Ep. 239 - All About Body Composition & Body Fat (feat. Dr. Grant Tinsley)
Sep 11, 2023
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Dr. Grant Tinsley, researcher in body composition and leader of the Texas Tech University body composition lab, joins Iron Culture to discuss the nuances of body composition testing. Topics include bioelectrical impedance for physique sport peaking, DEXA and the six-compartment model, errors in body composition assessment, metabolism measurement and adaptation, and the future of body composition testing.
Multi-compartment models provide more accurate body composition assessment compared to individual methods like DEXA or Bioimpedance Spectroscopy (BIS).
DEXA is considered the gold standard in body composition assessment but should be combined with other methods for a comprehensive understanding.
Individual methods like Bod Pod or BIS have limitations and should be interpreted along with other measurements to enhance accuracy.
Body composition testing, including DEXA, bod pod, and bioimpedance, may have discrepancies and limitations due to factors like hydration and individual variations.
Deep dives
The Use of Multi-compartment Models for Body Composition Assessment
Multi-compartment models, including the six-compartment model, provide a more accurate assessment of body composition compared to individual methods like DEXA or the Bioimpedance Spectroscopy (BIS) technique. These models take into account various components of the body, such as fat mass, fat-free mass, bone mineral, and muscle mass, allowing for a more comprehensive understanding of an individual's body composition.
The Importance of DEXA in Body Composition Assessment
DEXA (dual energy x-ray absorptiometry) is often considered the gold standard in body composition assessment. It uses x-ray technology to measure bone mineral density, lean soft tissue, and fat mass. While DEXA provides valuable data, it is recommended to combine it with other methods, such as multi-compartment models, to get a more complete and accurate assessment of body composition.
Understanding the Limitations of Individual Methods
Individual methods like the Bod Pod or Bioimpedance Spectroscopy (BIS) have their own assumptions and limitations when it comes to body composition assessment. These methods may provide valuable insights but should be interpreted in conjunction with other measurements to mitigate errors and enhance accuracy.
The Significance of Bone Density in Body Composition
Bone density, as measured by DEXA, is an important aspect of body composition. Individuals who engage in resistance training often exhibit higher bone mineral density due to the stress placed on the bones. However, it is crucial to consider other components of body composition as well to get a comprehensive understanding of an individual's overall physique.
The Limitations of Body Composition Testing
Body composition testing, including methods like DEXA, bod pod, and bio impedance, can have discrepancies and limitations in estimating body fat percentages. Factors such as hydration, density of fat-free mass, and individual variations can impact the accuracy of these methods. It's important to understand that these tests provide estimations and not precise measurements. Even when following strict protocols, there can still be variability in the results.
The Role of Estimation in Resting Metabolic Rate
Resting metabolic rate (RMR) can also vary and be estimated using prediction equations. Indirect calorimetry is a method used to measure RMR, but even with precise testing, there can be variability in the results. Prediction equations, which are used to estimate RMR based on factors like body mass, age, and height, can also have discrepancies. Individual factors such as weight loss and energy deficits can further impact RMR, leading to lower estimated values compared to prediction equations.
The Future of Body Composition and Metabolic Rate Testing
The future of body composition testing lies in advancements such as 3D scanning from bone-based technologies and select home bioimpedance devices. These methods aim to improve accuracy and reduce biological variability. However, it's important to remember that body composition and RMR testing will always have some level of estimation and variability. Other factors like non-exercise activity thermogenesis can also impact total daily energy expenditure. Therefore, a comprehensive approach that includes multiple measurements and assessments is crucial to understand an individual's unique body composition and metabolic rate.
The duo’s recent pilgrimage to Texas ended with a trip to the state-of-the-art Texas Tech University body composition lab led by Dr. Grant Tinsley. Eric and Omar went through a battery of body composition assessments and had their RMR tested there, and Eric’s second epic duel with the Bod Pod went down. This duel resulted in only partial redemption for Eric, and we also learned just how “headstrong” Omar truly is. In this episode Grant joins Iron Culture to discuss the findings of the trip and all the nuances of body composition testing to help us understand the sometimes non-intuitive results the team got, and more broadly the pros, cons, strengths and weaknesses of the various body composition tests that are available.
00:00 The controversy that the Iron Culture won’t stand for
08:03 Welcoming back on the podcast, Dr Grant Tinsley
13:27 Understanding how body composition is estimated by multiple compartment methods
31:20 The applications of bioelectrical impedance for physique sport peaking
37:00 All about DEXA and how it fits into the six-compartment model
57:24 Explaining errors within body composition assessment
1:08:23 How measurements can be affected and the future of body composition testing
1:19:15 How metabolism is measured and metabolic adaptation
1:30:55 Thanking Dr Grant Tinsley and closing out (The BodPod)