DEXA Scan
Dual-energy X-ray absorptiometry, or DEXA, is a low energy X-ray test that allows for an instantaneous snapshot of your total body composition. DEXA has traditionally been used by healthcare providers to measure bone density, but measures of lean muscle mass and adipose (fat) tissue can provide important insights into risk of metabolic syndrome, cardiovascular disease, and chronic inflammation.
DEXA scans will report a variety of specific measurements, including body fat percentage, lean tissue, asymmetry in muscles, and others. While all of these are useful, there are 3 key measures that are especially important to guide your care:
Appendicular lean mass index (ALMI) which is a measure of the skeletal muscle mass in your arms and legs, relative to your height. ALMI can tell you if you need more protein and strength training to ensure that you have enough muscle mass - an important parameter for longevity, prevention of frailty, and metabolic regulation.
Visceral adipose tissue (VAT) mass calculate the amount of dangerous, inflammatory fat that can deposit and wrap around internal organs, causing fatty liver disease, kidney damage, insulin resistance, and other chronic illnesses. Even in individuals with a normal BMI (i.e., apparently little fat), the amount of VAT may be dangerously high, a phenomenon known as “TOFI” (thin outside, fat inside).
Bone mineral density is an important measure of skeletal health and mineralization. A number of chronic illnesses, as well as low testosterone or estrogen levels, can result in bone density loss, otherwise knowns as osteopenia. Prevention of osteopenia, and osteoporosis which comes later, is critical to prevention of injury and frailty later in life.
A DEXA scan takes only minutes and provides a variety of measures - a customized report allows you to understand your entire body composition in detail. Your parameters can be compared to other individuals of the same sex and age and followed longitudinally with repeat DEXA scans after improvements in body composition.
Ideally individuals will minimize their VAT mass (the especially problematic type of fat) to below the 10th percentile for people of the same sex and age and increase their lean muscle mass to above the 90th percentile. To achieve this, most individuals need a combination of nutritional changes (reduced calories but an increase in lean protein) as well modifications to training and exercise (combination of strength and endurance training).
