Since Adolphe Quetelet developed the Body Mass Index (BMI) system in 1832, it has become a standard choice when determining a person’s health. Over the years, many experts have raised concerns about this way of measuring health because it only takes into account weight and height. A new study now says we should avoid relying on BMI and focus more on cardiovascular fitness to accurately understand our own health.

Cardiorespiratory Fitness and Cardiovascular Disease

The study, which was published in the British Journal of Sports Medicine, focused on understanding the relationship between health measurements and mortality.

The researchers used two health measurements. This consisted of cardiorespiratory fitness and Body Mass Index. All-cause mortality risks were analyzed, including the likeliness of developing cardiovascular disease.

Studies published from 1980 up until 2023 were reviewed, with a total of 20 articles selected by the researchers. The studies included in the analysis were able to provide data surrounding 398,716 individuals, giving researchers plenty of records to work with.

Researchers found that the relation between BMI and all-cause mortality was much less significant compared to cardiorespiratory fitness. Those with a BMI that fell into the categories of overweight or obese but were fit overall didn’t have a significantly higher risk for all-cause mortality or cardiovascular disease.

However, researchers were able to determine that those with a high BMI and a low cardiorespiratory fitness rate had a higher risk of cardiovascular conditions and all-cause mortality.

The findings of this study show us that BMI alone is not an accurate way to measure health. Instead, primary care providers should consider looking at a patient’s cardiorespiratory fitness by measuring VO2 Max. This can help predict the risk of disease with greater accuracy.

Understanding BMI and VO2 Max

While assessing the findings of this study, it’s important to start with a good understanding of what BMI and VO2 Max mean.

First, let’s consider BMI, also known as Body Mass Index. It is a rating that gives you an idea of your body weight. The measurement relies on the height and weight of your body.

A BMI between 18.5 and 24.9 is generally considered normal. If a person’s BMI is between 25 and 29.9, they are considered overweight. Obesity starts at a BMI of 30. However, it’s interesting to note that BMI often classifies individuals with high muscle mass, like athletes, as “obese,” which is vastly inaccurate.

VO2 Max doesn’t take into consideration body mass, which includes both fat and muscle. Body mass can be misleading based on the exact breakdown of fat vs. lean. Instead, VO2 Max is a technique that directly measures the cardiovascular and respiratory fitness of the body. It is a measurement that considers the maximum oxygen utilization of your body at a peak level of physical activity.

Measuring Your VO2 Max

Body weight scales and recent technology have made things much easier when it comes to understanding your BMI. However, the process of determining your VO2 Max often requires a visit to your doctor’s office or a fitness center. Fitnescity can help you identify these locations.

During this process, you’ll be given a mask to wear. This mask, along with the VO2 Max machine, is used to determine how much oxygen you take in and the amount of carbon dioxide that you breathe out. The equipment also provides details about the amount of oxygen you breathe out. You will be asked to perform an exercise, such as running, cycling, or rowing, in order to determine how much oxygen your body is able to use.

The exercise session generally starts out at a low intensity. However, after a warm-up period, the test provider will start to increase the intensity of the exercise, whether this involves riding on a stationary bike or running on a treadmill.

The intensity is increased until you reach your peak. This is the maximum intensity level that you’re able to comfortably keep up with.

The test provider will then monitor the results of the machine connected to the mask you wear. This allows the professional to get a better idea of the maximum oxygen your body uses relative to your weight (in ml/kg/min) when it is exercising at a peak intensity level. The higher this number, the greater your cardiovascular fitness.

The expert will then take into consideration factors like age and sex to determine where the results fall. For example, for a man aged 30, a good VO2 Max rating would be between 49 and 56. Anything over 56 at this age is considered excellent.

Concerns about cardiorespiratory fitness come into the picture when the results for this 30-year-old man go below 49, as then the VO2 Max level is not considered good.

Conclusion

Emerging evidence suggests that BMI is not necessarily the best method to measure health, and that cardiorespiratory fitness should be used instead. The evidence shows a significant link between cardiorespiratory fitness and all-cause mortality. While it does take more effort to do a test for cardiorespiratory fitness to measure VO2 Max, the potential that lies in this vital sign can be extremely useful.

References

https://pmc.ncbi.nlm.nih.gov/articles/PMC10693914/

https://bjsm.bmj.com/content/early/2024/11/07/bjsports-2024-108748