English: Bariatric surgery is recognized as the most effective treatment modality for obesity. Since obesity levels are on the increase both locally and globally, it is expected that the number of procedures performed will increase in the future. A practical limitation to performing bariatric surgery is the fact that operating space within the abdomen is limited by excessive layers of abdominal fat and the presence of a large, fatty liver. Fat deposition in the liver is common in obesity. Reducing the fatty deposits in the liver can reduce the size of the liver, thereby in theory it can also reduce the complexity of the surgical technique. A number of individual trials have evaluated the potential of energy restriction for a period of two to 12 weeks before surgery to reduce the liver size and liver fat content. Data from these trials are promising, but individually does not provide sufficient evidence to justify evidence-based recommendation in favour of the use of restricted energy diets prior to surgery. This review combines the findings of individual trials in order to provide an evidence-base for such practice. At the time of protocol development, no systematic review has been published to document the benefits of energy restricted diets in reducing liver size and fat content in obese patients who are undergoing bariatric surgery for weight loss. A systematic literature search was undertaken to identify studies published between 1980 and 2012 on the research topic. Studies were evaluated and eliminated based on inclusion and exclusion criteria so that a total ofnine studies were included in the review. Study design and methodology were appraised, and results of individual trials compared and combined where appropriate in order to provide a comprehensive overview of current literature in the form of a narrative systematic review. A meta-analysis was not possible due to differences in reporting. Results indicated that preoperative diet restriction effectively reduces liver volume by decreasing the liver fat content. It was however not clear if these changes can be directly linked to reduction in operative complexity, reduction in intra-operative blood loss, or reduction in duration of surgery. Randomized, blinded trials are needed to confirm if a relationship exists. One well-designed study indicated reduction in post-operative complications. In conclusion, this review found that preoperative restricted energy diets used for an acute period before surgery can significantly reduce liver volume and fat content in obese patients, and may translate to improved patient outcome.
Afrikaans: Sleutelterme: vetsug, metaboliese sindroom, nie-alkoholiese lewer vervetting, bariatriese chirurgie, lae energie dieet, beperkte energie dieet, lewer volume, lewervet. Bariatriese chirurgie word beskou as die mees effektiewe manier om vetsug te behandel. Aangesien vetsug plaaslik en wêreldwyd aan die toeneem is, is die verwagting dat die hoeveelheid bariatriese chirurgie prosedures wat uitgevoer word, in die toekoms sal toeneem. ‘n Oormatige hoeveelheid buikvet tesame met ‘n vergrootte vet-geïnfiltreerde lewer beperk spasie in die buik van ‘n vetsugtige persoon, en skep ‘n praktiese probleem vir die chirurg wanneer bariatriese prosedure uitgevoer word. Die neerlegging van vet in lewer weefsel is algemeen in vetsugtige pasiënte. Deur vetneerleggings in die lewer te verminder kan die lewer se grootte verklein word, en teoreties kan dit dus help om die uitvoer van die prosedure te vergemaklik. Om vermindering van vetneerlegging in die lewer te bewerkstellig, het verskeie individuele navorsers ondersoek ingestel na die effek van beperkte energie diëte wat vir ‘n periode van twee tot 12 weke voor chirurgie deur die pasiënt gevolg word. Alhoewel hierdie studies belowende resultate gelewer het, regverdig dit nie die insluiting van ‘n riglyn oor die gebruik van ‘n lae energie dieet in sogenaamde navorsing-gebasseerde riglyne nie. Hierdie oorsig kombineer die bevindings van individuele navorsingstudies met die doel om bewys te lewer van die voordele verbonde aan hierdie gebruik. 133 Ten tyde die ontwikkeling van ‘n protokol vir hierdie studie, is geen sistematiese oorsig met betrekking tot die onderwerp gepubliseer nie. ‘n Sistematiese soektog na literatuur is gedoen om alle studies, gepubliseer tussen 1980 en 2012 en wat met die onderwerp verband hou, te identifiseer. Hierna is studies geëvalueer volgens insluitings- en uitsluitingskriteria, en verskeie studies is uitgesluit met slegs nege publikasies wat in die finale oorsig ingesluit is. Die ontwerp en metodes van hierdie publikasies is nagegaan, resultate is vergelyk en gekombineer waar van toepassing, ten einde ‘n omvattende oorsig te lewer van navorsing wat oor die onderwerp beskikbaar is. Weens verskille in data rapportering was dit nie moontlik om ‘n meta-analise uit te voer nie. Hierdie sistematiese oorsig het bevind dat energie beperking voor bariatriese chirurgie wel ‘n effektiewe manier is om vetinhoud van die lewer, en sodoende lewer grootte, te verminder. Dit is egter nie duidelik of hierdie veranderinge direk lei tot vermindering in chirurgiese kompleksiteit, verminderde bloedverlies tydens chirurgie, of ‘n korter tydsduur van chirurgie nie. Verdere inligting vanuit gerandomiseerde studies is nodig om ‘n moontlike verwantskap te bevestig. Een studie met ‘n goeie navorsingsontwerp het wel aangetoon dat post-operatiewe komplikasies verminder kan word. In samevatting het hierdie sistematiese oorsig bevind dat lewer volume en –vetinhoud beduidend verminder kan word deur ‘n beperkte energie dieet vir ‘n kort tydperk voor chirurgie te volg, en dat dit ook moontlik pasiënt-uitkoms kan verbeter.