A small Australian clinical study showed that sexual function improved significantly and quickly in obese men with type 2 diabetes after weight loss with reduced-calorie diets. For 31 men who lost five percent to ten percent of their body weight in eight weeks, erectile function, sexual desire, and urinary symptoms all improved significantly. According to an article published in the Journal of Sexual Medicine, metabolic parameters, including blood glucose, insulin sensitivity, and lipid profile, also responded favorably to either a low-calorie, meal-replacement diet or a high protein-low carbohydrate diet.
The improvements were maintained during a year of follow-up. Joan Khoo, MRCP, of Changi General Hospital in Singapore, and Australian co-authors wrote, “Further improvements during weight maintenance, using a high-protein low-fat diet, suggest that both nutrient quality and caloric restriction contribute to these benefits.” Although the favorable effect of weight loss on sexual function is not new, this study may be the first to demonstrate an impact on sexual desire.
Another important finding was weight loss’ apparently favorable effect on systemic inflammation. Obesity and type 2 diabetes increase the risk of erectile dysfunction and lower urinary tract symptoms (LUTS), which are associated with each other and with systemic inflammation and endothelial dysfunction.
Rapid weight loss through dieting can improve erectile dysfunction and LUTS. Previous studies also have shown improved endothelial function and reduced inflammation after weight loss, especially for people who lose at least 10 percent of body weight. Not much data had been collected regarding the influence of macronutrient composition on associations between weight loss, endothelial function, systemic inflammation, sexual function, and LUTS in obese men.
All 31 men involved in the study had type 2 diabetes, a body mass index greater than 30, and a waist circumference of at least 102cm. They were randomized to two dietary plans. The first plan was a liquid meal-replacement consumed twice daily and one small, nutritionally balanced meal, providing a total energy of about 900 kcal/day (low-calorie diet). The second plan was a low-fat, low-carbohydrate diet designed to reduce energy intake by about 600 kcal/day.
The first assessment occurred after eight weeks, and follow-up continued for an additional 44 weeks. The participants who opted to stay in the study for long-term follow-up consumed the high-protein diet during the follow-up.
Men in the low-calorie diet group had about ten percent reduction in mean body weight and waist circumference at eight weeks, as compared with about five percent among men assigned to the high-protein diet. Weight loss at eight weeks averaged 9.5kg with the low-calorie diet and 5.4 kg with the high-protein diet, both of which were statistically significant.
In general, inflammatory markers decreased significantly in the high-protein group but not the low-calorie group, but the men assigned to the high-protein diet had higher baseline levels of the markers. About half of the men remained in the study for the entire 52 weeks. Of those who did, improvements were either maintained or increased.