title: A method to achieve control of dietary macronutrient composition in ad libitum diets consumed by free-living subjects.
abstract: OBJECTIVE
  To validate a shop system in controlling macronutrient composition during ad libitum dietary intervention.
  
  
  METHODS
  Six months randomized intervention trial.
  
  
  METHODS
  A shop at the department from which all foods were collected free of charge and registered by a purpose-designed computer system.
  
  
  METHODS
  Sixty-five free-living obese subjects (25 kg/m2 < BMI < 34 kg/m2) recruited through advertisement and from a waiting list at the Department. Total drop-out rate was 8%.
  
  
  METHODS
  Ad libitum low-fat diets (30 energy-% (E%) fat): (1) High-protein (25 E% protein, HP) or (2) Low-protein, (12 E% protein, LP) or habitual diet (controls, C).
  
  
  METHODS
  Compliance was assessed by 24 h urinary nitrogen excretion (24 h UN).
  
  
  RESULTS
  After one month of dietary intervention 24 h UN increased significantly in the HP group and decreased significantly in the LP group (Group difference 95% CI):6.8 g (5.0-8.7 g), P < 0.0001). This group difference remained throughout the trial. There was good agreement between protein intake as estimated by the shop computer and as estimated from 24 h UN in both first (r = 0.86) and second half of the intervention (r = 0.80).
  
  
  CONCLUSIONS
  The high dietary compliance demonstrates the potential of this method to control macronutrient composition in ad libitum dietary intervention studies in free-living subjects.
authors.affiliation: Research Department of Human Nutrition, Royal Verterinary and Agricultural University, Frederiksberg, Copenhagen, Denmark.
authors.forename: A R
authors.initials: AR
authors.lastname: Skov
authors.forename: S
authors.initials: S
authors.lastname: Toubro
authors.forename: A
authors.initials: A
authors.lastname: Raben
authors.forename: A
authors.initials: A
authors.lastname: Astrup
mesh_terms: D000293:Adolescent; D000328:Adult; D004032:Diet; D004041:Dietary Fats / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009584:Nitrogen / Q000097:blood; D009765:Obesity / Q000178:diet therapy*; D010349:Patient Compliance
chemical_list: D004041:Dietary Fats; D004044:Dietary Proteins; D009584:Nitrogen