It is determined by measuring the waist and the hip, then dividing the waist measurement by the hip measurement.³ Waist-to-hip ratio is also a simple calculation yet it may be prone to error because it requires two measurements. It is also more difficult to measure the hip than the waist.³

Then there is the skinfold thickness. This method involves measuring the thickness of a “pinch” of skin and the fat beneath it in certain areas of the body, like the trunk, thighs, front and back of the upper arm, and under the shoulder blade.³ This method is also simple and inexpensive, yet not as accurate as other systems. Perhaps the simplest measure of getting a pulse on your weight status? A pair of jeans! How they fit now compared to last year is a good way to measure any changes in your body.

Other Ways to Determine Health Status

Aside from body mass, there are countless other biomarkers to assess your health. Those yearly doctor visits are essential to figure out what is going on inside the body. A familiar and routine check is the blood pressure. According to the American Heart Association, high blood pressure is a “silent killer.”⁵ High blood pressure (HBP) is a significant contributing factor to heart attack and stroke.⁵ Getting your blood pressure checked is the best way to know whether your blood pressure is high.

In addition to blood pressure, there are certain blood tests that are worth paying particular attention to. A high level of glucose (sugar) in the blood is a key indicator of Type 2 diabetes.⁶ Type 2 diabetes can lead to heart disease, kidney failure and even blindness in severe cases.⁶ Lipid levels measure the levels of fats in your blood.⁶ Total cholesterol, LDL (bad) cholesterol, HDL (good) cholesterol, and triglycerides are evaluated with a blood test known as a lipid panel or profile.⁶ Risk of heart attacks and strokes often depend on lipid levels in the blood.

Other ways to gauge your health status that do not require a visit to the doctor include counting your movement throughout the day and hours of sleep. According to the Physical Activity Guidelines for Americans, 2nd edition, adults should achieve at least 150 minutes to 300 minutes a week of moderate-intensity, or 75 minutes to 150 minutes a week of vigorous-intensity aerobic physical activity.⁷ In terms of sleep, the recommended amount for adults is 7 hours or more.⁸ If you need help holding yourself accountable, grab a journal and log both your amount of activity and hours of sleep in order to make them a priority.

Key Takeaways

While BMI is a good starting point, it should not be the only measure used in determining health status. As we have learned, it does not take into account important factors such as body composition, type of fat, gender, ethnicity, etc. The other methods listed should also be utilized to determine the most accurate measure. And the absolute easiest way to know your health is on the right track? Fuel your body with delicious, nutritious food! At Nutrition for Longevity, it’s what we eat that is of the utmost importance. This Mason Jar Salad recipe is perfect for a quick and easy weekday meal. Or prioritize eating with purpose with our selection of healthy meal plans that are perfect for vegans, pescatarians, and flexitarians!