The Efficacy of Energy-Restricted Diets in Achieving Preoperative Weight Loss for Bariatric Patients: a Systematic Review


In bariatric practice, a preoperative weight loss of at least 5% is recommended. However, the hypocaloric diets prescribed vary and no consensus exists. This study examined the efficacy of preoperative diets in achieving 5% weight loss. From a systematic literature search, eight randomised controlled trials (n = 862) were identified. Half of the trials used a “very-low-calorie diet” whilst the rest employed a “low-calorie diet”. Only five diets achieved ≥ 5% weight loss over varying durations and energy intakes. By inference, compliance with a 700–1050 kcal (2929–4393 kJ) diet, consisting of moderate carbohydrate, high protein and low/moderate fat, for 3 weeks is likely to achieve 5% weight loss. A low-carbohydrate diet (< 20 g/day) may achieve this target within a shorter duration. Additional research is required to validate these conclusions.

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Correspondence to Orla Flannery.

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Naseer, F., Shabbir, A., Livingstone, B. et al. The Efficacy of Energy-Restricted Diets in Achieving Preoperative Weight Loss for Bariatric Patients: a Systematic Review. OBES SURG 28, 3678–3690 (2018).

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  • Obesity
  • Bariatric surgery
  • Metabolic surgery
  • Low-calorie diet
  • Very-low-calorie diet