title: Assessment of maximum weight change and duration of therapeutic effect for non-surgical treatment of obesity using an exponential model.
abstract: Efficacy of weight loss and maintenance therapies in obesity is difficult to quantify due to continuous weight changes over time. We assessed a single exponential model of weight changes during selected non-surgical therapies of non-diabetic obese subjects. We analyzed published mean weight data from 6 studies of ≥12 weeks duration, with comparable treatment groups, and ≥4 weight measurements during very low carbohydrate or fat diets, or treatment with Lorcaserin, Sibutramine or Orlistat. We fit data to a single exponential model to estimate maximum predicted weight loss or regain and duration of weight loss or regain for each therapy. A single exponential is the appropriate model as determined by Kolmogorov-Smirnov, constant variance, and Durbin-Watson tests. Validity of parameter estimates was indicated by coefficients of variation <25%. Sensitivity analysis showed that weight regain at the end of the weight loss phase affected parameter estimates in some instances, with variations of weight loss of 0.2-0.7% of basal. Estimated weight loss and regain were similar to observed weight changes in all studies. The model could also be used to assess dose-response relationships. Estimates from the model were used to compare concurrent obesity regimens using 95% confidence intervals, taking into account pre-determined minimal clinically important differences. This exponential model may provide accurate estimates of maximum achievable weight loss or regain and optimal duration of efficacy for a variety of non-surgical weight loss and maintenance regimens from published mean weight data and may be useful to more accurately evaluate weight loss and maintenance regimens.
authors.affiliation: Department of Medicine, University of Southern California, Los Angeles, CA 90033, USA. ekaptein@usc.edu
authors.forename: E M
authors.initials: EM
authors.lastname: Kaptein
authors.forename: L S
authors.initials: LS
authors.lastname: Chan
authors.forename: J S
authors.initials: JS
authors.lastname: Kaptein
mesh_terms: D000328:Adult; D019440:Anti-Obesity Agents / Q000627:therapeutic use*; D001067:Appetite Depressants / Q000627:therapeutic use; D001552:Benzazepines / Q000627:therapeutic use; D015992:Body Mass Index; D001835:Body Weight; D003503:Cyclobutanes / Q000627:therapeutic use; D004035:Diet Therapy / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007783:Lactones / Q000627:therapeutic use; D008297:Male; D008962:Models, Theoretical; D009765:Obesity / Q000178:diet therapy / Q000188:drug therapy / Q000503:physiopathology; D000077403:Orlistat; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D015431:Weight Loss / Q000187:drug effects
chemical_list: D019440:Anti-Obesity Agents; D001067:Appetite Depressants; D001552:Benzazepines; D003503:Cyclobutanes; D007783:Lactones; C506658:lorcaserin; D000077403:Orlistat; C058254:sibutramine