title: Weight loss on low-fat vs. low-carbohydrate diets by insulin resistance status among overweight adults and adults with obesity: A randomized pilot trial.
abstract: OBJECTIVE
  To test for differential weight loss response to low-fat (LF) vs. low-carbohydrate (LC) diets by insulin resistance status with emphasis on overall quality of both diets.
  
  
  METHODS
  Sixty-one adults, BMI 28-40 kg/m(2) , were randomized in a 2 × 2 design to LF or LC by insulin resistance status in this pilot study. Primary outcome was 6-month weight change. Participants were characterized as more insulin resistant (IR) or more insulin sensitive (IS) by median split of baseline insulin-area-under-the-curve from an oral glucose tolerance test. Intervention consisted of 14 one-hour class-based educational sessions.
  
  
  RESULTS
  Baseline % carbohydrate:% fat:% protein was 44:38:18. At 6 months, the LF group reported 57:21:22 and the LC group reported 22:53:25 (IR and IS combined). Six-month weight loss (kg) was 7.4 ± 6.0 (LF-IR), 10.4 ± 7.8 (LF-IS), 9.6 ± 6.6 (LC-IR), and 8.6 ± 5.6 (LC-IS). No significant main effects were detected for weight loss by diet group or IR status; there was no significant diet × IR interaction. Significant differences in several secondary outcomes were observed.
  
  
  CONCLUSIONS
  Substantial weight loss was achieved overall, but a significant diet × IR status interaction was not observed. Opportunity to detect differential response may have been limited by the focus on high diet quality for both diet groups and sample size.
authors.affiliation: Stanford Prevention Research Center, Department of Medicine, Stanford University Medical School, Stanford, California, USA.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Gardner
authors.affiliation: Stanford Prevention Research Center, Department of Medicine, Stanford University Medical School, Stanford, California, USA.
authors.forename: Lisa C
authors.initials: LC
authors.lastname: Offringa
authors.affiliation: Stanford Prevention Research Center, Department of Medicine, Stanford University Medical School, Stanford, California, USA.
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Hartle
authors.affiliation: Quantitative Sciences Unit, Department of Medicine, Stanford University Medical School, Stanford, CA.
authors.forename: Kris
authors.initials: K
authors.lastname: Kapphahn
authors.affiliation: Stanford Prevention Research Center, Department of Medicine, Stanford University Medical School, Stanford, California, USA.
authors.forename: Rise
authors.initials: R
authors.lastname: Cherin
mesh_terms: D000328:Adult; D050528:Diet, Carbohydrate-Restricted; D018752:Diet, Fat-Restricted; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000178:diet therapy* / Q000378:metabolism; D050177:Overweight / Q000178:diet therapy* / Q000378:metabolism / Q000382:microbiology; D010865:Pilot Projects; D015431:Weight Loss
chemical_list: D007328:Insulin