We first want to thank the group of Dr. Scheimann for their remarks. We agree with them when they insist on the fact that surgery on Prader–Willi patients (PWP) is much more difficult and dangerous than on non-PWP and requires greater expertise. We feel our article did not insist enough on this aspect. However, we disagree with this group and continue to sustain that despite its greater difficulty, bariatric surgery is very much justified in these patients when morbid obesity is present.

We attribute the difference of opinion on their lack of experience with bariatric surgery. Their attitude resemble that of medical specialists in the treatment of adults severe obesity, who for 20 years have been reluctant to recognize the benefits of surgery arguing that conservative measures (diet, exercise, behaviour support) were more efficient. It took years before they changed their mind. Without denying the essential role of conservative measures for preventing morbid obesity, it is obvious that once morbid obesity is present, surgery is not only justified but probably the best treatment.

Our referred article concerned only three patients with PWS because it was limited to adolescents (<18 years), but our total experience includes seven patients aged 5–21 years old. They have lost a mean of 38 kg (nadir weight), and after 7.5 years (2–12) of follow-up, they are still 25 kg below their initial weight and still eating normally. Clearly these benefits outweigh the operative risk which will decrease with time.

The loss of more than 30 kg while enjoying normal eating habits without severe restriction provides an improved quality of life for both children and parents. The cure of diabetes and sleep apnea are also valuable benefits. These improvements are important even if they might not last forever and despite the need for continuous patient care and support.

In regard to bariatric surgery, we believe paediatricians will follow the same evolution as did the endocrinologists: with accumulation of data, they will change their opinion. I am sure the co-authors of our article share my point of view.

Picard Marceau