Weight loss diets before elective surgery do not reduce postoperative complications

A new systematic review by researchers in Sydney, Australia, published in the journal Clinical Obesity, suggests that weight loss diets before elective surgery are ineffective in reducing postoperative complications.

Pavlovic and colleagues analysed a selection of studies that compared effects of low-calorie diets using meal replacement formulas to standard care on postoperative outcomes in adults with obesity awaiting surgery. They found “very low-quality evidence of a statistically significant difference favouring the intervention for preoperative weight loss”, as well as some evidence that “preoperative weight-loss diets do not reduce postoperative complications to 30 days.” Whilst acknowledging that existing data are limited and tend to be of low-quality, the authors concluded that weight-loss diets do not appear to reduce postoperative complications based on the evidence available.

The study could have significant implications for the policies of health services worldwide. As Pavlovic and colleagues note, some health services – such as NHS England and Logan Hospital in Queensland, Australia – have restricted criteria for undergoing elective surgeries based on weight. Although weight-loss diets are generally safe and have potential benefits for individuals and health systems, the study casts doubt on the rationale for making these diets a requirement of elective surgery.

Commenting on the significance of the study, the journal’s editor, Professor Nick Finer, remarked: “This paper calls into question the policy of requiring weight loss before elective surgeries that has denied or delayed surgeries for people with overweight or obesity. The evidence for this is has always been weak and this study, in my mind, strengthens the argument against requiring pre-operative weight loss.”

The full paper, entitled “Effect of weight-loss diets prior to elective surgery on postoperative outcomes in obesity: a systematic review and meta-analysis”, is available to read now via Early View.