Body Weight And BMI Have Limitations When Striving For Longevity Health
In conventional medicine and the popular press, body weight is a health parameter that is essential for assessing our overall health. Another metric that is universally calculated and placed in the medical chart is the “BMI”, or body mass index. However, these parameters are not necessarily the “healthy bar” that we imagine. Many larger athletes and other fit people have a higher than average BMI, but have very low body fat and high muscle, and therefore are extremely fit. Christine Ohuruogu, an Olympian silver medal sprinter for the UK, has a BMI of 27, which on an insurance table would be “overweight”. However, she has very low body fat and is extraordinarily fit and highly muscled. One glance at her photo reveals that she is an elite super-fit athlete.
The Shift To Body Composition To Support And Track Health
Today, thanks to recent studies and advances in technology, we understand that we need to shift our focus toward understanding body composition and away from weight alone as a metric. This paradigm shift is a very crucial advance for supporting and tracking health. This blog reviews the limitations of solely focusing on weight or BMI as a health metric and introduces body composition and body recomposition (both muscle and fat compartments) as key concepts. We dive into what body composition is, how knowing your body composition can inform your health, how body composition is measured, and how we can use body composition to set body recomposition goals to better support optimal health and longevity.
Body Weight Alone Doesn’t Tell The Whole Health Story
Individuals have been hyper-focused on weight for decades, whether it is weighing themselves obsessively, basing their self-image on a scale number, or setting a goal to lose a made-up number of pounds in the name of “getting healthier”. We also see many people who fall under “normal” weight guidelines but are tremendously under-muscled, and carry excess visceral fat – we sometimes call this condition “skinny fat”. Conditioning around weight is deeply ingrained in us through advertising, media, and perhaps family upbringing, and remains all too prevalent today. We have a lot of unlearning to do, but it’s possible! The truth is that weight alone doesn’t tell the whole story of health, and more often than not, the number on the scale isn’t the best thing to focus on in terms of your health.
What Are The Limitations of Focusing On Body Weight?
While a scale shows how much a body weighs in total, it doesn’t provide any information on the amount of muscle an individual has, the amount of fat, or where their fat accumulates on their body. All of these detailed parameters correlate more directly with disease risk. Muscle and fat have different densities and different amounts of water content, with muscle tissue much denser than fat. A scale provides no delineation between the two and provides no insight into their relationship to each other. Furthermore, putting too much focus on weight alone can lead to unhealthy habits and behaviors that don’t actually support an individual’s current or long-term health, negatively affecting our relationship with food and our ability to build and maintain muscle which affects our energy and nutrient levels.
Many weight loss studies and longitudinal mortality studies are finally beginning to measure not just weight lost or gained, but also collect fat, muscle, and water data to clarify what has happened on various eating programs. What we are learning is somewhat discouraging. Many of the Semaglutide papers, which document an impressive 15-25% of “weight” lost in 1 year, show that 40% of the weight lost was MUSCLE weight. This is very worrisome, especially in a middle-aged or older adult, where regaining muscle is significantly more challenging. Consider intermittent fasting studies, which have been used to advocate for a time-restricted eating window, and also document some weight loss, but a lot of muscle loss. Since gaining and keeping muscle means avoiding frailty, and is crucial for maintaining optimal functioning and independence as we age, this tremendous loss of muscle in mid-life adults is extremely worrisome. It is quite difficult to get that muscle back. And lower muscle means the metabolic needs are lower, so this is a recipe for regaining weight as the metabolic “engine” has shrunk.
Here are two examples of the limitations of the scale:
- An individual decides to try to lose 10 pounds. They eliminate processed foods and start a consistent exercise program with resistance training and cardio. In 2 months they feel better, have more energy, and find their clothes fit better, but the scale still reads the same or even perhaps slightly more. According to the scale, no progress has been made. In reality, because muscle is denser than fat, the individual may have simultaneously added a few pounds of muscle, lost a few pounds of fat, and became healthier, but their scale does not reflect that improvement and they are very discouraged.
- An individual decides they want to lose 15 pounds for the new year. They become obsessed with tracking calories, over-restrict, and do excessive amounts of cardio to burn calories. At the new year, they reach their weight goal, but they aren’t any healthier or stronger. The scale does not reveal that they have lost a large amount of muscle, along with a small amount of fat. So they are smaller, yes, but less strong and may have the same amount of total body fat or even proportionally MORE fat tissue than before.
Body Mass Index (BMI) Is Also a Limited Metric
BMI or body mass index has similar limitations. BMI is a calculated measure of body overall mass, which utilizes a person’s current weight and height. Similar to weight alone, BMI doesn’t provide any information on muscle mass, fat mass, or body fat percentage and can be misleading in terms of health status. Many public health experts have strongly pushed the medical industry to stop using this metric to determine if someone is healthy.
A Better Way: Focus On Body Composition – Not Weight Or BMI
A better way to gauge health and support longevity is to measure and follow body composition. Body composition gives insight into metabolic health by breaking total weight into core components like fat, muscle, and body water. Changes in body composition are intimately connected to health status and risk of age-related pathologies, so measuring body composition is crucial for personalized prevention strategies related to aging. Generally, with aging, it’s common to see an increase in fat mass (specifically visceral fat) and a gradual decline in lean mass, specifically bone and muscle mass. Also, individuals with a higher body fat percentage, particularly intra-abdominal fat, have a greater risk of cardiovascular disease, type 2 diabetes, cancer, and early mortality in general.
Body Recomposition Goals to Improve Health And Longevity
Body recomposition is a newer and better goal, and a new term being used in the longevity and athletic training areas. It becomes harder to build and even just maintain muscle as we age and body composition isn’t set in stone because fat mass, lean body mass, and body fat percentage can change based on a variety of factors. What’s empowering is that we can positively alter our body composition through key factors in our control, especially our diet, exercise, and lifestyle choices. Once an individual’s body composition is measured it can be used as a baseline. From there, we can identify personalized areas of focus for goal setting related to improved health and longevity. Tracking body composition at least once or twice a year is recommended for all adults interested in maintaining health. More frequent measurements are done when we are making interventions to make things shift.
For most, body recomposition goals involve losing excess fat while also building more muscle, using personalized diet and exercise protocols, specifically a nutritious diet with adequate protein, and an exercise regimen with consistent progressive resistance training. Gaining muscle requires plenty of protein, so not enough protein or calories could actually hinder your efforts if there isn’t enough to help muscle tissue repair, rebuild, and grow. In our exercise prescription, resistance training is essential and should be added to cardio. Cardio requires a lot of energy, and while you can burn a lot of calories, you aren’t necessarily building or maintaining muscle and could be experiencing tissue and joint breakdown from excessive repetitive motion. Other factors that may influence body recomposition include sleep quality and quantity, and stress hormones. Sleep deprivation, in particular, is associated with negative hormonal changes and may hinder body recomposition efforts. Again, If your goal is to preserve muscle mass while also losing fat, your focus should primarily be on a protein-rich nutrition plan and a resistance training program.
How Do You Measure Body Composition?
There are many ways to measure body composition, with the most accurate methods requiring the help of a trained technician or doctor. If you come in a Fitness for Longevity Appointment here at Hudson Valley Longevity Medicine, our offering involves an Inbody570 test which measures over a dozen parameters, including fat mass, muscle mass, muscle mass by limb, body water, and total and visceral fat. The process for this test is quite simple and involves standing for 3 minutes on our in-office InBody Machine. Align your heels with the footplates, hold onto the handles on the sides of the machine, place your thumbs on the electrodes, and position your arms straight and away from the torso. Stand still for about a minute, and you’ll have a full body composition report to learn from, with the help of Dr. Leventhal!
Intrigued? Book A Fitness For Longevity Appointment Today!
For those intrigued and eager to apply this information on a personalized level, you can request a Fitness for Longevity appointment at Hudson Valley Longevity Medicine with Dr. Leventhal through our website here. As mentioned, part of this offering involves measuring your body composition and visceral fat through an Inbody570 test. With this test comes a full report detailing muscle, fat, and water measurements. This report will be discussed in depth during the first 2-hour consultation with Dr. Leventhal and utilized to create goals and an action plan based on your results.
Barakat, C. MS, ATC, CISSN, Pearson, J. MS, Escalante, G. DSc, MBA, ATC, CSCS, CISSN, Campbell, B. PhD, CSCS, FISSN, & De Souza, E. O. PhD. (2020). Body Recomposition: Can Trained Individuals Build Muscle and Lose Fat at the Same Time? Strength and Conditioning Journal, 42(5), 7-21. doi:10.1519/SSC.0000000000000584. https://journals.lww.com/nsca-scj/fulltext/2020/10000/body_recomposition__can_trained_individuals_build.3.aspx?ck_subscriber_id=1918138411
Holmes CJ, Racette SB. The Utility of Body Composition Assessment in Nutrition and Clinical Practice: An Overview of Current Methodology. Nutrients. 2021; 13(8):2493. https://doi.org/10.3390/nu13082493
Ponti, F., Santoro, A., Mercatelli, D., Gasperini, C., Conte, M., Martucci, M., Sangiorgi, L., Franceschi, C., & Bazzocchi, A. (2019). Aging and Imaging Assessment of Body Composition: From Fat to Facts. Frontiers in Endocrinology, 10, 861. https://doi.org/10.3389/fendo.2019.00861
InBody: 9 Body Composition Myths, Busted
Body fat and risk of all-cause mortality: a systematic review and dose-response meta-analysis of prospective cohort studies: https://www.nature.com/articles/s41366-022-01165-5 Lowest overall mortality risk at 25% body fat in a group of middle to older adults