Stop looking at the scale: Why Bodyweight Doesn't Predict your Health or fitness
Discouraged that you’re not losing weight despite your efforts in the gym? Don’t be. Your cardiovascular, metabolic and overall health will often times improve despite little to no change in body weight.
The societal obsession with body weight has long been used as a primary indicator of a person's overall health and well-being. This belief has led to the proliferation of fad diets and extreme exercise routines and perpetuated weight stigma and discrimination. However, peer-reviewed literature challenges this notion and supports that body weight or body mass index (BMI) is not the ultimate predictor of health; other factors provide much better insight into an athlete's health and performance status. In this article, we will explore the BMI, why body weight does not correlate with overall health, and highlight alternative indicators for a comprehensive understanding of overall fitness.
Body mass index
The body mass index (BMI) has its roots in the 19th century when Belgian mathematician Adolphe Quetelet developed the Quetelet Index to assess an individual's body size relative to their height. The modern term "body mass index" was coined in the 1970s by American scientist Ancel Keys, who sought to create a simple, standardized measurement for assessing obesity on a population level. Insurance companies quickly adopted BMI as a tool for determining health risks and calculating premiums, as it offered an easy, cost-effective method to evaluate an individual's potential risk for various health conditions. However, as our understanding of health has evolved, it has become increasingly clear that the relationship between BMI and overall health is more complex than initially believed. Consequently, reliance on BMI as the sole determinant of health risk has come under scrutiny, with researchers and healthcare professionals emphasizing the importance of considering additional factors, such as cardiorespiratory fitness, dietary habits, and mental health, when evaluating an individual's overall well-being.
Body Weight as an Insufficient Health Predictor
The BMI is not an accurate indicator of overall health. In a study published in the International Journal of Obesity, researchers examined the health data of over 40,000 adults. They found that nearly half of the participants considered "overweight" by BMI standards were, in fact, metabolically healthy (Tomiyama et al., 2016). This study highlights that relying solely on body weight can lead to misconceptions about an individual's health status. An excellent book entitled “Big Fat LIes” by Professor Glenn A. Gaesser from the University of Arizona further showcases the fallacies of using body weight as a predictor of health and mortality. I highly recommend the book and have used it in my upper-level undergraduate and graduate courses to discuss the fallacies of using body weight as a means to predict health and performance.
Cardiorespiratory Fitness: A Better Indicator
Instead of focusing on body weight, cardiorespiratory fitness (CRF), also known as VO2 max, has emerged as a more accurate predictor of overall health. CRF is a measure of the body's ability to supply oxygen to muscles during physical activity and is typically assessed through aerobic exercises like running, swimming, or cycling. A study published in the Journal of the American College of Cardiology demonstrated that individuals with higher CRF levels had lower risks of cardiovascular disease and all-cause mortality, regardless of their BMI (Barry et al., 2014). The researchers concluded that improving CRF levels is more important for health outcomes than focusing on weight loss alone. This is just one example of the thousands of peer-reviewed investigations linking high CRF to reduced mortality and morbidity and improved quality of life. These tests are typically performed in a laboratory setting with a trained individual to perform the test and help interpret the results. Our Coaches can help you find a qualified laboratory to complete a CRF test and help you use the results to guide your endurance training.
Glucose Regulation
Body weight is a poor predictor of glucose regulation or what has also been termed “metabolic fitness.” Glucose regulation is the body's ability to maintain stable blood sugar levels, which is essential for preventing type 2 diabetes and related complications. Type 2 diabetes results in an inability for insulin to bring glucose into the cell. This results in hyperglycemia (high blood sugar), which causes microvascular function degradation and tissue damage. With regards to body weight, CRF, and glucose regulation, a study in the Journal of Clinical Endocrinology & Metabolism found that overweight and obese individuals with high CRF levels had similar or better glucose regulation than their normal-weight counterparts with low CRF levels (Wei et al., 1999). This study indicates that improving physical fitness, rather than merely losing weight, can lead to better glucose regulation. Although many patients improve their resting glucose values after taking on an active lifestyle, because the scale doesn’t show a loss in body weight, physicians will often miss the win and further counsel the patient on their lack of weight loss. This wreaks havoc on a patient’s overall outlook on their health and well-being and often leads individuals to take on extreme diets in the hopes of attaining the weight loss goal set by the physician.
Other Factors Affecting Overall Health
It is essential to recognize that overall health is a complex interplay of various factors beyond body weight, such as genetics, diet, physical activity, mental health, and sleep quality. Some peer-reviewed sources suggest that focusing on weight-neutral approaches, emphasizing health-promoting behaviors regardless of weight, can lead to more sustainable and positive health outcomes (Tylka et al., 2014).
For instance, adopting a balanced diet rich in fruits, vegetables, whole grains, lean protein, and healthy fats can improve overall health and reduce the risk of chronic diseases. Regular physical activity, such as brisk walking, swimming, or yoga, not only enhances cardiorespiratory fitness but also contributes to better mental health, stress reduction, and improved sleep quality.
Mental health is another crucial aspect of overall well-being that should not be overlooked. We now understand that individuals who experience weight stigma, body dissatisfaction, or disordered eating patterns may be at a higher risk of developing mental health issues, such as depression and anxiety (Puhl & Suh, 2015). Fostering a more inclusive and compassionate environment that focuses on health-promoting behaviors rather than weight loss can help improve mental health and overall well-being. Getting people to be more physically active should be at the core of this movement and will help prehabilitate individuals to deal with the stresses of aging and other impediments to overall health and longevity.
Conclusion
Despite popular belief, body weight and BMI are poor predictors of overall health. Interventions that increase energy expenditure and improve diet often result in improved blood glucose regulation and blood pressure, despite an absence of weight loss. Focusing on improving physical fitness, adopting a balanced diet, prioritizing mental health, and maintaining quality sleep can lead to better health outcomes. By shifting the conversation from weight to health-promoting behaviors, we can create a more inclusive and supportive environment that promotes sustainable and positive changes for individuals of all sizes.
References
Barry, V. W., Baruth, M., Beets, M. W., Durstine, J. L., Liu, J., & Blair, S. N. (2014). Fitness vs. fatness on all-cause mortality: A meta-analysis. Progress in Cardiovascular Diseases, 56(4), 382-390.
Puhl, R. M., & Suh, Y. (2015). Health consequences of weight stigma: Implications for obesity prevention and treatment. Current Obesity Reports, 4(2), 182-190.
Tomiyama, A. J., Hunger, J. M., Nguyen-Cuu, J., & Wells, C. (2016). Misclassification of cardiometabolic health when using body mass index categories in NHANES 2005-2012. International Journal of Obesity, 40(5), 883-886.
Tylka, T. L., Annunziato, R. A., Burgard, D., Daníelsdóttir, S., Shuman, E., Davis, C., & Calogero, R. M. (2014). The weight-inclusive versus weight-normative approach to health: Evaluating the evidence for prioritizing well-being over weight loss. Journal of obesity, 2014.
