title: Long-Term Effects of a Randomised Controlled Trial Comparing High Protein or High Carbohydrate Weight Loss Diets on Testosterone, SHBG, Erectile and Urinary Function in Overweight and Obese Men.
abstract: BACKGROUND
  Obesity is associated with reduced testosterone and worsened erectile and sexual function in men. Weight loss improves these outcomes. High protein diets potentially offer anthropometric and metabolic benefits, but their effects on reproductive and sexual outcomes is not known.
  
  
  OBJECTIVE
  To examine the long-term effects of weight loss with a higher protein or carbohydrate diet on testosterone, sex hormone binding globulin, erectile dysfunction, lower urinary tract symptoms and sexual desire in overweight and obese men.
  
  
  METHODS
  One-hundred and eighteen overweight or obese men (body mass index 27-40 kg/m2, age 20-65 years) were randomly assigned to an energy restricted higher protein low fat (35% protein, 40% carbohydrate, 25% fat; n = 57) or higher carbohydrate low fat diet (17% protein, 58% carbohydrate, 25% fat, n = 61) diet for 52 weeks (12 weeks weight loss, 40 weeks weight maintenance). Primary outcomes were serum total testosterone, sex hormone binding globulin and calculated free testosterone. Secondary outcomes were erectile function as assessed by the International Index of Erectile Function (IIEF) (total score and erectile function domain), lower urinary tract symptoms and sexual desire.
  
  
  RESULTS
  Total testosterone, sex hormone binding globulin and free testosterone increased (P<0.001) and the total IIEF increased (P = 0.017) with no differences between diets (P≥0.244). Increases in testosterone (P = 0.037) and sex hormone binding globulin (P<0.001) and improvements in the total IIEF (P = 0.041) occurred from weeks 0-12 with a further increase in testosterone from week 12-52 (P = 0.002). Increases in free testosterone occurred from week 12-52 (p = 0.002). The IIEF erectile functon domain, lower urinary tract symptoms and sexual desire did not change in either group (P≥0.126).
  
  
  CONCLUSIONS
  In overweight and obese men, weight loss with both high protein and carbohydrate diets improve testosterone, sex hormone binding globulin and overall sexual function.
  
  
  BACKGROUND
  Anzctr.org.au ACTRN12606000002583.
authors: The Robinson Research Institute, Discipline of Obstetrics and Gynaecology, University of Adelaide, Adelaide, South Australia, Australia.
authors: Lisa J
authors: LJ
authors: Moran
authors: CSIRO Food and Nutrition, Adelaide, South Australia, Australia.
authors: Grant D
authors: GD
authors: Brinkworth
authors: Freemasons Foundation Centre for Mens Health, University of Adelaide, and South Australian Institute for Health and Medical Research, Adelaide, South Australia, Australia.
authors: Sean
authors: S
authors: Martin
authors: Division of Health Sciences, University of South Australia, Adelaide, South Australia, Australia.
authors: Thomas P
authors: TP
authors: Wycherley
authors: Keogh Institute for Medical Research, University of Western Australia, Perth, Western Australia, Australia.
authors: Bronwyn
authors: B
authors: Stuckey
authors: CSIRO Food and Nutrition, Adelaide, South Australia, Australia.
authors: Janna
authors: J
authors: Lutze
authors: Division of Health Sciences, University of South Australia, Adelaide, South Australia, Australia.
authors: Peter M
authors: PM
authors: Clifton
authors: Freemasons Foundation Centre for Mens Health, University of Adelaide, and South Australian Institute for Health and Medical Research, Adelaide, South Australia, Australia.
authors: Gary A
authors: GA
authors: Wittert
authors: CSIRO Food and Nutrition, Adelaide, South Australia, Australia.
authors: Manny
authors: M
authors: Noakes
mesh_terms: D000328:Adult; D000368:Aged; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004044:Dietary Proteins / Q000008:administration & dosage*; D007172:Erectile Dysfunction / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood* / Q000150:complications / Q000503:physiopathology; D050177:Overweight / Q000097:blood* / Q000150:complications / Q000503:physiopathology; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism*; D013739:Testosterone / Q000097:blood*; D014554:Urination; D015431:Weight Loss; D055815:Young Adult
chemical_list: D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D012738:Sex Hormone-Binding Globulin; D013739:Testosterone