Optimizing Body Composition Measures

Obesity is associated with many chronic diseases, such as cardiovascular disease, diabetes, cancer, neurocognitive decline, and arthritis. Properly prescribed exercise / physical activity and diet are known to have profound effects on preventing obesity and the associated chronic diseases. The Department of EXSS is committed to identifying solutions for this important issue that directly impact’s our society’s quality of life. In addition, we strive to educate future fitness, allied health, and medical professionals on the science of physical activity/exercise prescription, nutrition and behavior modification for preventing and managing chronic disease and injury. In this week’s EXSS Impact post, Dr. Abbie Smith-Ryan provides an overview of her research investigating methods to optimize the tracking of weight loss and body composition over time.

Smith-Ryan AE, Fultz SN, Melvin MN, Wingfield HL, Woessner MN. Reproducibility and Validity of A-Mode Ultrasound for Body Composition Measurement and Classification in Overweight and Obese Men and Women. PLoS One. 2014 Mar 11;9(3):e91750. doi: 10.1371/journal.pone.0091750. eCollection 2014.

Why did you do this study?

Obesity-related health complications have received increased federal attention due to the rising occurrence and associated medical costs. The National Health and Nutrition Examination Survey (NHANES) indicates that approximately 68% of US adults are overweight or obese, with 35.7% of those being classified as obese. The obesity epidemic has given rise to the need for accurate field-based measures of body composition at an individual level in order to better assess a patient’s health risks. An appropriate classification of body composition, specifically fat distribution, may allow for an improved evaluation of an individual’s overall health status. Additionally, clinical settings, such as doctors’ offices and weight loss facilities, may benefit from utilizing accurate field based measurements of percent body fat (%BF) in order to track weight changes over time, and to more effectively identify health risks.

Alterations in body composition typically coincide with changes in metabolism and insulin sensitivity, both positively and negatively. More specifically, adipose tissue has been hypothesized to be a key factor in modulation of lipid and glucose homeostasis. Accurately assessing baseline tissue composition, as well as having the capability of detecting changes in composition, is important in detecting risk and progression of metabolic disease. This methodology is also an important consideration when prescribing and evaluating exercise and diet influences on health.   Regional measures of subcutaneous fat, such as skinfold thickness, are also frequently used as a measure of site-specific and total body composition in field-based assessments. However, the manual measurement of skinfold thickness using anthropometric calipers is somewhat limited, especially in an overweight and obese population. Ultrasound technology has been used for measurement of tissue thickness for decades; however, the technology is not widely utilized for body composition. The A-mode US device used in the current study is a portable, inexpensive field-based device, equipped with body composition software to measure fat mass (FM), fat free mass (FFM), and %BF. Therefore, the purpose of this study was to assess the validity and reliability of a portable A-mode ultrasound for the measurement of body composition in overweight and obese patients.

What did you do and what did you find in this study?

abbie_blogUltrasound measurements were made for body composition, at traditional 7 skinfold sites in forty-seven overweight and obese men. These values were compared to a more sophisticated criterion method for body composition assessments. Patients were further categorized as overweight or obese using body mass index (BMI) or %fat from the US. The results demonstrated that the US more accurately identified overweight and obese individuals, in comparison to the widely used BMI. The portable US was also identified as an accurate tool to track changes in body composition (%fat, fat mass, lean mass).

How do these findings impact the public?

Due to the advantages of the US: affordability, portability and ease of use, it may be beneficial to use in a clinical setting, such as physician clinics, weight loss facilities or gyms, in order to obtain a better assessment of body composition than BMI or skinfolds. Future research should evaluate the feasibility of body composition assessments in various clinics in order to see the impact actual %fat measurement has on earlier diagnoses and prevention of metabolic-related disease progression.

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