Background The prevalence of overweight and obesity in Norway is increasing both in youth and adults. These patients are at risk of developing chronic diseases, have a reduced quality of life and a reduced life expectancy. The results of conservative treatment of patients with overweight or obesity are not satisfactory. In Norway bariatric surgery is an established and accepted treatment for overweight with comorbidities and obesity in public and private health care. Should patients with overweight with comorbidity and obesity be offered bariatric surgery? Method This article is based on a literature search in electronic databases including both Norwegian and English sources. This paper will describe national and global overweight and obesity. The issue is to describe bariatric surgery including its indications, different procedures, the results and complications. Results The degree for weight loss depends on the specific procedure with a mean excess weight loss of 62% after gastric bypass and 70% after duodenal switch. The common overweight related diseases such as type 2-diabetes, hypertension, hypercholesterolemia, obstructive sleep apnea and metabolic syndrome often improve or go in remission after bariatric surgery. Surgical complications occur in about 20% and the surgical mortality is 1%. The most common complications are weight gain, leakage, gastrointestinal bleeding, internal herniation, anastomotic stricture and ulcus. Vitamin and mineral deficiency and gastrointestinal side effects occur in the majority of patients. Conclusion Bariatric surgery is a very effective treatment of overweight and obesity where patients achieve a better health through weight loss, a reduction or elimination of comorbidity, better quality of life and increased life expectancy. The mortality rate is low, but many experience complications. Observations show that the majority of the patients gain weight with time. There is a need for controlled trails with longer observation time because at this point there are few with longer follow-up than ten years.