To investigate the effects of various diets on structure and function of the bladder in both normal and obstructed bladders of male Wistar rats.Sham-operated rats and rats with experimentally-induced bladder outlet obstruction (BOO) were fed with standard rats' feed (control), High-carbohydrate (HCD), High-fat (HFD) and High-protein (HPD) diets. Feeding was continued for 4 weeks after BOO surgery. Bladder weight, detrusor contractility, Rho-Kinase (ROK) and Myosin Light Chain Kinase (MLCK) expressions were determined using standard methods.In comparison with control, bladder weight was increased in HFD (164 ± 9 mg), BOO (437 ± 21 mg), HFD-BOO (523 ± 19 mg) and HPD-BOO (268 ± 18 mg). Detrusor contractility was reduced in BOO and HFD-BOO. The ROK- I and II expressions were high in HCD-BOO and low in HPD-BOO but ROK-I was also elevated in BOO. However, MLCK increased only in HCD-BOO.The results of the study reveal that diets with varying macronutrient compositions have variable effects on the bladder with and without obstruction. High-fat diets especially, affect detrusor morphology and function in both obstructed and unobstructed bladders.