Why do weight loss surgeons ask patients to lose weight before undergoing weight loss surgery?

Before having weight loss surgery one often hears that the surgical team insists on some degree of weight loss. Why do you insist on that? So it's not just weight loss per se. We ask patients to go on a special low calorie diet. This is about 800 kilocalories and most of the calories should really come from protein, fiber and liquids rather than carbohydrates and the The reason for this is twofold. One is, it helps to make the liver a little bit smaller, which reduces the risk of surgery itself, because most of the surgery is on the stomach, and this is underneath the liver. Second of all, it prepares you for the post-operative diet, which our dieticians will go through with you in detail. But for the first two weeks, this will be essentially liquids only, high protein intake, with the sort of caloric intake I just described. For the following few weeks, it will be pureed or blended food before moving on to soft diet and then normal diet, usually at around 8 weeks after surgery. So engaging with the dieticians and the diet before surgery is really important to get the best results to be able to cope with the post-operative diet as well.