Written by: Christina Lim, NASM-CPT,CES @tinaroni
We are excited to announce that Custom Fit now has a DEXA scanner in-house! This is an innovative, comprehensive, highly accurate, and useful body composition measurement system that can be used to monitor not only body fat percentages and lean muscle measurements, but also distribution of fat types and bone mineral density (BMD). In this article we’re going to introduce the technology and its uses, including weight loss, “bulking” or gaining muscle, assessing visceral fat levels (the kind we don’t want), and osteoporosis risk.
Body Composition as a Marker for Disease Risk and Progress Tracking
Recent studies have shown that the risks of all-cause mortality are significantly tied to body composition. Knowing our lean mass measurements, body fat percentage levels, and fat distribution throughout the body is extremely valuable information that can help us to monitor our health, prevent disease, and maintain vitality throughout our lifetime. And as we undergo a periodized training program or nutritional program, we are also able to use intermittent body composition measurements as tools for tracking progress, especially when we’re targeting certain body fat levels or muscle gains, so that we can use the results to adjust any variables - such as nutrition, rest, and exercise - accordingly.
It’s why we’ve always ensured that there’s an opportunity to measure your body composition here at the gym. Although you might be able to plainly see a certain amount of changes in your own body over time, or notice how your clothes fit differently, the numbers don’t lie. Having a concrete report also serves as a motivational tool, visually showing potential areas for improvement, and by informing a customized nutrition and fitness program.
Newer body scanning technology furthers this capability of reading your body composition by going deeper, discerning what types of body fat are present (there are essential and non-essential, less desirable types of fat), as well as determining your bone mineral density (BMD) - which can provide indicators for osteoporosis, as well as fracture assessment and risk. These tools further our ability to assess skeletal and metabolic health.
Introducing the DEXA Scan
The DEXA body scanning machine, widely considered the gold standard for body composition testing, encompasses all of these capabilities in one system, capturing dual x-ray absorption data for each image pixel, accurate to +/-1.5% error, and in one 6-minute scan, collects all of the necessary data to provide a detailed body map and numerical readout of lean muscle mass, body fat percentage (including fat types), and bone density levels, both overall and segmentally, within each body part. It is able to recognize the detailed anatomy of the body, including subcutaneous fat, for example, or the inner abdominal muscle wall, as well as the visceral cavity of the body.
The body composition report, in addition to providing lean mass (differentiating between muscle, body water, internal organs, and connective tissues), fat mass, and bone mass measurements, provides waist to hip ratio, ideal weight, basal metabolic rate (BMR), and total caloric expenditure, which can assist with nutritional planning. The reports also provide a percentile ranking of body fat percentage, lean muscle percentage, and visceral fat against the National Health and Nutrition Examination Survey (NHANES) database of age, gender, and race matched norms.
In addition, the DEXA scan can help you see if there are asymmetries present between the left and right sides of the body, any imbalanced limb lengths, and if there are indicators of overtraining or relative energy deficiency syndrome (REDS) - which cause reduced training response, decreased coordination, impaired judgment, and increased irritability and depression.
This system was traditionally used in radiology clinics at universities and labs to assess bone mineral density for aging populations, and more recently it has been developed to provide body composition measurements that are useful for athletes and non-athletes alike in the pursuit of health and fitness assessment, sports performance, mitigation of injury risk, and longevity.
How It Works
DEXA (Dual x-ray absorptiometry) works by emitting two low-dose x-rays which are absorbed differently by bones and soft tissues. The radiation emission is less than 0.1 uSv, which is less than 1/80th of the natural background radiation you would receive in a day from natural elements like sunlight and soil, which is around 8 uSv.
As you can see from the chart below, the radiation is significantly less than that of a dental or chest x-ray.
A Weight Loss Tool and Health and Fitness Tracker
The DEXA scan is safe for all adults, however it is contraindicated for women who are pregnant or may be pregnant (as with a regular x-ray). If you have had other imaging procedures in the past 14 days, you may have been given a contrast media which could affect your scan results, so it may be best to wait until two weeks have lapsed.
Having a DEXA scan is a great way to establish a baseline before starting a new exercise or nutrition program. They’re recommended for people who are looking to lose weight, gain muscle, rehabbing an injury (you could compare left and right sides of the body for leg injury, for example), wanting to assess osteoporosis risk, or generally wanting a health assessment, as it can highlight relative health risk. Intermittent scans can help monitor visceral fat levels to keep them low, as well as muscle growth and fat loss, especially when assessing progress against specific goals.
You may want a tailored nutritional strategy for specific diets such as Keto, Zone, Paleo, Low-carb, Bulking, etc. Based on your DEXA scan, a customized recommendation can be developed by a nutritionist or dietitian, to prescribe nutrient-specific foods and supplements for you to meet your body composition goal and boost skeletal health/bone density.
The same can be done in a customized training program that focuses on, for example, core strength and functional fitness, in order to support healthy levels of lean muscle mass, bone density, and body fat.
Scans are typically recommended to be spaced apart about 12 weeks to allow the body enough time to go through physiological changes in muscle and fat mass that are detectable to the scanner. Note that your nutritionist, dietitian, personal trainer, or coach may have a specific recommendation for you.
Visceral Fat vs Subcutaneous Fat
The DEXA scan differentiates between subcutaneous fat, which acts as stored energy, and visceral adipose tissue (VAT), which accumulates in our abdomen and around organs, and is a metabolically active, pathogenic fat that releases inflammatory proteins that can contribute to heart disease, hypertension, and cholesterol abnormalities over time. High levels of visceral fat are oftentimes found in cases of fatty liver, insulin resistance, and elevated glucose levels.
In fact, visceral fat is considered to be the largest endocrine (hormone-producing) organ in the body. Since we commonly see inflammation alongside pathologic processes such as atherosclerosis, dementia, Alzheimer's, cancer, and many chronic diseases, reducing visceral fat can significantly mitigate disease risk.
What’s more, visceral fat may not be seen. A person could be what’s called TOFI (“thin outside, fat inside”) and have generally low body fat levels, but carry high levels of visceral fat deep inside the abdominal cavity. Equally noteworthy is the fact that visceral fat also increases when body fat accumulates, so it is important to consider healthy body fat levels overall.
In this way, understanding measurements of different types of body fat and where they are distributed on the body serve as an indicator for disease risk. For example, even normal weight individuals with a healthy BMI (body mass index) can have significant amounts of visceral fat and insulin resistance, thereby increasing the risk for cardiovascular disease and diabetes. Thankfully, the DEXA scanner can help us to see some of these additional potential risks.
Ready for Your Scan?
We’re excited to start providing more detailed body composition reporting and customized recommendations for everyone at Custom Fit. Please schedule your appointment using our DEXA scan appointment system online - found here.
If you’re getting started with exercise and planning meals after taking a hiatus, we get it - it can be overwhelming! Feel free to reach out using our Contact Form and the team at Custom Fit SF will set you up with a personal trainer, coach, registered dietitian, or nutritionist to best meet your needs.
About Custom Fit SF
Custom Fit SF is San Francisco’s premier personal training facility, with two studios totaling approximately 4,000 square feet. We’re located at 1844 Market Street. We have complimentary towels, a shower, lockers, air conditioning, great music, easy Muni access, street parking, and an incredible amount of natural light. Our staff is fully vaccinated, and we maintain stringent COVID-19 cleaning protocols for everyone’s safety. We’ve got an arsenal of specialized equipment ready for your personalized program. Come check us out! Fill out the intake form here.
*Disclaimer: Women who are pregnant or possibly pregnant are not advised for a DEXA scan. If you are not able to determine the safety of a DEXA scan, do not do it without having cleared it first with your physician. The suggestions included on this website are not a substitute for medical advice. You are responsible for seeking medical advice and attention as appropriate.