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Comparing Effects of a Low-energy Diet and a High-protein Low-fat Diet on Sexual and Endothelial Function, Urinary Tract Symptoms, and Inflammation in Obese Diabetic Men


Joan Khoo, MRCP, Department of Endocrinology, Changi General Hospital, Singapore, Singapore 529889. Tel: +65-68503807; Fax: +65-67816202; E-mail:


Introduction.  Abdominal obesity and type 2 diabetes mellitus are associated with sexual and endothelial dysfunction, lower urinary tract symptoms (LUTS), and chronic systemic inflammation.

Aim.  To determine the effects of diet-induced weight loss and maintenance on sexual and endothelial function, LUTS, and inflammatory markers in obese diabetic men.

Main Outcome Measures.  Weight, waist circumference (WC), International Index of Erectile Function (IIEF-5) score, Sexual Desire Inventory (SDI) score, International Prostate Symptom Scale (IPSS) score, plasma fasting glucose and lipids, testosterone, sex hormone binding globulin (SHBG), inflammatory markers (high-sensitivity C-reactive protein [CRP] and interleukin-6 [IL-6]) and soluble E-selectin, and brachial artery flow-mediated dilatation (FMD) were measured at baseline, 8 weeks, and 52 weeks.

Methods.  Over 8 weeks, 31 abdominally obese (body mass index ≥ 30 kg/m2, WC ≥ 102 cm), type 2 diabetic men (mean age 59.7 years) received either a meal replacement-based low-calorie diet (LCD) ∼1,000 kcal/day (N = 19) or low-fat, high-protein, reduced-carbohydrate (HP) diet (N = 12) prescribed to decrease intake by ∼600 kcal/day. Subjects continued on, or were switched to, the HP diet for another 44 weeks.

Results.  At 8 weeks, weight and WC decreased by ∼10% and ∼5% with the LCD and HP diet, respectively. Both diets significantly improved plasma glucose, low-density lipoprotein (LDL), SHBG, IIEF-5, SDI and IPSS scores, and endothelial function (increased FMD, reduced soluble E-selectin). Erectile function, sexual desire, and urinary symptoms improved by a similar degree with both diets. CRP and IL-6 decreased with the HP diet. At 52 weeks, reductions in weight, WC, and CRP were maintained. IIEF-5, SDI, and IPSS scores improved further.

Conclusions.  Diet-induced weight loss induces rapid improvement of sexual, urinary, and endothelial function in obese diabetic men. A high-protein, carbohydrate-reduced, low-fat diet also reduces systemic inflammation and sustains these beneficial effects to 1 year. Khoo J, Piantadosi C, Duncan R, Worthley SG, Jenkins A, Noakes M, Worthley MI, Lange K, and Wittert GA. Comparing effects of a low-energy diet and a high-protein low-fat diet on sexual and endothelial function, urinary tract symptoms and inflammation in obese diabetic men. J Sex Med 2011;8:2868–2875.