Aim: Bariatric surgery is the most effective treatment for obesity. However, less than 1% of eligible patients undergo bariatric surgery annually. Here we evaluated the weight loss effectiveness of an intensive non-surgical weight loss program in patients that would qualify for bariatric surgery.

Methods: Patients eligible for bariatric surgery (n = 1460) (BMI≥40 or BMI≥35 kg/m² plus comorbidities) who were enrolled in a dietary weight loss intervention, the RNPC® program, were compared to a cohort of bariatric surgery patients in terms of weight loss outcome.

Results: The 663 patients completing the RNPC® program (35% dropout and 20% ongoing) lost 20.2 ± 11.8 kg corresponding to a reduction of 47% of the excess weight and a percentage weight loss from the initial weight of 18% after a mean period of 18.6 ± 9.1 months. Weight loss 18 months after bariatric surgery (n = 61) was 42.5 ± 15.8 kg corresponding to a reduction of 74% of excess weight and a percentage weight loss from the initial weight of 32%.

Conclusion: Although bariatric surgery results in a more pronounced weight loss, a clinically important weight loss can be obtained in patients that would qualify for bariatric surgery following an intensive non-surgical weight loss program. This retrospective analysis calls for randomized trials that compare the long-term cost-effectiveness between the RNPC® program and bariatric surgery.