This is the first lifestyle modification study that reported an improvement in ED, MeTS components, and PASI after a 12-week randomized-controlled program of exercise and diet restriction in men with CPP, ED, and MeTS.

The exercise-induced decrease in psoriatic severity may be in part due to a decrease in obesity-associated high mass of adipose tissue. Decreased mass of adipose tissue is associated with a decreased release of inflammatory cytokines involved in the pathogenesis of psoriasis. Decreased production of cytokines not only restricts the causative role in the induction of CPP [15], but also improves the low-grade systemic inflammation [16] which is the common factor in the occurrence of CPP-associated comorbidities such as cardiovascular diseases (CVD), MeTS [15], and ED [9].

The suggested mechanisms that explain the improvement in MeTS components in this CPP study reduction may be reported as follows: reduction in overactivity of the sympathetic nervous system; improvement in elastic and endothelial properties/functions of vessels; enhancement functions of micro- and macrocirculation; increased production of vasodilating substances such as nitric oxide (NO), reduced production of plasma vasoconstrictors/catecholamines [17]; improved insulin resistance (may be due to repeated contraction of large muscles of lower limbs that increase the transportation, phosphorylation, and oxidization of glucose molecules during walking) [5]; and increased activity of lipolytic enzymes that catabolize STG [18, 19].

Supporting us, treatment with a low-calorie diet (a reduced food intake reaching 800–1000 kcal/day for 2 months followed by a reduced food intake reaching 1200 kcal/day for 2 months) in overweight/obese patients with CPP showed a trend in favor of clinically important improvements in BMI, WC, SFBG, PASI [16], STG, cholesterol, diastolic BP, glycated hemoglobin, and tissue plasminogen activator inhibitor [20]. Also, the median improvement in PASI of obese and overweight patients with psoriasis who followed a protocol of a 20-week low-calorie diet and exercise was greater than patients who did not follow the same protocol [21]. In overweight/obese patients with CPP, the aggressive first-line weight-loss program (very-low-calorie ketogenic diet followed by Mediterranean diet) that was followed by the patients for 10 weeks without prescribing psoriatic medications produced a significant reduction in PASI [22].

The 24-week low-calorie diet produced significant changes in BMI, WC, STG, and SHDL, but SFBG did not show significant changes despite the decrease in its level due to the small number (n = 10) of obese patients with CPP [23].

In obese patients with CPP, despite non-significant improvements in SHDL and STG, PASI improvement could be increased by adding diet restriction protocols, mainly the low-calorie diet, to the course of pharmacological therapies [24]. In obese patients with CPP, despite non-significant improvements in STG, besides the significant decrease in patients’ weight and WC, adding an 8-week low-calorie diet (≤ 1000 kcal/day) to biological therapies (infliximab, etanercept, adalimumab, and ustekinumab) achieved greater improvement in PASI than biological therapies alone [25].

Regarding ED improvement, adherence to weight-loss programs including diet restriction and/or increased physical activity augments a strong penile erection in ED sufferers, likely via improving mood and self-esteem, increasing serum testosterone levels [26], regulating the disturbances of metabolic profile (proinflammatory markers, insulin resistance, and dyslipidemia), decreasing the mass of visceral adipose tissue, improving vascular functions (improving endothelial dysfunction, increased NO production, and increased local blood supply to the penis) [27], increasing relaxation of smooth muscular tissues of the penis, and inducing neuro-biochemical/hormonal changes involved in the process of penile erection [12].

Esposito et al. [28] supported our results because their results were compatible with our results, especially after their random assignment of 110 ED men to an intervention group (n = 55 obese men, the role of the authors in this group was to guide men how to lose 10% of their weight over one year through a detailed prescription of restricting diet calories and how to increase exercise levels) or control group (n = 55 obese men, the role of the authors in this group was to guide men how to lose 10% of their weight over one year through a piece of general non-detailed information about diet restriction or increasing the daily exercise levels). Esposito et al. [28] showed that the intervention group produced higher significant improvement in the tested outcomes (weight, BMI, SHDL, STG, blood pressure, IIEFQ-5, and glucose) than the control group.

Esposito et al. [29] supported our results because their results were compatible with our results, especially after their random assignment of 209 obese men to a 104-men intervention group (34% of men had IIEFQ-5 > 21, the role of the authors in this group was to guide men to how to lose their weight over two years through a detailed prescription on how to restrict calories of diet and how to increase exercise levels) or 105-men control group (36% of men had IIEFQ-5 > 21, the role of the authors in this group was to guide men to lose their weight over two years through a piece of general non-detailed information about diet restriction or increasing the daily exercise levels). Besides the trend of improvement in weight, BMI, SHDL, STG, blood pressure, and blood glucose in favor of the intervention group, after ending the 2-year period, Esposito et al. [29] showed that the percentage of men in the intervention group who had normal IIEFQ-5 > 21 increased to 56% while the percentage of men in the control group who had normal IIEFQ-5 > 21 increased to 38%.

The response of IIEFQ-5 to an 8-week interval exercise in hypertensive men with ED was compatible with our results because IIEFQ-5 significantly increased after the interval exercise program [30]. Again, besides the significant improvement in BMI, insulin resistance, WC, BP, SHDL, and STG, an 8-week elliptical exercise increased the efficacy of ED pharmacotherapies in obese men with mild and moderate ED [12].

Except for WC and diastolic BP, comparing the post results of obese men with ED who followed a Mediterranean diet protocol with the post results of obese men with ED who did not follow any calorie restriction diet showed significant improvements in systolic BP, SHDL, STG, blood glucose, and IIEFQ-5 in favor of Mediterranean diet men [31].

The results of the random assignment of overweight and obese diabetic men with ED to a group of an intensive lifestyle-modification program (diet restriction with exercise) or a group of diabetes education/support program were compatible with our results due to the trend of improvement in tested outcomes (weight, glycosylated hemoglobin, BP, IIEFQ-5, and SHDL) was in favor of the group of the intensive lifestyle modification program [32].

Opposite to us, despite augmenting the high efficacy of ED pharmacotherapies in the treatment of ED in MeTS men with ED, adding exercise to ED pharmacotherapies did not augment significant improvements in BP, WC, SHDL, STG, and blood glucose due to including a small number (n = 10) of MeTS elderly with ED [33].