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Weight loss and erectile function

Randomised trial

Is fat sexy? Perhaps it depends on one's perspective, but there is certainly good evidence that in overweight men there are high reported levels of erectile dysfunction, and that risk of erectile dysfunction increases with increasing BMI. The implication is that losing weight would restore or improve erectile function, and a randomised trial [1] shows that to be the case.

Randomised trial

This Italian study enrolled young men between 35 and 55 years from a weight loss clinic in Naples. For inclusion they had to have an International Index of Erectile Function (IIEF) score of 21 points or less out of the maximum of 25. The IIEF was described in Bandolier 90, and has five questions on erectile function, each scored on a scale of 1 to 5. Scores of 21 or below are indicative of erectile dysfunction. Use of drugs for erectile function was an exclusion criterion.

Men were randomly assigned to detailed advice about how to achieve a body weight reduction of 10% or more, with instruction about caloric intake, setting goals, and self-monitoring, with monthly small group sessions. Behavioural and psychological counselling was also available. The goal was a diet containing 1700 kcal daily for the first year, and 1900 daily for the second, and with targets for carbohydrates, protein, unsaturated fats, and fibre. Men in the control group were given general oral and written information about healthy food choice and exercise at every visit, but without specific individualised programmes.

Detailed measurements were made at various times over two years, to include blood tests, food diaries, and erectile function.


The intervention and control groups (55 men in each) were similar at baseline, with an average age of 43 years, weight of 102 kg, and BMI of 36. At two years the control group had virtually no change in caloric intake, while men in the intervention group had an average of 340 kcal less every day, and also took much more daily exercise. Men in the intervention group increased their intake of fibre, protein, and unsaturated fat, and decreased their consumption of saturated fat and cholesterol.

The result was that in the intervention group men lost an average of 15 kg, their BMI fell to 31, and they developed a waist. In the control group there was no change in average weight or in IIEF score, while in the intervention group weight loss and improvement in IIEF score were proportionate (Figure 1).

Figure 1: Change in average weight and IIEF scores over two years in men on intensive weight loss programme or control

By the end of two years, three of 55 men (5%) in the control group who originally had IIEF scores of 21 or less now had scores of 22 or greater. In the intervention group, 17 men (31%) now had scores of 22 or greater, indicating that they did not have erectile dysfunction. The number needed to treat for weight loss to restore erectile function was 3.9 (95% CI 2.6 to 8.4)

There were also significant improvements in blood pressure (by about 3 mmHg on average), total and high density cholesterol, triglycerides, fasting glucose, C-reactive protein and other variables in men in the intervention group following weight loss.


Observational studies linking overweight to erectile dysfunction in men create a hypothesis that losing weight could restore erectile function. The randomised trial may be small in numbers, but was impeccable in detail, and had a very positive result. The NNT of 4 was an intention-to-treat value based on all men randomised, despite about six withdrawing, three in each group.

The intensive behavioural intervention produced big weight reductions, and a significant minority of men had restored erectile function. Their average weight was still 88 kg after two years, and BMI was 31 after two years, so even more men may have benefited with continuing weight loss.

Thinner meant more sex, or opportunity for it, in these young men, as well as overall better health. Bandolier 133 demonstrated how significant weight loss led to less knee arthritis in an older population. These are important lessons about how overweight is bad, and proper weight is good. A clear message is developing that for those people who are overweight, structured weight loss can restore better health.


  1. K Eposito et al. Effect of lifestyle changes on erectile dysfunction in obese men. A randomized controlled trial. JAMA 2004 291: 2978-2984.

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