A quantitative method for evaluating weight loss using the body mass index (BMI) standard 25, during part or the entire weight loss continuum, was designed and tested.
Weight Loss Index (WLI) represents the area under the curve of the graphical representation of the weight loss attempt; x-axis=time, y-axis=BMI, BMI standard=25.0.
Reliability of the WLI for 1-5 years of weight loss efforts in 50 overweight (BMI=39.1+/-7.6) patients was evaluated by comparing their calculated WLI to a weight loss ratio, derived using a traditional 2-point comparison. Weight Loss Index sensitivity was tested by sending weight loss scenarios to obesity experts, who were asked to rank success of each weight loss attempt within a scenario. Expert rankings were compared to WLI rankings.
Age, weight, height, BMI, WLI.
Dependent t-test for WLI versus pre-post BMI values. Spearman's correlation coefficients for WLI versus expert rankings. Significance, P<.05.
Weight Loss Index better described weight loss attempts for overweight adults than did traditional 2-point comparisons. Obesity experts could not distinguish differences in weight loss success among patients with fluctuating weights, but the WLI categorically ranked these individuals.
CONCLUSIONS AND IMPLICATIONS
Using the WLI, researchers and clinicians can compare the weight loss attempts within an individual, among individuals, and among groups of individuals against the standard BMI reference of 25.0.
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