Welcome tasmine. So excited for you - you will not regret it. I won't lie, a bypass is a challenge for sure but the rewards are awesome. You will be saying cheerio to food which has been your best friend and worst enemy. The aim of the game will be to shed your excess weight (prob within six to nine months depending on how much you have to lose - I lost nine stone in as many months) and by this time next year you will be eating 'normally' just very little of it, and avoiding fats and sugars which will make you very unwell indeed. You'll be fine. This forum is an amazing resource of advice and experience.
If your bypass is booked for mid Jan then I guess your Liver shrinking diet will be two weeks (mine was four). Your team will advise what the diet will be - mine was four cans of Weight Watchers soup, four Muller Light yogs and 500ml of semi-skimmed a day ONLY for the four weeks. It was the hardest thing I have done but I lost 12kg! The diet serves two purposes: the main one is to shrink the Liver so the surgeon can easily hook it out of the way and minimise risk of damage (you will have a small scar low between your breasts where the hook is inserted and attached to the side of the operating table), the second purpose is to mentally prepare you for not being able to eat like you have been doing ever again in your life. You must stick to this diet like glue - if you waver you are not ready for surgery and must be honest with your team who will defer the date so you can get in the zone. I cannot stress strongly enough how big the mental challenge of a bypass is ... But we do it, and you will too.
We will squidge up on the Losers' Bench for you hun. Exciting times! xxxx
PS: you can read about my journey in my thread in the part of the forum 'Gastric Bypass RNY: Inspirational photos before and after'. It is titled 'Feeling fit and fabulous ...'. It has had over 26.5k views and over 650 comments