title: Relatively high-protein or 'low-carb' energy-restricted diets for body weight loss and body weight maintenance?
abstract: BACKGROUND
  'Low-carb' diets have been suggested to be effective in body weight (BW) management. However, these diets are relatively high in protein as well.
  
  
  OBJECTIVE
  To unravel whether body-weight loss and weight-maintenance depends on the high-protein or the 'low-carb' component of the diet.
  
  
  METHODS
  Body-weight (BW), fat mass (FM), blood- and urine-parameters of 132 participants (age=50 ± 12 yr; BW=107 ± 20 kg; BMI=37 ± 6 kg/m(2); FM=47.5 ± 11.9 kg) were compared after 3 and 12 months between four energy-restricted diets with 33% of energy requirement for the first 3 months, and 67% for the last 9 months: normal-protein normal-carbohydrate (NPNC), normal-protein low-carbohydrate (NPLC); high-protein normal-carbohydrate (HPNC), high-protein low-carbohydrate (HPLC); 24h N-analyses confirmed daily protein intakes for the normal-protein diets of 0.7 ± 0.1 and for the high-protein diets of 1.1 ± 0.2g/kg BW (p<0.01).
  
  
  RESULTS
  BW and FM decreased over 3 months (p<0.001): HP (-14.1 ± 4 kg; -11.9 ± 1.7 kg) vs. NP (-11.5 ± 4 kg; -9.3 ± 0.7 kg) (p<0.001); LC (-13.5 ± 4 kg; -11.0 ± 1.2 kg) vs. NC (-12.3 ± 3 kg; -10.3 ± 1.1 kg) (ns). Diet × time interaction showed HPLC (-14.7 ± 5 kg; -11.9 ± 1.6 kg) vs. HPNC (-13.8 ± 3 kg; -11.9 ± 1.8 kg) (ns); NPLC (-12.2 ± 4 kg; -10.0 ± 0.8 kg) vs. NPNC (-10.7 ± 4 kg; -8.6 ± 0.7 kg) (ns); HPLC vs. NPLC (p<0.001); HPNC vs. NPNC (p<0.001). Decreases over 12 months (p<0.001) showed HP (-12.8 ± 4 kg; -9.1 ± 0.8 kg) vs. NP (-8.9 ± 3 kg; -7.7 ± 0.6 kg) (p<0.001); LC (-10.6 ± 4 kg; -8.3 ± 0.7 kg) vs. NC (11.1 ± 3 kg; 9.3 ± 0.7 kg) (ns). Diet × time interaction showed HPLC (-11.6 ± 5 kg ; -8.2 ± 0.7 kg) vs. HPNC (-14.1 ± 4 kg; -10.0 ± 0.9 kg) (ns); NPNC (-8.2 ± 3 kg; -6.7 ± 0.6 kg) vs. NPLC (-9.7 ± 3 kg; -8.5 ± 0.7 kg) (ns); HPLC vs. NPLC (p<0.01); HPNC vs. NPNC (p<0.01). HPNC vs. all other diets reduced diastolic blood pressure more. Relationships between changes in BW, FM, FFM or metabolic parameters and energy percentage of fat in the diet were not statistically significant. Metabolic profile and fat-free-mass were improved following weight-loss.
  
  
  CONCLUSIONS
  Body-weight loss and weight-maintenance depends on the high-protein, but not on the 'low-carb' component of the diet, while it is unrelated to the concomitant fat-content of the diet.
authors.affiliation: Department of Human Biology, Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands; Top Institute Food and Nutrition (TIFN), Wageningen, The Netherlands.
authors.forename: Stijn
authors.initials: S
authors.lastname: Soenen
authors.forename: Alberto G
authors.initials: AG
authors.lastname: Bonomi
authors.forename: Sofie G T
authors.initials: SG
authors.lastname: Lemmens
authors.forename: Jolande
authors.initials: J
authors.lastname: Scholte
authors.forename: Myriam A M A
authors.initials: MA
authors.lastname: Thijssen
authors.forename: Frank
authors.initials: F
authors.lastname: van Berkum
authors.forename: Margriet S
authors.initials: MS
authors.lastname: Westerterp-Plantenga
mesh_terms: D000328:Adult; D000368:Aged; D001786:Blood Glucose; D001794:Blood Pressure / Q000502:physiology; D001823:Body Composition / Q000502:physiology; D001835:Body Weight / Q000502:physiology*; D003404:Creatinine / Q000097:blood; D050528:Diet, Carbohydrate-Restricted; D018752:Diet, Fat-Restricted; D004311:Double-Blind Method; D005247:Feeding Behavior / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007118:Immunoassay; D007328:Insulin / Q000097:blood; D008074:Lipoproteins / Q000097:blood; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D011795:Surveys and Questionnaires; D015431:Weight Loss / Q000502:physiology*; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D007328:Insulin; D008074:Lipoproteins; D003404:Creatinine