title: Effects of a high-protein ketogenic diet on hunger, appetite, and weight loss in obese men feeding ad libitum.
abstract: BACKGROUND
  Altering the macronutrient composition of the diet influences hunger and satiety. Studies have compared high- and low-protein diets, but there are few data on carbohydrate content and ketosis on motivation to eat and ad libitum intake.
  
  
  OBJECTIVE
  We aimed to compare the hunger, appetite, and weight-loss responses to a high-protein, low-carbohydrate [(LC) ketogenic] and those to a high-protein, medium-carbohydrate [(MC) nonketogenic] diet in obese men feeding ad libitum.
  
  
  METHODS
  Seventeen obese men were studied in a residential trial; food was provided daily. Subjects were offered 2 high-protein (30% of energy) ad libitum diets, each for a 4-wk period-an LC (4% carbohydrate) ketogenic diet and an MC (35% carbohydrate) diet-randomized in a crossover design. Body weight was measured daily, and ketosis was monitored by analysis of plasma and urine samples. Hunger was assessed by using a computerized visual analogue system.
  
  
  RESULTS
  Ad libitum energy intakes were lower with the LC diet than with the MC diet [P=0.02; SE of the difference (SED): 0.27] at 7.25 and 7.95 MJ/d, respectively. Over the 4-wk period, hunger was significantly lower (P=0.014; SED: 1.76) and weight loss was significantly greater (P=0.006; SED: 0.62) with the LC diet (6.34 kg) than with the MC diet (4.35 kg). The LC diet induced ketosis with mean 3-hydroxybutyrate concentrations of 1.52 mmol/L in plasma (P=0.036 from baseline; SED: 0.62) and 2.99 mmol/L in urine (P<0.001 from baseline; SED: 0.36).
  
  
  CONCLUSIONS
  In the short term, high-protein, low-carbohydrate ketogenic diets reduce hunger and lower food intake significantly more than do high-protein, medium-carbohydrate nonketogenic diets.
authors.affiliation: Division of Obesity and Metabolic Health and Biomathematics and Statistics Scotland, Rowett Research Institute, Aberdeen, United Kingdom. a.johnstone@rowett.ac.uk
authors.forename: Alexandra M
authors.initials: AM
authors.lastname: Johnstone
authors.forename: Graham W
authors.initials: GW
authors.lastname: Horgan
authors.forename: Sandra D
authors.initials: SD
authors.lastname: Murison
authors.forename: David M
authors.initials: DM
authors.lastname: Bremner
authors.forename: Gerald E
authors.initials: GE
authors.lastname: Lobley
mesh_terms: D000328:Adult; D000368:Aged; D001066:Appetite / Q000187:drug effects / Q000502:physiology*; D001823:Body Composition / Q000187:drug effects / Q000502:physiology; D018592:Cross-Over Studies; D050528:Diet, Carbohydrate-Restricted; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D002149:Energy Intake / Q000187:drug effects / Q000502:physiology; D006801:Humans; D006815:Hunger / Q000187:drug effects / Q000502:physiology*; D007662:Ketosis / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000178:diet therapy*; D012307:Risk Factors; D015431:Weight Loss
chemical_list: D004040:Dietary Carbohydrates; D004044:Dietary Proteins