Title of article:

Weight Loss-Induced Skeletal Muscle Loss: Accurate Estimation by Bioimpedance Analysis (BIA)

Authors: Nuñez C, Kovera A, Wang ZM, Heymsfield SB.
Presented at : 8th International Congress on Obesity, Paris, August 29-September 3. 1998.

Abstract

Objective: Loss of skeletal muscle (SM) is a characteristic body composition change associated with weight reduction treatment. Prevention of dieting-SM atrophy with appropriate food composition or exercise is an important research goal.
Design: This study evaluated the accuracy of BIA (50kHz) in monitoring leg SM changes in a group of 71 obese women (X±SD, age, 40.0±7.3 yrs; BMI, 31.1±2.8kg/m2) undergoing 16-week weight loss treatment on conventional low calorie diet.
Methods: Leg-to-leg impedance, adjusted for stature (Ht2/Z), was measured with contact electrode BIA system at the beginning and end of weight loss. Leg SM prediction model was developed in second group of 135 normal women using dual-energy X-ray absorptiometry as reference for leg SM [leg SM (kg)=0.25x(Ht2/Z)-0.03xAge+3.5; SEE=1.42 kg, r=0.79, p<0.001].
Results: Subjects lost mean of 4.9 kg body mass, 4.3 kg as fat and 0.6 kg as fat-free mass. Pre-weight loss there was a strong correlation between predicted (Pr) and measured (M) leg SM (r=0.86, p<0.001; Pr=15.9±2.3 kg vs M=16.0±3.4 kg; p=NS). Similarly, agreement between Pr and M leg SM was good at post-weight loss (r=0.89, p<0.001; Pr=15.7±2.3 kg vs. M=15.8±3.4 kg; p=NS). There was a significant correlation between predicted and measured change in leg SM (r=0.45, p<0.001) and the mean change in Pr leg SM (-0.20±0.79 kg) was not significantly different from M leg SM (-0.22±0.52 kg).
Conclusion: These results strongly support the use of BIA for leg SM prediction in obese subjects and suggest a role for BIA in monitoring group SM changes in weight loss studies.

Comments and Key points

This study used Tanita equipment to measure bioelectrical impedance, to measure body fat percentages. The formulas for predicting the amount skeletal muscle seem accurate, before and after a weight loss program.

 

References

  1. http://www.tanita.com/professional/abstracts/abstract_main.html

Review & comments by Steven B. Halls, MD, Last edited 26-May-2008 Copyright.

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