Patient who come for pancreatic surgery and vein resection/reconstruction will be randomized before surgery in two groups. Intervention group will start the no-fat diet right after surgery, with MCT-oil supplement. Diet will be continued up to 14 days after surgery. The control group will start the diet if chyle leak is diagnosed. Criteria of chyle leak in this study is appearance of milky-coloured fluid from the surgical drains in post-operative day 3 and drain fluids triglyceride levels must be high (\>1,5 mmol/l). After enough patients have been recruited in the study, patient records are then analyzed to see if the no-fat diet has any effect on incidence of chyle-leak.
